Changes in carbohydrate concentration and amylolytic activity in germinating maize
- Authors: Breen, C M
- Date: 1969
- Subjects: Corn -- Research Corn -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4251 , http://hdl.handle.net/10962/d1007680
- Description: Changes in the concentration of some carbohydrates and in amylolytic activity have been followed during germination of Zea. Mays L. var. Hickory King and var. Early Pearl. Assay techniques have been developed which permitted assay of individual grains. Thus during the investigation both groups and individual grains were used as samples. The use of groups permitted control of assay technique. Length of radicle, coleoptile and lateral roots were recorded in order to permit quantitative estimation of correlation between growth and the concentration of the various carbohydrates. Initially, during the study of changes in the carbohydrate concentration in Hickory King grains, total reducing sugar, sucrose and dextrin concentrations were estimated. However, the results obtained for changes in dextrin concentration, although reproduceable, thereby indicating reliable assay technique, presented a confusing picture and, in view of the apparent importance of sucrose and reducing sugar concentration, assay of dextrin concentration was discontinued in a subsequent study of Early Pearl. Instead changes in total reducing sugar, sucrose and glucose concentrations were followed. The results revealed that there is very considerable variability in physiological activity between grains subjected to the same germination conditions. However, all, irrespective of variety, follow the same basic metabolic pattern during germination. The trends observed were: (i) Reducing sugar accumulates slowly during the first 72-96 hours germination, but thereafter accumulation is very rapid, although concentration may decrease towards the end of the gestation period. (ii) Glucose follows a similar pattern to reducing sugar, accumulating slowly during the early stages of germination, followed by a period of rapid increase in concentration, which may decrease towards the end of the germination period. (iii) Sucrose concentration in dormant grains is fairly high, but it decreases markedly during the first 96 hours germination. This is followed by a phase of sucrose accumulation. (iv) Dextrin concentration shows two peaks. Initial level is low, but it accumulates rapidly during the first 72 hours. The level decreases between 72 and 120 hours but increases when the germination period is increased to 192 hours, after which there is a marked decrease. It was impossible, from the data relating to the study of individual grains, to discern a trend in dextrin concentration. With the exception of dextrin, about which there is little information, the results are in general agreement with the literature. Investigation of correlation between the various carbohydrates and between these and growth revealed that: (i) reducing sugar concentration and growth are positively correlated ; (ii) glucose concentration and growth are positively correlated; (iii) sucrose and reducing sugar concentrctions are negatively correlated during the initial stages of germination; (iv) sucrose and glucose concentrations are negatively correlated during early germination; (v) glucose and reducing sugar are positively correlated; (vi) in general, correlation between growth and concentration of the carbohydrates studied, decreases during the later periods of germination. These observations suggested that growth was, at least during the early stages of germination, dependent on the level of reducing sugar, and more particularly on the level of glucose, and that sucrose is the principal source of reducing sugar during this period. The relationship between amylase activity (total alpha- and beta-amylase activity) and reducing sugar concentration tends to be curvilinear, which suggests that amylolytic activity produces relatively little reducing sugar during early gennination, even though amylase activity and growth may be positively correlated. The results suggest, contrary to the observations of previous workers, that alpha-amylolytic activity may be present in dormant grains and that maize is not characterised by low levels of beta-amylase activity during germination. From the observations it is concluded that the initinl accumulati on of reducing sugar is the result of sucrose hydrolysis, and therefore sucrose is an importnnt metabolite durjng early germination. Amylolytic activity contributes little reducing sugar durlng the initia1 stages of germinatIon but that after approximately 72 hours it represents the major source of reducing sugar.
- Full Text:
- Date Issued: 1969
- Authors: Breen, C M
- Date: 1969
- Subjects: Corn -- Research Corn -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4251 , http://hdl.handle.net/10962/d1007680
- Description: Changes in the concentration of some carbohydrates and in amylolytic activity have been followed during germination of Zea. Mays L. var. Hickory King and var. Early Pearl. Assay techniques have been developed which permitted assay of individual grains. Thus during the investigation both groups and individual grains were used as samples. The use of groups permitted control of assay technique. Length of radicle, coleoptile and lateral roots were recorded in order to permit quantitative estimation of correlation between growth and the concentration of the various carbohydrates. Initially, during the study of changes in the carbohydrate concentration in Hickory King grains, total reducing sugar, sucrose and dextrin concentrations were estimated. However, the results obtained for changes in dextrin concentration, although reproduceable, thereby indicating reliable assay technique, presented a confusing picture and, in view of the apparent importance of sucrose and reducing sugar concentration, assay of dextrin concentration was discontinued in a subsequent study of Early Pearl. Instead changes in total reducing sugar, sucrose and glucose concentrations were followed. The results revealed that there is very considerable variability in physiological activity between grains subjected to the same germination conditions. However, all, irrespective of variety, follow the same basic metabolic pattern during germination. The trends observed were: (i) Reducing sugar accumulates slowly during the first 72-96 hours germination, but thereafter accumulation is very rapid, although concentration may decrease towards the end of the gestation period. (ii) Glucose follows a similar pattern to reducing sugar, accumulating slowly during the early stages of germination, followed by a period of rapid increase in concentration, which may decrease towards the end of the germination period. (iii) Sucrose concentration in dormant grains is fairly high, but it decreases markedly during the first 96 hours germination. This is followed by a phase of sucrose accumulation. (iv) Dextrin concentration shows two peaks. Initial level is low, but it accumulates rapidly during the first 72 hours. The level decreases between 72 and 120 hours but increases when the germination period is increased to 192 hours, after which there is a marked decrease. It was impossible, from the data relating to the study of individual grains, to discern a trend in dextrin concentration. With the exception of dextrin, about which there is little information, the results are in general agreement with the literature. Investigation of correlation between the various carbohydrates and between these and growth revealed that: (i) reducing sugar concentration and growth are positively correlated ; (ii) glucose concentration and growth are positively correlated; (iii) sucrose and reducing sugar concentrctions are negatively correlated during the initial stages of germination; (iv) sucrose and glucose concentrations are negatively correlated during early germination; (v) glucose and reducing sugar are positively correlated; (vi) in general, correlation between growth and concentration of the carbohydrates studied, decreases during the later periods of germination. These observations suggested that growth was, at least during the early stages of germination, dependent on the level of reducing sugar, and more particularly on the level of glucose, and that sucrose is the principal source of reducing sugar during this period. The relationship between amylase activity (total alpha- and beta-amylase activity) and reducing sugar concentration tends to be curvilinear, which suggests that amylolytic activity produces relatively little reducing sugar during early gennination, even though amylase activity and growth may be positively correlated. The results suggest, contrary to the observations of previous workers, that alpha-amylolytic activity may be present in dormant grains and that maize is not characterised by low levels of beta-amylase activity during germination. From the observations it is concluded that the initinl accumulati on of reducing sugar is the result of sucrose hydrolysis, and therefore sucrose is an importnnt metabolite durjng early germination. Amylolytic activity contributes little reducing sugar durlng the initia1 stages of germinatIon but that after approximately 72 hours it represents the major source of reducing sugar.
- Full Text:
- Date Issued: 1969
Family planning in the White population of Port Elizabeth
- Authors: Higgins, Edward
- Date: 1969
- Subjects: Birth control -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3368 , http://hdl.handle.net/10962/d1012267
- Description: This study of family planning is based on a sample survey of 900 married white women under 50 years of age resident at the time of the survey (June 20th - August 31st, 1964) in the municipalities of Port Elizabeth and Walmer. The present chapter outlines briefly the setting, aims and scope of the study. In South Africa very little has been attempted in the line of the study of human reproductive behaviour, fertility control and the associated norms and values. Indeed, in South Africa there are serious gaps in our demographic knowledge and until fairly recently (1960) even the official census left much to be desired. It is hoped that the data gathered in this study will fill some of the gaps in our demographic knowledge about one particular urban area of South Africa as far as its white population is concerned. The present study is the first of its kind to be conducted in Port Elizabeth although a somewhat similar study was conducted in Johannesburg during 1957-58. As far as Port Elizabeth is concerned, this study breaks new ground, demographically speaking. Chapter 1, p. 1.
- Full Text:
- Date Issued: 1969
- Authors: Higgins, Edward
- Date: 1969
- Subjects: Birth control -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3368 , http://hdl.handle.net/10962/d1012267
- Description: This study of family planning is based on a sample survey of 900 married white women under 50 years of age resident at the time of the survey (June 20th - August 31st, 1964) in the municipalities of Port Elizabeth and Walmer. The present chapter outlines briefly the setting, aims and scope of the study. In South Africa very little has been attempted in the line of the study of human reproductive behaviour, fertility control and the associated norms and values. Indeed, in South Africa there are serious gaps in our demographic knowledge and until fairly recently (1960) even the official census left much to be desired. It is hoped that the data gathered in this study will fill some of the gaps in our demographic knowledge about one particular urban area of South Africa as far as its white population is concerned. The present study is the first of its kind to be conducted in Port Elizabeth although a somewhat similar study was conducted in Johannesburg during 1957-58. As far as Port Elizabeth is concerned, this study breaks new ground, demographically speaking. Chapter 1, p. 1.
