A preliminary study of adaptation and inhibition of reflex claw opening in the crab Potamon perlatus (Milne Edwards)
- Authors: Bush, Brian M H
- Date: 1956
- Subjects: Crabs , Decapoda
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5906 , http://hdl.handle.net/10962/d1014683
- Description: The only recorded experimental attempt to determine the functional, biological significance of peripheral inhibition in the Crustacea is that of Hoffmann (1914). From a series of experiments on Astacus fluviatilis L. involving transsection of the opener inhibitor and motor axons of the cheliped, he concluded that the opener inhibitor axon of the claw responded to prolonged or repeated sensory stimulation by transmitting inhibitory impulses to the opener muscle, the peripheral inhibition thus evoked causing adaptation of the reflex opening responses of the claw to the sensory stimulation. This suggests that there may be (1) a very high degree of peripheral control of (a) the reactions of the animal to external stimuli, and perhaps also to proprioceptive stimuli, and therefore (b) of the behaviour of the animal; and (2) a correspondingly high degree of independence of this behaviour from central nervous control. It is therefore of importance to discover whether, in fact, this conclusion is valid for Astacus and other Decapod Crustacea, and if so, then to what extent the adaptation is peripherally controlled. A preliminary attempt haa been made to repeat these experiments of Hoffmann, using Potamon perlatus (M.Edw.). Experiments in which mechanical sensory stimulation was used to evoke reflex claw opening indicated that this conclusion is not applicable to P.perlatus. The adaptation of the mechanical claw openining responses which occurred with repeated sensory stimulation was not affected by transsection of either the specific opener inhibitor axon or the common inhibitor axon of the claw. It was evidently mainly due to sensory adaptation when the sensory stimuli were heavy, and to centrally controlled adaptation when the sensory stimuli were light. The significance of these results is discussed. Other effects observed during the course of the work, of electrical "sensory" stimulation, and of cerebral ganglion elimination, are also described and discussed in relation to the present problem.
- Full Text:
- Date Issued: 1956
- Authors: Bush, Brian M H
- Date: 1956
- Subjects: Crabs , Decapoda
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5906 , http://hdl.handle.net/10962/d1014683
- Description: The only recorded experimental attempt to determine the functional, biological significance of peripheral inhibition in the Crustacea is that of Hoffmann (1914). From a series of experiments on Astacus fluviatilis L. involving transsection of the opener inhibitor and motor axons of the cheliped, he concluded that the opener inhibitor axon of the claw responded to prolonged or repeated sensory stimulation by transmitting inhibitory impulses to the opener muscle, the peripheral inhibition thus evoked causing adaptation of the reflex opening responses of the claw to the sensory stimulation. This suggests that there may be (1) a very high degree of peripheral control of (a) the reactions of the animal to external stimuli, and perhaps also to proprioceptive stimuli, and therefore (b) of the behaviour of the animal; and (2) a correspondingly high degree of independence of this behaviour from central nervous control. It is therefore of importance to discover whether, in fact, this conclusion is valid for Astacus and other Decapod Crustacea, and if so, then to what extent the adaptation is peripherally controlled. A preliminary attempt haa been made to repeat these experiments of Hoffmann, using Potamon perlatus (M.Edw.). Experiments in which mechanical sensory stimulation was used to evoke reflex claw opening indicated that this conclusion is not applicable to P.perlatus. The adaptation of the mechanical claw openining responses which occurred with repeated sensory stimulation was not affected by transsection of either the specific opener inhibitor axon or the common inhibitor axon of the claw. It was evidently mainly due to sensory adaptation when the sensory stimuli were heavy, and to centrally controlled adaptation when the sensory stimuli were light. The significance of these results is discussed. Other effects observed during the course of the work, of electrical "sensory" stimulation, and of cerebral ganglion elimination, are also described and discussed in relation to the present problem.
- Full Text:
- Date Issued: 1956
Robert Godlonton as architect of frontier opinion, with special reference to the politics of separatism, 1850-57
- Authors: Le Cordeur, Basil Alexander
- Date: 1956
- Subjects: Godlonton, Robert, 1794-1884 , Cape of Good Hope (South Africa) -- History -- 1795-1872 , Cape of Good Hope (South Africa) -- Politics and government -- 1795-1872 , Press and politics -- South Africa -- Cape of Good Hope , Editors -- South Africa -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2619 , http://hdl.handle.net/10962/d1013497
- Description: [Preface] The broad outlines of Cape frontier historiography have so far been sketched from a study of official despatches and, to a lesser extent, of contemporary newspapers. There are many lacunae to be filled and many questions to be answered; here, it is evident that private papers have an indispensable role to play. Yet, despite isolated attempts to collect or index such papers, (such as that of Miss Una Long, in her Index to Unofficial, Privately-Owned Manuscripts relating to the history of South Africa), much untapped material still remains in private possession both in South Africa and overseas. In this study of a leading Eastern Province personality, prominence has been given to this type of material, and much of what has been used, has clearly not previoualy been examined by historians.
- Full Text:
- Date Issued: 1956
- Authors: Le Cordeur, Basil Alexander
- Date: 1956
- Subjects: Godlonton, Robert, 1794-1884 , Cape of Good Hope (South Africa) -- History -- 1795-1872 , Cape of Good Hope (South Africa) -- Politics and government -- 1795-1872 , Press and politics -- South Africa -- Cape of Good Hope , Editors -- South Africa -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2619 , http://hdl.handle.net/10962/d1013497
- Description: [Preface] The broad outlines of Cape frontier historiography have so far been sketched from a study of official despatches and, to a lesser extent, of contemporary newspapers. There are many lacunae to be filled and many questions to be answered; here, it is evident that private papers have an indispensable role to play. Yet, despite isolated attempts to collect or index such papers, (such as that of Miss Una Long, in her Index to Unofficial, Privately-Owned Manuscripts relating to the history of South Africa), much untapped material still remains in private possession both in South Africa and overseas. In this study of a leading Eastern Province personality, prominence has been given to this type of material, and much of what has been used, has clearly not previoualy been examined by historians.