- Full Text:
- Date Issued: 1969
Some aspects of the ecology of the citrus red mite, Panonychus citri (McGregor), in the Eastern Cape Province
- Authors: Keetch, D P
- Date: 1969
- Subjects: Citrus -- Diseases and pests -- South Africa -- Eastern Cape Plant mites -- Ecology -- South Africa Citrus red mite Citrus red mite -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5860 , http://hdl.handle.net/10962/d1012630
- Description: The citrus red mite, Panonychus citri (McGregor), is a relatively new pest to South African citriculture, the first recorded injury to citrus trees was from Rustenberg, Transvaal in 1950 (Smith 1953). In the U.S.A. the biology of this mite has been studied by Quayle (1938), Prendergast (1938), English and Turnipseed (1941), DeBach (1947), DeBach et al. (1950), Ebeling (1959) and Jeppson et al. (1957,1961). However, in South Africa little information is available concerning the ecolopy of the citrus red mite. The majority of the literature pertaining to P. citri in Republic, (Smith (1953), Mentz (1954), Stofberg (1959), Schwartz (1965) and Brodrick (1965) is of a descriptive nature, and mainly concerned with the chemical control of the mite. The only biological investigation on the development of P.citri, and the effect of insecticides and insect predators on its biology, under South African conditions, was made by van Rooyen (1966) at Zebediela, Transvaal. In the control of citrus pests, such as the citrus red mite, that need for a better understanding of their ecology has been well emphasised by DeBach (1951) and Griffiths (1951). DeBach (1951) in particular, stressed the danger of the continued reliance on insecticidal treatment as the only method of nest control, and has pointed out that persistent chemical applications may only serve to intensify the pest problem. He has suggested that a closer study of the environment of the pest species could provide a solution to the problems now encountered as a result of insecticidal control measures. Intro., p. 1-2.
- Full Text:
- Date Issued: 1969
- Authors: Keetch, D P
- Date: 1969
- Subjects: Citrus -- Diseases and pests -- South Africa -- Eastern Cape Plant mites -- Ecology -- South Africa Citrus red mite Citrus red mite -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5860 , http://hdl.handle.net/10962/d1012630
- Description: The citrus red mite, Panonychus citri (McGregor), is a relatively new pest to South African citriculture, the first recorded injury to citrus trees was from Rustenberg, Transvaal in 1950 (Smith 1953). In the U.S.A. the biology of this mite has been studied by Quayle (1938), Prendergast (1938), English and Turnipseed (1941), DeBach (1947), DeBach et al. (1950), Ebeling (1959) and Jeppson et al. (1957,1961). However, in South Africa little information is available concerning the ecolopy of the citrus red mite. The majority of the literature pertaining to P. citri in Republic, (Smith (1953), Mentz (1954), Stofberg (1959), Schwartz (1965) and Brodrick (1965) is of a descriptive nature, and mainly concerned with the chemical control of the mite. The only biological investigation on the development of P.citri, and the effect of insecticides and insect predators on its biology, under South African conditions, was made by van Rooyen (1966) at Zebediela, Transvaal. In the control of citrus pests, such as the citrus red mite, that need for a better understanding of their ecology has been well emphasised by DeBach (1951) and Griffiths (1951). DeBach (1951) in particular, stressed the danger of the continued reliance on insecticidal treatment as the only method of nest control, and has pointed out that persistent chemical applications may only serve to intensify the pest problem. He has suggested that a closer study of the environment of the pest species could provide a solution to the problems now encountered as a result of insecticidal control measures. Intro., p. 1-2.
- Full Text:
- Date Issued: 1969
The growth of flue-cured tobacco in acid soils
- Authors: Ryding, William Wallace
- Date: 1969
- Subjects: Flue-cured tobacco -- Zimbabwe , Acid soils -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4495 , http://hdl.handle.net/10962/d1013110
- Description: The main effects of lime, aluminium, iron and manganese were studied in field and greenhouse grown tobacco; relations between soil and plant measurements were examined. Ground limestone, ground mixed lime, ground dolomite and slaked lime at rates equivalent to 1,000 and 2,000 lb. CaC0₃/acre increased yield and quality of flue-cured tobacco both on Triassic and granite sands, whether applied early (February/March) or late (September); the highest rate and late application were often best. Yields increased with 4,000 and 6,000 lb. dolomite/acre applied late, but quality decreased when the pH was about 6.0. Lime did not affect leaf maturity as reflected by nitrogen and reducing sugars concentration . Where leaf discolouration (slate) occurred, the best quality and least discoloured leaf had the lowest manganese concentration and was grown on limed soil. On a very acid and probably nitrogen deficient soil, lime, borax and nitrogen (nitrate only tested) reduced the discolouration and improved the quality, but potassium sulphate increased discolouration and decreased quality. Calcium concentration in the leaf was increased by lime, particularly calcitic materials, and magnesium concentration was increased by dolomite. Lime also increased the filling value and petroleum ether extract, but decreased manganese, boron, chloride and sometimes potassium, and had no effect on phosphorus, nitrogen, aluminium, iron, crude fibre, nicotine, reducing sugars and equilibrium moisture. The inorganic composition of greenhouse plants was similar; generally gypsum increased calcium concentration more than calcium carbonate but it did not affect manganese concentration, which was decreased by calcium carbonate. In the stem and roots of field grown plants (dolomite only tested), the concentration of magnesium was increased but the concentrations of calcium, potassium, aluminium and iron were unaffected. Although the concentration of nitrogen was increased and that of phosphorus was decreased in the stem, these were unaffected in the roots. Aluminium and iron behaved differently to other nutrient ions, being more concentrated in the roots than aerial plant parts. Boron and magnesium deficiencies were observed in a dry and wet year, respectively, suggesting that variable mineral deficiencies can affect responses to lime. Initially soil pH was affected more by source of lime, but later mostly by rates. Slaked lime increased the soil pH more than did ground limestone, mixed lime or dolomite. In a glasshouse experiment, pH was more important than calcium supply and in the field, the largest yields were often associated with the highest pH. In pot experiments, aluminium drastically reduced yields in nutrient solution but not in soils, whereas iron was more severe in soils; manganese had little effect on yield. Manganese was readily taken up and translocated to the tops, but aluminium and iron were mainly concentrated in the roots, as was found in field grown plants. Iron decreased manganese concentration in all plant parts and aluminium decreased calcium and manganese in nutrient solution only. Although aluminium and iron generally increased the concentration of phosphorus in the roots, they did not interfere with phosphorus transport in the plant. Manganese caused the leaf to become chlorotic and when no iron was present the upper leaves became yellow, and developed brown and white lesions. However, in soil grown plants, sufficient iron was present in the soil solution to prevent break down of tissue. Yellowing of the upper leaves also occurred when plants were grown in nutrient solution with aluminium and no iron; when both were present, the plants were darker in colour. Although aluminium damaged roots in nutrient solution, high rates of iron severely damaged leaves of plants grown in soil. Since the concentrations of aluminium, iron and manganese were decreased in the soil solution by liming, they were compared with plant growth and composition in 17 different soils, with and without lime. As was expected, lime increased soil pH. It also increased exchangeable calcium, but decreased exchangeable aluminium, iron and manganese; exchangeable magnesium and potassium and resin extractable phosphorus were not affected. As the Ratio Law does not hold for all Rhodesian soils, anion adsorption will be avoided if the soils are equilibrated with O.OOOSM CaC1₂; the concentrations of the cations in solution were affected in the same way as exchangeable cations, but phosphorus was increased. There was no relationship between yield of tobacco and its chemical composition. The correlations between soil solution data and plant composition were poor, except for manganese and phosphorus; the relation between Mn ppm. in plant vsa (superscript)Mn/a (superscript)Ca + Mg (enclosed in square root sign √) in solution, and P% vs pH₂ P0₄ or pH₂ P0₄ +½ pCa, were both curvilinear. On the other hand, all measurements of exchangeable cations were poorly correlated with plant composition. Finally yield was poorly correlated with soil solution data, and pH was as satisfactory as any other measurement tested. Manganese toxicity was observed on three soils, and a probable manganese deficiency on one. It was not possible to define a limit above which manganese toxicity occurred, but manganese deficiency developed at about 63 ppm. manganese. Variations in pH and the availability of aluminium, iron and manganese occurred when soils were incubated at about field capacity, generally the main effects having developed within seven days. In all soils, there was an initial increase in soil pH and a maximum value was reached in one to four days, decreasing by variable amounts with longer periods of incubation. Although the concentration of aluminium was larger than that of iron, the relation between both ions and soil pH was curvilinear, their concentrations increasing with decreasing pH. Increased temperature of incubation increased pH with a resultant decrease in the concentration of aluminium, but in one soil it appreciably increased the availability of iron in the early periods of incubation. Autumn and spring ploughing did not affect subsequent pH or the concentration of aluminium and iron in the soil solution. Manganese concentration varied from soil to soil and was not related to soil pH. In most soils there was a decrease in manganese concentration with length of incubation and it decreased more rapidly the lower the initial concentration. Temperature effects were variable and moisture affected the behaviour of manganese more than temperature. These findings and the distribution of aluminium, iron and manganese in the plant helped to explain the poor correlations.
- Full Text:
- Date Issued: 1969
- Authors: Ryding, William Wallace
- Date: 1969
- Subjects: Flue-cured tobacco -- Zimbabwe , Acid soils -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4495 , http://hdl.handle.net/10962/d1013110
- Description: The main effects of lime, aluminium, iron and manganese were studied in field and greenhouse grown tobacco; relations between soil and plant measurements were examined. Ground limestone, ground mixed lime, ground dolomite and slaked lime at rates equivalent to 1,000 and 2,000 lb. CaC0₃/acre increased yield and quality of flue-cured tobacco both on Triassic and granite sands, whether applied early (February/March) or late (September); the highest rate and late application were often best. Yields increased with 4,000 and 6,000 lb. dolomite/acre applied late, but quality decreased when the pH was about 6.0. Lime did not affect leaf maturity as reflected by nitrogen and reducing sugars concentration . Where leaf discolouration (slate) occurred, the best quality and least discoloured leaf had the lowest manganese concentration and was grown on limed soil. On a very acid and probably nitrogen deficient soil, lime, borax and nitrogen (nitrate only tested) reduced the discolouration and improved the quality, but potassium sulphate increased discolouration and decreased quality. Calcium concentration in the leaf was increased by lime, particularly calcitic materials, and magnesium concentration was increased by dolomite. Lime also increased the filling value and petroleum ether extract, but decreased manganese, boron, chloride and sometimes potassium, and had no effect on phosphorus, nitrogen, aluminium, iron, crude fibre, nicotine, reducing sugars and equilibrium moisture. The inorganic composition of greenhouse plants was similar; generally gypsum increased calcium concentration more than calcium carbonate but it did not affect manganese concentration, which was decreased by calcium carbonate. In the stem and roots of field grown plants (dolomite only tested), the concentration of magnesium was increased but the concentrations of calcium, potassium, aluminium and iron were unaffected. Although the concentration of nitrogen was increased and that of phosphorus was decreased in the stem, these were unaffected in the roots. Aluminium and iron behaved differently to other nutrient ions, being more concentrated in the roots than aerial plant parts. Boron and magnesium deficiencies were observed in a dry and wet year, respectively, suggesting that variable mineral deficiencies can affect responses to lime. Initially soil pH was affected more by source of lime, but later mostly by rates. Slaked lime increased the soil pH more than did ground limestone, mixed lime or dolomite. In a glasshouse experiment, pH was more important than calcium supply and in the field, the largest yields were often associated with the highest pH. In pot experiments, aluminium drastically reduced yields in nutrient solution but not in soils, whereas iron was more severe in soils; manganese had little effect on yield. Manganese was readily taken up and translocated to the tops, but aluminium and iron were mainly concentrated in the roots, as was found in field grown plants. Iron decreased manganese concentration in all plant parts and aluminium decreased calcium and manganese in nutrient solution only. Although aluminium and iron generally increased the concentration of phosphorus in the roots, they did not interfere with phosphorus transport in the plant. Manganese caused the leaf to become chlorotic and when no iron was present the upper leaves became yellow, and developed brown and white lesions. However, in soil grown plants, sufficient iron was present in the soil solution to prevent break down of tissue. Yellowing of the upper leaves also occurred when plants were grown in nutrient solution with aluminium and no iron; when both were present, the plants were darker in colour. Although aluminium damaged roots in nutrient solution, high rates of iron severely damaged leaves of plants grown in soil. Since the concentrations of aluminium, iron and manganese were decreased in the soil solution by liming, they were compared with plant growth and composition in 17 different soils, with and without lime. As was expected, lime increased soil pH. It also increased exchangeable calcium, but decreased exchangeable aluminium, iron and manganese; exchangeable magnesium and potassium and resin extractable phosphorus were not affected. As the Ratio Law does not hold for all Rhodesian soils, anion adsorption will be avoided if the soils are equilibrated with O.OOOSM CaC1₂; the concentrations of the cations in solution were affected in the same way as exchangeable cations, but phosphorus was increased. There was no relationship between yield of tobacco and its chemical composition. The correlations between soil solution data and plant composition were poor, except for manganese and phosphorus; the relation between Mn ppm. in plant vsa (superscript)Mn/a (superscript)Ca + Mg (enclosed in square root sign √) in solution, and P% vs pH₂ P0₄ or pH₂ P0₄ +½ pCa, were both curvilinear. On the other hand, all measurements of exchangeable cations were poorly correlated with plant composition. Finally yield was poorly correlated with soil solution data, and pH was as satisfactory as any other measurement tested. Manganese toxicity was observed on three soils, and a probable manganese deficiency on one. It was not possible to define a limit above which manganese toxicity occurred, but manganese deficiency developed at about 63 ppm. manganese. Variations in pH and the availability of aluminium, iron and manganese occurred when soils were incubated at about field capacity, generally the main effects having developed within seven days. In all soils, there was an initial increase in soil pH and a maximum value was reached in one to four days, decreasing by variable amounts with longer periods of incubation. Although the concentration of aluminium was larger than that of iron, the relation between both ions and soil pH was curvilinear, their concentrations increasing with decreasing pH. Increased temperature of incubation increased pH with a resultant decrease in the concentration of aluminium, but in one soil it appreciably increased the availability of iron in the early periods of incubation. Autumn and spring ploughing did not affect subsequent pH or the concentration of aluminium and iron in the soil solution. Manganese concentration varied from soil to soil and was not related to soil pH. In most soils there was a decrease in manganese concentration with length of incubation and it decreased more rapidly the lower the initial concentration. Temperature effects were variable and moisture affected the behaviour of manganese more than temperature. These findings and the distribution of aluminium, iron and manganese in the plant helped to explain the poor correlations.
- Full Text:
- Date Issued: 1969
The production and marketing of South African Maize since 1910, with special reference to the years 1954 to 1966
- Authors: Brits, Rudolph Nieuwoudt
- Date: 1969
- Subjects: South Africa. Maize Board , Corn industry -- South Africa , Corn -- South Africa -- Marketing , Corn -- South Africa -- Marketing -- Government policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1104 , http://hdl.handle.net/10962/d1013386
- Description: From Introduction: There is no evidence available that maize was known in the old world in ancient times. Seeds of barley and wheat have been found in ancient near eastern sites, but never has there been any trace of maize at all. Furthermore, maize as a plant is not mentioned in the Bible, and neither Greek nor Chinese literature makes any reference to maize. There is, therefore, nothing that suggests that maize was known in the Old world before about 1492. However, at that time, Christopher Columbus returned with a report about a new grain called "Maiz". At a later date explorers visiting America found that maize was being grown and consumed by the Red Indians in places as far apart as Canada and Chile. The consensus of opinion is, therefore, that maize originated in America and was only subsequently imported into Europe. However, in a very excellent paper, Dr. M.D.W. Jeffreys comes to the very convincing conclusion that "Maize, a non-self-propagating American plant, was introduced to east African littorals before the Portuguese rounded the Cape and was seen by the Chinese navigators at Melinde Circa 1414… Maize was brought to the Indian Ocean littorals by Arabs before 1400. Maize was brought into southern Africa by the Nguni by 1400 and later by the baVenda. Maize was introduced by the Dutch in 1658. There is no evidence that maize was introduced by the Portuguese. Irrespective of the exact date when maize was introduced into South Africa, it was only from the year 1840 that there was any real agricultural development in South Africa. At this date, all those who had participated in the Great Trek had more or less settled down, and substantial areas were planted with wheat, maize and oats.
- Full Text:
- Date Issued: 1969
- Authors: Brits, Rudolph Nieuwoudt
- Date: 1969
- Subjects: South Africa. Maize Board , Corn industry -- South Africa , Corn -- South Africa -- Marketing , Corn -- South Africa -- Marketing -- Government policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1104 , http://hdl.handle.net/10962/d1013386
- Description: From Introduction: There is no evidence available that maize was known in the old world in ancient times. Seeds of barley and wheat have been found in ancient near eastern sites, but never has there been any trace of maize at all. Furthermore, maize as a plant is not mentioned in the Bible, and neither Greek nor Chinese literature makes any reference to maize. There is, therefore, nothing that suggests that maize was known in the Old world before about 1492. However, at that time, Christopher Columbus returned with a report about a new grain called "Maiz". At a later date explorers visiting America found that maize was being grown and consumed by the Red Indians in places as far apart as Canada and Chile. The consensus of opinion is, therefore, that maize originated in America and was only subsequently imported into Europe. However, in a very excellent paper, Dr. M.D.W. Jeffreys comes to the very convincing conclusion that "Maize, a non-self-propagating American plant, was introduced to east African littorals before the Portuguese rounded the Cape and was seen by the Chinese navigators at Melinde Circa 1414… Maize was brought to the Indian Ocean littorals by Arabs before 1400. Maize was brought into southern Africa by the Nguni by 1400 and later by the baVenda. Maize was introduced by the Dutch in 1658. There is no evidence that maize was introduced by the Portuguese. Irrespective of the exact date when maize was introduced into South Africa, it was only from the year 1840 that there was any real agricultural development in South Africa. At this date, all those who had participated in the Great Trek had more or less settled down, and substantial areas were planted with wheat, maize and oats.
- Full Text:
- Date Issued: 1969
The theory and practice of "Klangreihenkomposition"
- Authors: Nowotny, Norbert W
- Date: 1969
- Subjects: Hauer, Josef Matthias, 1883-1959 , Music theory , Twelve-tone system , Musical intervals and scales , Tonality
- Language: German
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2693 , http://hdl.handle.net/10962/d1013394
- Description: Diese Arbeit befaßt sich mit der "Klangreihenlehre'', einer Musiktheorie, die von Josef Matthias Hauer aufgestellt und von meinem Lehrer Othmar Steinbauer weiterentwickelt wurde. Diese auf der Gesetzmäßigkeit der zwölf Töne beruhende Satzlehre hat jedoch mit der "Reihentechnik" jener Musik, die schlechthin als "Zwölftonmusik" bezeichnet wird, nichts gemein. Obwohl eine beachtliche Literatur über J.M. Hauer vorliegt, ist sie doch, was Hauers Musiktheorie betrifft, nicht zufriedenstellend, da sie hauptsächlich auf sein Leben und seine Musikphilosophie eingeht.
- Full Text:
- Date Issued: 1969
- Authors: Nowotny, Norbert W
- Date: 1969
- Subjects: Hauer, Josef Matthias, 1883-1959 , Music theory , Twelve-tone system , Musical intervals and scales , Tonality
- Language: German
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2693 , http://hdl.handle.net/10962/d1013394
- Description: Diese Arbeit befaßt sich mit der "Klangreihenlehre'', einer Musiktheorie, die von Josef Matthias Hauer aufgestellt und von meinem Lehrer Othmar Steinbauer weiterentwickelt wurde. Diese auf der Gesetzmäßigkeit der zwölf Töne beruhende Satzlehre hat jedoch mit der "Reihentechnik" jener Musik, die schlechthin als "Zwölftonmusik" bezeichnet wird, nichts gemein. Obwohl eine beachtliche Literatur über J.M. Hauer vorliegt, ist sie doch, was Hauers Musiktheorie betrifft, nicht zufriedenstellend, da sie hauptsächlich auf sein Leben und seine Musikphilosophie eingeht.
- Full Text:
- Date Issued: 1969
Theoretical aspects of the reaction of zirconium compunds and vegetable tannins with the chromium-collagen complex
- Williams-Wynn, David Ernest Arthur
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1969
- Subjects: Zirconium compounds , Collagen , Chromium compounds , Tannins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4512 , http://hdl.handle.net/10962/d1013455
- Description: Studies have been made of the reactions which take place when zirconium compounds and vegetable tannins react with chromium tanned leather, in order to elucidate the mechanisms of the reactions which occur on retannage. Statistical procedures have been used in all investigations because of the variable nature of the substrate, and computer techniques have been applied to the repetitive statistical computations. Although chromium and vegetable tannages are well understood, further information on the reaction of zirconium with collagen was necessary before attempting to interpret the results of the studies of combination tannages with chromium, and this has been obtained by a comparative study of the reactions of chromium and zirconium with modified collagen. It is concluded that the mechanism of the reaction of basic zirconium sulphate with collagen is multipoint attachment of the tanning material by residual valency forces, although charge effects with basic groups may be supplementary. Zirconyl chloride reacts with carboxyl groups but does not form satisfactory, stable cross-links with collagen. Further evidence for this theory was obtained from the investigation of the reaction of zirconium compounds with chromium tanned collagen. Zirconyl sulphate does not interfere with effective chromium tannage and therefore can have little affinity for the carboxyl groups on the protein, but it displaces chromium complexes loosely held by auxiliary valencies without reducing the shrinkage temperature of the chromium leather Zirconyl chloride, although only fixed to a limited extent, apparently forms co-ordination compounds with the carboxyl groups, disrupting the chromium tannage because there is an over-all loss of hydrothermal stability. There is no evidence that zirconium co-ordinates with, or releases acid from chromium-collagen complexes, since combination chromium/zirconium tanned leathers are stable on storage. Retannage of chromium tanned leather with vegetable tanning materials generally results in loss of strength and a product which tends to deteriorate on ageing. Lower initial strength is probably due to the increased avidity of chromium tanned pelt for vegetable tannins, resulting from the liberation of internally neutralised reactive sites which are not normally available in vegetable tannage, and from the co- ordination of vegetable tannins and non-tannins to the chromium complex with the displacement of sulphate radicals. From a study of the retannage of chromium tanned modified collagen, it appears that basic groups probably play an important part in the rapid absorption of vegetable tannin. These reactions result in overloading of the fibre and an increased number of cross-links, both of which tend to produce weak leather. Deterioration with age is primarily a hydrolytic degradation of the protein which is catalysed by acid liberated from the chromium complexes by the entry of vegetable tannins, those factors which favour the formation of acid causing greater and more rapid deterioration.
- Full Text:
- Date Issued: 1969
- Authors: Williams-Wynn, David Ernest Arthur
- Date: 1969
- Subjects: Zirconium compounds , Collagen , Chromium compounds , Tannins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4512 , http://hdl.handle.net/10962/d1013455
- Description: Studies have been made of the reactions which take place when zirconium compounds and vegetable tannins react with chromium tanned leather, in order to elucidate the mechanisms of the reactions which occur on retannage. Statistical procedures have been used in all investigations because of the variable nature of the substrate, and computer techniques have been applied to the repetitive statistical computations. Although chromium and vegetable tannages are well understood, further information on the reaction of zirconium with collagen was necessary before attempting to interpret the results of the studies of combination tannages with chromium, and this has been obtained by a comparative study of the reactions of chromium and zirconium with modified collagen. It is concluded that the mechanism of the reaction of basic zirconium sulphate with collagen is multipoint attachment of the tanning material by residual valency forces, although charge effects with basic groups may be supplementary. Zirconyl chloride reacts with carboxyl groups but does not form satisfactory, stable cross-links with collagen. Further evidence for this theory was obtained from the investigation of the reaction of zirconium compounds with chromium tanned collagen. Zirconyl sulphate does not interfere with effective chromium tannage and therefore can have little affinity for the carboxyl groups on the protein, but it displaces chromium complexes loosely held by auxiliary valencies without reducing the shrinkage temperature of the chromium leather Zirconyl chloride, although only fixed to a limited extent, apparently forms co-ordination compounds with the carboxyl groups, disrupting the chromium tannage because there is an over-all loss of hydrothermal stability. There is no evidence that zirconium co-ordinates with, or releases acid from chromium-collagen complexes, since combination chromium/zirconium tanned leathers are stable on storage. Retannage of chromium tanned leather with vegetable tanning materials generally results in loss of strength and a product which tends to deteriorate on ageing. Lower initial strength is probably due to the increased avidity of chromium tanned pelt for vegetable tannins, resulting from the liberation of internally neutralised reactive sites which are not normally available in vegetable tannage, and from the co- ordination of vegetable tannins and non-tannins to the chromium complex with the displacement of sulphate radicals. From a study of the retannage of chromium tanned modified collagen, it appears that basic groups probably play an important part in the rapid absorption of vegetable tannin. These reactions result in overloading of the fibre and an increased number of cross-links, both of which tend to produce weak leather. Deterioration with age is primarily a hydrolytic degradation of the protein which is catalysed by acid liberated from the chromium complexes by the entry of vegetable tannins, those factors which favour the formation of acid causing greater and more rapid deterioration.
- Full Text:
- Date Issued: 1969
A structural investigation of the sulphated polysaccharides of Aeodes orbitosa and Phyllymenia cornea
- Authors: Parolis, Haralambos
- Date: 1968
- Subjects: Polysaccharides , Marine algae -- Composition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4487 , http://hdl.handle.net/10962/d1012999
- Description: A highly sulphated, methylated polysaccharide, aeodan, isolated from the red seaweed Aeodes orbitosa was shown to contain galactose, 2-̲̲O-methyl-D-galactose, 4-O̲-methyl-Lgalactose, 6-O̲-methyl-D-galactose, xylose, and glycerol. The polysaccharide was desulphated with methanolic hydrogen chloride. Periodate oxidation of aeodan and desulphated aeodan, followed by reduction and hydrolysis, revealed the presence of 1,4- and 1,3-linked galactose residues and 1,3-linked 6-O̲-methy l-D-galactose residues in aeodan. Treatment of aeodan with sodium hydroxide revealed that the majority of the ester sulphate groups were alkali stable. Methylation of desulphated aeodan revealed that the polysaccharide was composed entirely of 1,3 and 1,4 links. Methylation of aeodan revealed the presence of 1,3- and 1,4- linked units, 1,3-linked galactose-2-sulphate, and 1,3-linked galactose-2, 6-disulphate units in the polysaccharide. Partial hydrolysis of aeodan resulted in the isolation and characterisation of 3-O̲-D-galactopyranosyl-D-galactose and 4-O̲-ß-D-galactopyranosyl- D-galactose. A sulphated, methylated polysaccharide, phyllymenan, isolated from the red seaweed Phyllymenia cornea was shown to contain galactose, 2-O̲-methyl-D-galactose, 4-O̲-methyl L- galactose , 6-O̲-methyl -D-galactose, and xylose. The polysaccharide was completely desulphated with methanolic hydrogen chloride. Periodate oxidation of phyllymenan before and after desulphation revealed that removal of the sulphate ester groups had not produced any new adjacent hydroxyl groups. Alkali treatment of phyllymenan revealed that the ester sulphate groups were alkali stable. Methylation studies on phyllymenan revealed the presence of 1,3- and 1,4-linked units, 1,3-linked galactose-2-sulphate, and 1,3-linked galactose- 2,6-disulphate units in the polysaccharide. Partial hydrolysis of phyllymenan revealed the presence or 4-O-̲ß- D-Dgalactopyranosyl- D-galactosc, 4-O-̲ß-D-galactopyranosyl -2-0- methyl-D-galactose, a galactosylgalactose composed of D and L-galactose, and adjacent 6-O̲-methyl- and 2-O̲-methyl-D- galactose units in the polysaccharide.
- Full Text:
- Date Issued: 1968
- Authors: Parolis, Haralambos
- Date: 1968
- Subjects: Polysaccharides , Marine algae -- Composition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4487 , http://hdl.handle.net/10962/d1012999
- Description: A highly sulphated, methylated polysaccharide, aeodan, isolated from the red seaweed Aeodes orbitosa was shown to contain galactose, 2-̲̲O-methyl-D-galactose, 4-O̲-methyl-Lgalactose, 6-O̲-methyl-D-galactose, xylose, and glycerol. The polysaccharide was desulphated with methanolic hydrogen chloride. Periodate oxidation of aeodan and desulphated aeodan, followed by reduction and hydrolysis, revealed the presence of 1,4- and 1,3-linked galactose residues and 1,3-linked 6-O̲-methy l-D-galactose residues in aeodan. Treatment of aeodan with sodium hydroxide revealed that the majority of the ester sulphate groups were alkali stable. Methylation of desulphated aeodan revealed that the polysaccharide was composed entirely of 1,3 and 1,4 links. Methylation of aeodan revealed the presence of 1,3- and 1,4- linked units, 1,3-linked galactose-2-sulphate, and 1,3-linked galactose-2, 6-disulphate units in the polysaccharide. Partial hydrolysis of aeodan resulted in the isolation and characterisation of 3-O̲-D-galactopyranosyl-D-galactose and 4-O̲-ß-D-galactopyranosyl- D-galactose. A sulphated, methylated polysaccharide, phyllymenan, isolated from the red seaweed Phyllymenia cornea was shown to contain galactose, 2-O̲-methyl-D-galactose, 4-O̲-methyl L- galactose , 6-O̲-methyl -D-galactose, and xylose. The polysaccharide was completely desulphated with methanolic hydrogen chloride. Periodate oxidation of phyllymenan before and after desulphation revealed that removal of the sulphate ester groups had not produced any new adjacent hydroxyl groups. Alkali treatment of phyllymenan revealed that the ester sulphate groups were alkali stable. Methylation studies on phyllymenan revealed the presence of 1,3- and 1,4-linked units, 1,3-linked galactose-2-sulphate, and 1,3-linked galactose- 2,6-disulphate units in the polysaccharide. Partial hydrolysis of phyllymenan revealed the presence or 4-O-̲ß- D-Dgalactopyranosyl- D-galactosc, 4-O-̲ß-D-galactopyranosyl -2-0- methyl-D-galactose, a galactosylgalactose composed of D and L-galactose, and adjacent 6-O̲-methyl- and 2-O̲-methyl-D- galactose units in the polysaccharide.
- Full Text:
- Date Issued: 1968
An investigation into the components of motivation so far as these determine employee stability and work satisfaction amongst Europeans and Africans engaged in the same occupational grading in the copper mining industry of Zambia
- Authors: Coetzee, J A G
- Date: 1968
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3383 , http://hdl.handle.net/10962/d1013334
- Description: From introduction: The aim of this study is to analyse the motivational system, so far as this regulates and orients the stability and work satisfactions of Europeans and Africans, in a supervisory occupational category engaged in industrial-mining in the Copper Mining Company of Rhokana, Zambia , during a period of six years, ending in 1963 .
- Full Text:
- Date Issued: 1968
- Authors: Coetzee, J A G
- Date: 1968
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3383 , http://hdl.handle.net/10962/d1013334
- Description: From introduction: The aim of this study is to analyse the motivational system, so far as this regulates and orients the stability and work satisfactions of Europeans and Africans, in a supervisory occupational category engaged in industrial-mining in the Copper Mining Company of Rhokana, Zambia , during a period of six years, ending in 1963 .
- Full Text:
- Date Issued: 1968
Death situations in the short story : a study in structure
- Authors: Ruthrof, Horst
- Date: 1968
- Subjects: Short story , Death in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2313 , http://hdl.handle.net/10962/d1013108
- Description: In an article on Ernst Cassirer, Konstantin Reichardt says, Since form is the only rational factor of every art, and the form of each art manifests a specific order, 'the order and form of the arts are to be investigated, if we want to examine the artist's imagination at work and the architecture of the world of art. It is the aim of this thesis to cast some light on a small, yet beautiful building within the complex architecture of this world of art, the genre of the short story. To isolate its structural and generic characteristics in general, however, would entail an analytical investigation into a huge number of short stcries, a task too great to be tackled in a thesis. Intro., p. 8.
- Full Text:
- Date Issued: 1968
- Authors: Ruthrof, Horst
- Date: 1968
- Subjects: Short story , Death in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2313 , http://hdl.handle.net/10962/d1013108
- Description: In an article on Ernst Cassirer, Konstantin Reichardt says, Since form is the only rational factor of every art, and the form of each art manifests a specific order, 'the order and form of the arts are to be investigated, if we want to examine the artist's imagination at work and the architecture of the world of art. It is the aim of this thesis to cast some light on a small, yet beautiful building within the complex architecture of this world of art, the genre of the short story. To isolate its structural and generic characteristics in general, however, would entail an analytical investigation into a huge number of short stcries, a task too great to be tackled in a thesis. Intro., p. 8.
- Full Text:
- Date Issued: 1968
Die sielkundige aanpassing van drie groepe Bantoes volgens die Rorschach toets
- Authors: Du Preez, Pieter Hendrik
- Date: 1968
- Subjects: Rorschach test Black people -- South Africa -- Psychology Ethnopsychology
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3203 , http://hdl.handle.net/10962/d1011495
- Description: Die huidige belangrike rol wat die Bantoe van Afrika in internasionale sake speel, is welbekend. So ook die belangrikheid van die Suid-Afrikaanse Bantoe. Hierdie belangrikheid van die Bantoe het egter verbasend skielik en vinnig gekom, so vinnig dat wetenskaplike kennis van hom as mens, nie kon tred hou nie, met die gevolg dat die beskaafde wereld hom swak ken. Die doel van hierdie proefskrif is dan ook om meer Iig te probeer werp op die persoonlikheid van die Bantoe en die lnvloed wat die snel veranderende omstandighede op hom uitoefen. Ten einde die maksimum waarde uit die Rorschach toets wat aangewend is, te verkry, is dlt nodig om beide die determinants berekenings sowel as die inhoudsanalise in berekening te bring. Vir navorsingsdoeleindes waar die resultate van verskeie proefpersone saamgevoeg word in verskiIlende groepe, is dit egter 'n moelIike taak om die gegewens kwantitatief hanteerbaar te kry. Dit is die rede waarom in hierdie studie van ordeskale gebruik gemaak is wat vir die doel heel doeltreffend blyk te gewees het.
- Full Text:
- Date Issued: 1968
- Authors: Du Preez, Pieter Hendrik
- Date: 1968
- Subjects: Rorschach test Black people -- South Africa -- Psychology Ethnopsychology
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3203 , http://hdl.handle.net/10962/d1011495
- Description: Die huidige belangrike rol wat die Bantoe van Afrika in internasionale sake speel, is welbekend. So ook die belangrikheid van die Suid-Afrikaanse Bantoe. Hierdie belangrikheid van die Bantoe het egter verbasend skielik en vinnig gekom, so vinnig dat wetenskaplike kennis van hom as mens, nie kon tred hou nie, met die gevolg dat die beskaafde wereld hom swak ken. Die doel van hierdie proefskrif is dan ook om meer Iig te probeer werp op die persoonlikheid van die Bantoe en die lnvloed wat die snel veranderende omstandighede op hom uitoefen. Ten einde die maksimum waarde uit die Rorschach toets wat aangewend is, te verkry, is dlt nodig om beide die determinants berekenings sowel as die inhoudsanalise in berekening te bring. Vir navorsingsdoeleindes waar die resultate van verskeie proefpersone saamgevoeg word in verskiIlende groepe, is dit egter 'n moelIike taak om die gegewens kwantitatief hanteerbaar te kry. Dit is die rede waarom in hierdie studie van ordeskale gebruik gemaak is wat vir die doel heel doeltreffend blyk te gewees het.
- Full Text:
- Date Issued: 1968
From myth to allegory: a study of the poetry of W.H. Auden, with special reference to the poet's intention
- Authors: Bell, I M
- Date: 1968
- Subjects: Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2290 , http://hdl.handle.net/10962/d1009514 , Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
- Description: The more attentively Auden's poetry is studied, the more one critical problem emerges. How can the poet of the "twenties and ' thirties be reconciled with the poet of the last three decades? "We've all got to come to terms with the later Auden" writes Professor Richard Hoggart, but he does not explain how. The man who wrote the pungent early poetry with its constant reiteration of warnings to a sick society that what was needed was " … death, death of the grain, our death, Death of the old gang … " before it could achieve "new styles of architecture, a change of heart", seems an entirely different person from the man who is on the side of Authority to-day; that is to say in so far as Auden can ever be said to be definitely on one side or another. Intro. p. 1.
- Full Text:
- Date Issued: 1968
- Authors: Bell, I M
- Date: 1968
- Subjects: Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2290 , http://hdl.handle.net/10962/d1009514 , Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
- Description: The more attentively Auden's poetry is studied, the more one critical problem emerges. How can the poet of the "twenties and ' thirties be reconciled with the poet of the last three decades? "We've all got to come to terms with the later Auden" writes Professor Richard Hoggart, but he does not explain how. The man who wrote the pungent early poetry with its constant reiteration of warnings to a sick society that what was needed was " … death, death of the grain, our death, Death of the old gang … " before it could achieve "new styles of architecture, a change of heart", seems an entirely different person from the man who is on the side of Authority to-day; that is to say in so far as Auden can ever be said to be definitely on one side or another. Intro. p. 1.
- Full Text:
- Date Issued: 1968
Government policy and industrial location in South Africa
- Authors: Bell, Robert Trevor
- Date: 1968
- Subjects: South Africa -- Industries -- Location Industrial relations -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1079 , http://hdl.handle.net/10962/d1009507
- Description: Governments, naturally, pursue social and political as well as economic objectives. The degree to which economic and non-economic objectives harmonise with one another without government interference, however, obviously varies a good deal according to time and place. For instance in the nineteenth century, the priorities of British governments made possible a high degree of individual freedom in the economic sphere. This century, however, as Robbins suggests, has seen a great extension of state activity in the economic sphere, for both economic and non-economic reasons. This tendency, then, is not peculiar to South Africa, but the border industries policy, largely because of its ideological associations and the degree of intervention which it seems to imply, is a particularly controversial example. Chapter 1 para 2.
- Full Text:
- Date Issued: 1968
- Authors: Bell, Robert Trevor
- Date: 1968
- Subjects: South Africa -- Industries -- Location Industrial relations -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1079 , http://hdl.handle.net/10962/d1009507
- Description: Governments, naturally, pursue social and political as well as economic objectives. The degree to which economic and non-economic objectives harmonise with one another without government interference, however, obviously varies a good deal according to time and place. For instance in the nineteenth century, the priorities of British governments made possible a high degree of individual freedom in the economic sphere. This century, however, as Robbins suggests, has seen a great extension of state activity in the economic sphere, for both economic and non-economic reasons. This tendency, then, is not peculiar to South Africa, but the border industries policy, largely because of its ideological associations and the degree of intervention which it seems to imply, is a particularly controversial example. Chapter 1 para 2.
- Full Text:
- Date Issued: 1968
Studies on the biology of the Cape chestnut psylla paurocephala Calodendri Moran (in press) and the South African citrus psylla Trioza Erytreae (Del Guercio) (Homoptera : Psyllidae)
- Authors: Moran, V C (V. Cliff)
- Date: 1968
- Subjects: Citrus -- Diseases and pests -- South Africa , Psylla
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5867 , http://hdl.handle.net/10962/d1012883
- Description: Citrus is grown as a commercial crop in several areas surrounding Grahamstown in the Eastern Cape Province of South Africa. Twelve miles South-west of Grahamstown is an orchard of about 6000 trees on the farm "Mosslands". This orchard attracted attention as the insect pests of citrus have been kept at a sub-economic level by natural biological control since 1949. This orchard is completely surrounded by indigenous bush and originally the object of this study was to see, in how far, the insect fauna of the indigenous bush was infuencing the biological control which had been achieved in the orchard. As citrus is a member of the family Rutaceae, four indigenous plants in this family, which occured in the indigenous bush, were chosen for a closer study of their associated insect fauna. This study continued for a year during which time a bewildering number of insects and their parasites were collected and it was realized that only an investigation of a very specific aspect of the problem could possibly yield meaningful results. As a starting point, therefore, Trioza erytreae (Del Guercio) (Homoptera: Psyllidae), the South African citrus psyllid, was singled out. This psyllid was found on citrus at "Mosslands" and was also found on all but one of the indigenous rutaceous plants. It was chosen for study because of its polyphagous habit and because very little is known of the biology of this economically important species in South Africa. Also very little work has been done on the Psyllidae generally. Intro., p. 1.
- Full Text:
- Date Issued: 1968
- Authors: Moran, V C (V. Cliff)
- Date: 1968
- Subjects: Citrus -- Diseases and pests -- South Africa , Psylla
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5867 , http://hdl.handle.net/10962/d1012883
- Description: Citrus is grown as a commercial crop in several areas surrounding Grahamstown in the Eastern Cape Province of South Africa. Twelve miles South-west of Grahamstown is an orchard of about 6000 trees on the farm "Mosslands". This orchard attracted attention as the insect pests of citrus have been kept at a sub-economic level by natural biological control since 1949. This orchard is completely surrounded by indigenous bush and originally the object of this study was to see, in how far, the insect fauna of the indigenous bush was infuencing the biological control which had been achieved in the orchard. As citrus is a member of the family Rutaceae, four indigenous plants in this family, which occured in the indigenous bush, were chosen for a closer study of their associated insect fauna. This study continued for a year during which time a bewildering number of insects and their parasites were collected and it was realized that only an investigation of a very specific aspect of the problem could possibly yield meaningful results. As a starting point, therefore, Trioza erytreae (Del Guercio) (Homoptera: Psyllidae), the South African citrus psyllid, was singled out. This psyllid was found on citrus at "Mosslands" and was also found on all but one of the indigenous rutaceous plants. It was chosen for study because of its polyphagous habit and because very little is known of the biology of this economically important species in South Africa. Also very little work has been done on the Psyllidae generally. Intro., p. 1.
- Full Text:
- Date Issued: 1968
The measurement of group differences in social concepts
- Authors: Morsbach, Gisela W L
- Date: 1968
- Subjects: Ethnic groups -- Psychology -- South Africa , Racism -- South Africa , Stereotypes (Social psychology) , Cross-cultural studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3218 , http://hdl.handle.net/10962/d1012907
- Description: The present study attempted a cross-cultural investigation of ethnic and national stereotypes in South Africa, a land inhabited by a heterogeneous population. In this country, real or imagined differences due to racial characteristics profoundly influence social interaction. Moreover, such differences are entrenched and underscored by the prevailing legal system while supplying the rationale for many actions of the goverru:tent in power. On the basis of relevant literature it was assumed that differentiation between stereotypes would be based mainly on colour, but that further distinctive differentiations would be present inside the ensuing major groupings ("White and "Non-White"). It was furthermore attempted to show that various groups differed significantly in their judgment of an ethnic stereotype only if they had a dissimilar relationship with the group to be judged. Altogether 760 subjects were tested. These belonged to the six major ethnic and cultural groups in South Africa (Africans, Afrikaners, Coloureds, English-speaking White Gentiles, Indians, and Jews). They were all asked to judge each one of ten concepts by means of the semantic differential technique, which consisted of twenty adjective pairs. Six of these concepts were the names of the South African groups mentioned above, while another three concepts represented the names of groups outside South Africa ("the Americans", "the Germans", and "the Russians") which play an important role in the thinking of South Africans. Finally, the subjects were asked to rate themselves ("Me"- concept). For the sake of better comparison, only first-year students were tested at various universities. The results were analyzed with the aid of a computer (the ICT computers at the University of Cape Town and at Rhodes University). Since a cross-cultural study rests on the theoretical assumption that any tests used for the purpose of comparison are reliable and valid in all cultures to be investigated, a few additional questions had to be asked. The checks undertaken confirmed that in the present study:- 1) The motivation of the subjects as well as their comprehension of the test's basic aims did not differ to any great extent. 2) The six groups did not differ appreciably as regards the social desirability of adjectives used, the semantic structure of the adjective pairs, and the range of scores on the adjective pairs. Furthermore, it was established that male-female differences in attitudes in each of the six groups tested were negligible. The stereotypes were compared with each other inside every one of the groups tested, as well as being compared between all the groups. These comparisons were carried out on the single adjective pairs separately (by means of the Sign Test and the Median Test), and then undertaken in the context of the factorial structure of the concepts. The major results showed that:- 1. The 'colour line' is an important criterion of evaluation in all groups but the Coloureds and the Jews. a) Apart from a 'Black Factor', on which the concepts "the Africans" and "the Coloureds" obtained high loadings, there appeared to be two factors dealing with the evaluation of the White groups. b) The evaluation of the 'Black Factor' by the African subjects was much more positive than the 'Black Factor' found in other groups. c) The Indian subjects did not regard themselves as belonging to the ' Non-Whites' ; neither were they regarded as such by the other subjects tested. 2. The criterion of colour was of less importance in the Coloured and Jewish groups tested. 3. The Jewish subjects appeared to possess the most differentiated stereotype structure, since, in their case, there were four, instead of the usual three factors to be extracted. Moreover, they tended to regard the Non-'White groups more positively than did the other two White groups. 4. The Afrikaans subjects held the most negative opinion of "the Africans"; conversely, "the Afrikaners" were also rejected more strongly than the English-speaking Whites by the Non-Whites tested. 5. Of all groups rated, "the Americans" were the most liked. 6. The stereotypes of "the Russians" and "the Germans" were fairly similar, except in the case of the Afrikaans subjects, who had an exceptionally positive regard for "the Germans". 1. Ratings of the subjects' own group were generally very much more positive than the ratings of the same group by members of other groups, except in the case of the English-speaking White Gentiles. 8. When any two groups rated a concept differently, this could generally be traced back to, on the one hand, differences in the relationships between each one of the judging groups, and, on the other, the group being judged. In conclusion it can be stated that differences between the groups as regards any one stereotype were generally smaller than the differences between the stereotypes of different concepts as held by any one group tested. Where no special relationships existed between a judging group and one being judged, ethnic and national stereotypes tended to be relatively similar in the various cultures and sub-cultures investigated.
- Full Text:
- Date Issued: 1968
- Authors: Morsbach, Gisela W L
- Date: 1968
- Subjects: Ethnic groups -- Psychology -- South Africa , Racism -- South Africa , Stereotypes (Social psychology) , Cross-cultural studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3218 , http://hdl.handle.net/10962/d1012907
- Description: The present study attempted a cross-cultural investigation of ethnic and national stereotypes in South Africa, a land inhabited by a heterogeneous population. In this country, real or imagined differences due to racial characteristics profoundly influence social interaction. Moreover, such differences are entrenched and underscored by the prevailing legal system while supplying the rationale for many actions of the goverru:tent in power. On the basis of relevant literature it was assumed that differentiation between stereotypes would be based mainly on colour, but that further distinctive differentiations would be present inside the ensuing major groupings ("White and "Non-White"). It was furthermore attempted to show that various groups differed significantly in their judgment of an ethnic stereotype only if they had a dissimilar relationship with the group to be judged. Altogether 760 subjects were tested. These belonged to the six major ethnic and cultural groups in South Africa (Africans, Afrikaners, Coloureds, English-speaking White Gentiles, Indians, and Jews). They were all asked to judge each one of ten concepts by means of the semantic differential technique, which consisted of twenty adjective pairs. Six of these concepts were the names of the South African groups mentioned above, while another three concepts represented the names of groups outside South Africa ("the Americans", "the Germans", and "the Russians") which play an important role in the thinking of South Africans. Finally, the subjects were asked to rate themselves ("Me"- concept). For the sake of better comparison, only first-year students were tested at various universities. The results were analyzed with the aid of a computer (the ICT computers at the University of Cape Town and at Rhodes University). Since a cross-cultural study rests on the theoretical assumption that any tests used for the purpose of comparison are reliable and valid in all cultures to be investigated, a few additional questions had to be asked. The checks undertaken confirmed that in the present study:- 1) The motivation of the subjects as well as their comprehension of the test's basic aims did not differ to any great extent. 2) The six groups did not differ appreciably as regards the social desirability of adjectives used, the semantic structure of the adjective pairs, and the range of scores on the adjective pairs. Furthermore, it was established that male-female differences in attitudes in each of the six groups tested were negligible. The stereotypes were compared with each other inside every one of the groups tested, as well as being compared between all the groups. These comparisons were carried out on the single adjective pairs separately (by means of the Sign Test and the Median Test), and then undertaken in the context of the factorial structure of the concepts. The major results showed that:- 1. The 'colour line' is an important criterion of evaluation in all groups but the Coloureds and the Jews. a) Apart from a 'Black Factor', on which the concepts "the Africans" and "the Coloureds" obtained high loadings, there appeared to be two factors dealing with the evaluation of the White groups. b) The evaluation of the 'Black Factor' by the African subjects was much more positive than the 'Black Factor' found in other groups. c) The Indian subjects did not regard themselves as belonging to the ' Non-Whites' ; neither were they regarded as such by the other subjects tested. 2. The criterion of colour was of less importance in the Coloured and Jewish groups tested. 3. The Jewish subjects appeared to possess the most differentiated stereotype structure, since, in their case, there were four, instead of the usual three factors to be extracted. Moreover, they tended to regard the Non-'White groups more positively than did the other two White groups. 4. The Afrikaans subjects held the most negative opinion of "the Africans"; conversely, "the Afrikaners" were also rejected more strongly than the English-speaking Whites by the Non-Whites tested. 5. Of all groups rated, "the Americans" were the most liked. 6. The stereotypes of "the Russians" and "the Germans" were fairly similar, except in the case of the Afrikaans subjects, who had an exceptionally positive regard for "the Germans". 1. Ratings of the subjects' own group were generally very much more positive than the ratings of the same group by members of other groups, except in the case of the English-speaking White Gentiles. 8. When any two groups rated a concept differently, this could generally be traced back to, on the one hand, differences in the relationships between each one of the judging groups, and, on the other, the group being judged. In conclusion it can be stated that differences between the groups as regards any one stereotype were generally smaller than the differences between the stereotypes of different concepts as held by any one group tested. Where no special relationships existed between a judging group and one being judged, ethnic and national stereotypes tended to be relatively similar in the various cultures and sub-cultures investigated.
- Full Text:
- Date Issued: 1968
A contribution to the biology of the sociable weaver Philetairus socius (Latham)
- Authors: Maclean, Gordon L
- Date: 1967
- Subjects: Weaverbirds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5863 , http://hdl.handle.net/10962/d1012791
- Description: Anyone who has travelled the dusty road in the bed of the Kuruman River from Kuruman in the Northern Cape to the South West African border at Rietfontein cannot fail to have been impressed by the large communal nests of the sociable weaver Philetairus socius which adorn many of the camelthorn trees along the way. One of the earliest reports of the bird and its nest is that of Sir Andrew Smith (1849) who passed that way through what was then Latakoo (the present day Kuruman), collecting birds which he described for the first time. To him we are indebted for the first published illustrations of the sociable weaver, its nest and egg, and a brief account, not entirely accurate to be sure, of the building and occupation of the nest. This account has since been quoted at length by Shelley (1905) and by Friedmann (1930a) who accepted Smith's statements as they stood. Some years after Smith's travels, Anderson wrote (1872) that the flocks of sociable weavers " ... incubate their eggs under the same roof, which is composed by these birds of whole cartloads of grass piled on a branch of some kamel-thorn tree in one enormous mass of an irregular umbrella-shape, looking like a miniature haystack, and almost solid, but with the under surface, which is nearly flat, honeycombed all over with little cavities, which serve not only as places for incubation but also as a refuge against rain and wind". This account gives some idea of the spectacular nests built by these birds which are hardly larger than a sparrow. But, living in the dry and thinly-populated western regions of southern Africa, the sociable weaver remained a remote curiosity, the subject of casual reports and some strange ideas. Since Friedmann (1930a) studied the sociable weaver briefly in the western Transvaal, the only thorough field observations (mainly on nests and nest sites) up to the present have been those of Rudebeck (1953, 1956). Collias & Collias (1964) returned to the western Transvaal some 20 years after Friedmann's visit, but unfortunately had time for only a cursory study; their main interest was once again in the nest and its architecture. Thus, in 1964 when I joined Dr. T.J. Cade, then of Syracuse University and now of Cornell University, on his desert biology programme, he suggested that the sociable weaver be the subject of special study in the Kalahari. Here was a bird, resident in a harsh environment, living throughout the year in an extraordinary nest, and almost completely unknown biologically. Among the questions to be answered were: How is the nest started and how is it constructed? Which birds build, and how is the labour organized? What is the purpose of the elaborate nest: does it provide a micro-climate which enables the birds to survive better under arid conditions? How could such a communal nest have evolved? What is the social organization of the colony in and out of the breeding season? When do the birds breed and what factors induce breeding? What happens to the young birds after they become independent of their parents? Naturally many other questions arose as the work proceeded, but these were the main ones on which the project was initiated.
- Full Text:
- Date Issued: 1967
- Authors: Maclean, Gordon L
- Date: 1967
- Subjects: Weaverbirds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5863 , http://hdl.handle.net/10962/d1012791
- Description: Anyone who has travelled the dusty road in the bed of the Kuruman River from Kuruman in the Northern Cape to the South West African border at Rietfontein cannot fail to have been impressed by the large communal nests of the sociable weaver Philetairus socius which adorn many of the camelthorn trees along the way. One of the earliest reports of the bird and its nest is that of Sir Andrew Smith (1849) who passed that way through what was then Latakoo (the present day Kuruman), collecting birds which he described for the first time. To him we are indebted for the first published illustrations of the sociable weaver, its nest and egg, and a brief account, not entirely accurate to be sure, of the building and occupation of the nest. This account has since been quoted at length by Shelley (1905) and by Friedmann (1930a) who accepted Smith's statements as they stood. Some years after Smith's travels, Anderson wrote (1872) that the flocks of sociable weavers " ... incubate their eggs under the same roof, which is composed by these birds of whole cartloads of grass piled on a branch of some kamel-thorn tree in one enormous mass of an irregular umbrella-shape, looking like a miniature haystack, and almost solid, but with the under surface, which is nearly flat, honeycombed all over with little cavities, which serve not only as places for incubation but also as a refuge against rain and wind". This account gives some idea of the spectacular nests built by these birds which are hardly larger than a sparrow. But, living in the dry and thinly-populated western regions of southern Africa, the sociable weaver remained a remote curiosity, the subject of casual reports and some strange ideas. Since Friedmann (1930a) studied the sociable weaver briefly in the western Transvaal, the only thorough field observations (mainly on nests and nest sites) up to the present have been those of Rudebeck (1953, 1956). Collias & Collias (1964) returned to the western Transvaal some 20 years after Friedmann's visit, but unfortunately had time for only a cursory study; their main interest was once again in the nest and its architecture. Thus, in 1964 when I joined Dr. T.J. Cade, then of Syracuse University and now of Cornell University, on his desert biology programme, he suggested that the sociable weaver be the subject of special study in the Kalahari. Here was a bird, resident in a harsh environment, living throughout the year in an extraordinary nest, and almost completely unknown biologically. Among the questions to be answered were: How is the nest started and how is it constructed? Which birds build, and how is the labour organized? What is the purpose of the elaborate nest: does it provide a micro-climate which enables the birds to survive better under arid conditions? How could such a communal nest have evolved? What is the social organization of the colony in and out of the breeding season? When do the birds breed and what factors induce breeding? What happens to the young birds after they become independent of their parents? Naturally many other questions arose as the work proceeded, but these were the main ones on which the project was initiated.
- Full Text:
- Date Issued: 1967
An investigation into the decametric radio emission by the planet Jupiter
- Authors: Gruber, Georg M
- Date: 1967
- Subjects: Jupiter (Planet) , Radio astronomy , Radio sources (Astronomy)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5545 , http://hdl.handle.net/10962/d1013410
- Description: From introduction: Jupiter is the largest planet in the solar system. Its distance from the Sun is five times that of the Earth and its mass is nearly two and a half times that of all the other planets added together. Jupiter turns about its own axis rather rapidly, once in just under ten hours, and it completes one revolution about the Sun in just under twelve years. Thus Earth has to pass almost directly between the Sun and Jupiter once every thirteen months. When this happens Jupiter is said to be in "opposition", as its position is then opposite to that of the Sun, when viewed from Earth. Around this time the planet will be most favourably placed for observations, as it is at its closest to Earth and up in the sky for a large part of the night. During the day observations on radio frequencies are more difficult, as the Sun is a source of great interference. Besides being an emitter of thermal electromagnetic radiation, as one would expect, Jupiter also emits two kinds of non-thermal radiation, one in the decimetre wavelength range and the other in the decametre wavelength range. A large number of scientists have worked on the problems of decimetre and decametre radiation. This thesis deals with some aspects of decametre radiation.
- Full Text:
- Date Issued: 1967
- Authors: Gruber, Georg M
- Date: 1967
- Subjects: Jupiter (Planet) , Radio astronomy , Radio sources (Astronomy)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5545 , http://hdl.handle.net/10962/d1013410
- Description: From introduction: Jupiter is the largest planet in the solar system. Its distance from the Sun is five times that of the Earth and its mass is nearly two and a half times that of all the other planets added together. Jupiter turns about its own axis rather rapidly, once in just under ten hours, and it completes one revolution about the Sun in just under twelve years. Thus Earth has to pass almost directly between the Sun and Jupiter once every thirteen months. When this happens Jupiter is said to be in "opposition", as its position is then opposite to that of the Sun, when viewed from Earth. Around this time the planet will be most favourably placed for observations, as it is at its closest to Earth and up in the sky for a large part of the night. During the day observations on radio frequencies are more difficult, as the Sun is a source of great interference. Besides being an emitter of thermal electromagnetic radiation, as one would expect, Jupiter also emits two kinds of non-thermal radiation, one in the decimetre wavelength range and the other in the decametre wavelength range. A large number of scientists have worked on the problems of decimetre and decametre radiation. This thesis deals with some aspects of decametre radiation.
- Full Text:
- Date Issued: 1967
Contributions to the ecology of the anomuran mud prawn Upogebia africana (Ortmann)
- Authors: Hill, Burke J
- Date: 1967
- Subjects: Decapoda , Shrimps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5888 , http://hdl.handle.net/10962/d1013341
- Description: Estuarine ecology in South Africa has progressed in two distinct stages. The first of these was a necessary descriptive phase which documented the general distribution of estuarine animals and recorded the physical conditions within estuaries . This phase has been carried out by the Zoology Department of the University of Cape Town which has made a series of ecological surveys of southern African estuaries. These surveys have provided a vast amount of valuable information which was utilised by Day (1964.) to state some general conclusions about estuarine faunas. The most important of these conclusions is that most of the estuarine fauna is really a quiet water fauna which also occurs in sheltered non-estuarine water. The information gained in this first stage is necessarily general and it can only indicate overall trends or reveal major features of distribution. Further estuary surveys are not justified unless they deal with unique conditions. It is at this point that the second phase of estuarine ecology becomes necessary. This phase involves a detailed investigation of individual species or particular problems. The present investigation falls into this second stage of estuarine ecology and was designed to extend our knowledge of the anomuran mud prawn Upogebia africana (Ortmann). The general estuarine surveys have shown that U. africana is a common inhabitant of many estuaries and sheltered bays along the southern African coast from Langebaan on the West coast to Inhambane on the East coast. However these surveys only revealed and could not explain anomalies in its distribution such as its apparent absence from closed estuaries and from estuaries in the tropics. In addition it was not even certain whether this abundant and widespread animal should really be considered a valid species distinct from a common West Coast prawn Upogebia capensis (Krauss). It was felt that a study of an estuarine species should be based upon a sound knowledge of its distribution, population structure and habitat. Knowledge of the habitat must be gained by studies in the field to establish which facets of the environment are of importance to the species. It was decided on the basis of field observations that temperature and salinity are of prime importance: in limiting the distribution of U. africana and a detailed laboratory study was therefore made of the tolerance of U. africana to these two physical factors. The results of laboratory experiments together with field observations were finally used to interpret the ecology of the species. Most of present day knowledge of crustacean ecology has been gained from a study of European and North American animals and information about southern hemisphere species has lagged behind. It is hoped that the present study will contribute to a wider understanding of Crustacea and that it will lead to further more advanced research on South African marine and estuarine animals
- Full Text:
- Date Issued: 1967
- Authors: Hill, Burke J
- Date: 1967
- Subjects: Decapoda , Shrimps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5888 , http://hdl.handle.net/10962/d1013341
- Description: Estuarine ecology in South Africa has progressed in two distinct stages. The first of these was a necessary descriptive phase which documented the general distribution of estuarine animals and recorded the physical conditions within estuaries . This phase has been carried out by the Zoology Department of the University of Cape Town which has made a series of ecological surveys of southern African estuaries. These surveys have provided a vast amount of valuable information which was utilised by Day (1964.) to state some general conclusions about estuarine faunas. The most important of these conclusions is that most of the estuarine fauna is really a quiet water fauna which also occurs in sheltered non-estuarine water. The information gained in this first stage is necessarily general and it can only indicate overall trends or reveal major features of distribution. Further estuary surveys are not justified unless they deal with unique conditions. It is at this point that the second phase of estuarine ecology becomes necessary. This phase involves a detailed investigation of individual species or particular problems. The present investigation falls into this second stage of estuarine ecology and was designed to extend our knowledge of the anomuran mud prawn Upogebia africana (Ortmann). The general estuarine surveys have shown that U. africana is a common inhabitant of many estuaries and sheltered bays along the southern African coast from Langebaan on the West coast to Inhambane on the East coast. However these surveys only revealed and could not explain anomalies in its distribution such as its apparent absence from closed estuaries and from estuaries in the tropics. In addition it was not even certain whether this abundant and widespread animal should really be considered a valid species distinct from a common West Coast prawn Upogebia capensis (Krauss). It was felt that a study of an estuarine species should be based upon a sound knowledge of its distribution, population structure and habitat. Knowledge of the habitat must be gained by studies in the field to establish which facets of the environment are of importance to the species. It was decided on the basis of field observations that temperature and salinity are of prime importance: in limiting the distribution of U. africana and a detailed laboratory study was therefore made of the tolerance of U. africana to these two physical factors. The results of laboratory experiments together with field observations were finally used to interpret the ecology of the species. Most of present day knowledge of crustacean ecology has been gained from a study of European and North American animals and information about southern hemisphere species has lagged behind. It is hoped that the present study will contribute to a wider understanding of Crustacea and that it will lead to further more advanced research on South African marine and estuarine animals
- Full Text:
- Date Issued: 1967
Hydrobiological studies on the Vaal River and some of its tributaries, including an introduction to the ecology of Simulium in its lower reaches
- Authors: Chutter, F M
- Date: 1967
- Subjects: Freshwater biology Freshwater animals Freshwater ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5841 , http://hdl.handle.net/10962/d1010499
- Description: The studies on the Vaal River and its tributaries presented here, were carried out for a variety of reasons. Prominent among them were several of immediate practical importance, such as the need to know the pollution status of waters which ultimately form the major supply for the Witwatersrand urban and industrial complex, and the need for background data on a stretch of the river which was to be insecticided to control a Simulium pest. However the results of such work can often be used for wider purposes. In this thesis they are used to examine the major factors thought to govern the distribution and abundance of the invertebrate Metazoa in the river. Introduction, p. 2-3.
- Full Text:
- Date Issued: 1967
- Authors: Chutter, F M
- Date: 1967
- Subjects: Freshwater biology Freshwater animals Freshwater ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5841 , http://hdl.handle.net/10962/d1010499
- Description: The studies on the Vaal River and its tributaries presented here, were carried out for a variety of reasons. Prominent among them were several of immediate practical importance, such as the need to know the pollution status of waters which ultimately form the major supply for the Witwatersrand urban and industrial complex, and the need for background data on a stretch of the river which was to be insecticided to control a Simulium pest. However the results of such work can often be used for wider purposes. In this thesis they are used to examine the major factors thought to govern the distribution and abundance of the invertebrate Metazoa in the river. Introduction, p. 2-3.
- Full Text:
- Date Issued: 1967
Synthesis of flavan-3, 4-diols, stereochemistry of novel biflavanols and new non-tannins from Acacia Mearnsii
- Authors: Saayman, Henry Martin
- Date: 1967
- Subjects: Tannins Acacia mearnsii Stereochemistry Wattles (Plants) Chemistry, Analytic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4444 , http://hdl.handle.net/10962/d1007704
- Description: From Summary: The structural elucidation of condensed tannins, which are considered to consist of C₁₅-flavan units, presents certain difficulties. These tannins occur in extremely complex mixtures, and their isolation is complicated by their susceptibility to oxidative denaturation. Limitations in the formation of significant degradation products add to these problems. Since condensed tannins of black wattle bark yield anthocyanidins on treatment with mineral acids, they are considered to be proanthocyanidin in character. For this reason the initial approach to the investigation of the structures of condensed tannins was by way of the synthesis of novel 7-hydroxyflavan-3,4-diols having a low degree of hydroxyl substitution. Submission of these to modern physical techniques such as nuclear magnetic resonance (n.m.r.) spectroscopy would yield valuable data regarding the chemical shifts and coupling constants of heterocyclic and benzenoid protons which may be used for subsequent work on more highly hydroxylated diols, biflavanols and finally the condensed tannins themselves.
- Full Text:
- Date Issued: 1967
- Authors: Saayman, Henry Martin
- Date: 1967
- Subjects: Tannins Acacia mearnsii Stereochemistry Wattles (Plants) Chemistry, Analytic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4444 , http://hdl.handle.net/10962/d1007704
- Description: From Summary: The structural elucidation of condensed tannins, which are considered to consist of C₁₅-flavan units, presents certain difficulties. These tannins occur in extremely complex mixtures, and their isolation is complicated by their susceptibility to oxidative denaturation. Limitations in the formation of significant degradation products add to these problems. Since condensed tannins of black wattle bark yield anthocyanidins on treatment with mineral acids, they are considered to be proanthocyanidin in character. For this reason the initial approach to the investigation of the structures of condensed tannins was by way of the synthesis of novel 7-hydroxyflavan-3,4-diols having a low degree of hydroxyl substitution. Submission of these to modern physical techniques such as nuclear magnetic resonance (n.m.r.) spectroscopy would yield valuable data regarding the chemical shifts and coupling constants of heterocyclic and benzenoid protons which may be used for subsequent work on more highly hydroxylated diols, biflavanols and finally the condensed tannins themselves.
- Full Text:
- Date Issued: 1967