- Full Text:
- Date Issued: 1956
Scientific management as applied to a South African sweet factory
- Authors: Bernstein, Jack
- Date: 1956
- Subjects: Candy industry -- Management , Candy industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1111 , http://hdl.handle.net/10962/d1013494
- Description: From Chapter 1: Among the many problems that the sweet industry in this country has had to overcome was the prejudice which favoured imported confectionery as against the local product. Fortunately this prejudice is slowly disappearing, firstly because imported sweets are largely unobtainable, and, secondly because the quality of the South African manufactured article has improved tremendously. Both the quantity and value of sweets produced in this country have increased over the last decade...
- Full Text:
- Date Issued: 1956
- Authors: Bernstein, Jack
- Date: 1956
- Subjects: Candy industry -- Management , Candy industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:1111 , http://hdl.handle.net/10962/d1013494
- Description: From Chapter 1: Among the many problems that the sweet industry in this country has had to overcome was the prejudice which favoured imported confectionery as against the local product. Fortunately this prejudice is slowly disappearing, firstly because imported sweets are largely unobtainable, and, secondly because the quality of the South African manufactured article has improved tremendously. Both the quantity and value of sweets produced in this country have increased over the last decade...
- Full Text:
- Date Issued: 1956
Some aspects of the micro-arthropod fauna in the soils of pineapple fields in the Bathurst division, Eastern Cape Province
- Authors: Graham, P
- Date: 1956
- Subjects: Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5853 , http://hdl.handle.net/10962/d1012087 , Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
- Description: Although a considerable amount of work has been done on the fauna of the soil of temperate forests and pastures, very little is known about that of tropical and sub-tropical soils. Most of the work on tropical soils concerns the fauna of tropical forests ... . The present investigation represents an attempt to discover the effect of an imported perennial tropical and sub-tropical plant, the Pineapple, on the soil fauna of a semi-arid region (rainfall 15-25 inches). Intro., p. 1-2
- Full Text:
- Date Issued: 1956
- Authors: Graham, P
- Date: 1956
- Subjects: Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5853 , http://hdl.handle.net/10962/d1012087 , Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
- Description: Although a considerable amount of work has been done on the fauna of the soil of temperate forests and pastures, very little is known about that of tropical and sub-tropical soils. Most of the work on tropical soils concerns the fauna of tropical forests ... . The present investigation represents an attempt to discover the effect of an imported perennial tropical and sub-tropical plant, the Pineapple, on the soil fauna of a semi-arid region (rainfall 15-25 inches). Intro., p. 1-2
- Full Text:
- Date Issued: 1956
The fungal flora associated with black spot of pineapples
- Authors: Edmonstone-Sammons, Chloris
- Date: 1956
- Subjects: Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4258 , http://hdl.handle.net/10962/d1011738 , Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
- Description: The earliest reference to investigations of "black spot" in pineapples is made by Tryon (1898), who refers to the work of Dr A. A. Brown (1896) of the stock Branch, Victoria (Aus.), who sectioned diseased areas of pineapples and found fungal spores and hyphae in the tissues. The symptoms of this socalled "fruitlet core rot," are described by Tryon as: "well defined dark brown markings immediately beneath the surface, and passing inwards to a depth of 1/4" to 1/2"- the malady commencing in separate fruitlets, the central core of the fruit remaining quite healthy." (This description agrees with the symptoms referred to as "black spot" 1n this country). Subsequent culture of the spores (found by Brown) on slices of healthy fruit resulted in growth of Mucor racemosus. Brown regarded an invasion by this fungus as a primary cause of the disease. Intro. p. 1.
- Full Text:
- Date Issued: 1956
- Authors: Edmonstone-Sammons, Chloris
- Date: 1956
- Subjects: Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4258 , http://hdl.handle.net/10962/d1011738 , Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
- Description: The earliest reference to investigations of "black spot" in pineapples is made by Tryon (1898), who refers to the work of Dr A. A. Brown (1896) of the stock Branch, Victoria (Aus.), who sectioned diseased areas of pineapples and found fungal spores and hyphae in the tissues. The symptoms of this socalled "fruitlet core rot," are described by Tryon as: "well defined dark brown markings immediately beneath the surface, and passing inwards to a depth of 1/4" to 1/2"- the malady commencing in separate fruitlets, the central core of the fruit remaining quite healthy." (This description agrees with the symptoms referred to as "black spot" 1n this country). Subsequent culture of the spores (found by Brown) on slices of healthy fruit resulted in growth of Mucor racemosus. Brown regarded an invasion by this fungus as a primary cause of the disease. Intro. p. 1.
- Full Text:
- Date Issued: 1956
The voluntary welfare organisations of the Border and Transkei: a contribution to the sociology of social work
- Authors: Bettison, D G
- Date: 1956
- Subjects: Social service -- South Africa -- Transkei Social service -- South Africa -- Eastern Cape Volunteer workers in social service
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3314 , http://hdl.handle.net/10962/d1003102
- Description: This research is intended to examine the internal organisational structure of the existing [voluntary welfare] organisations to ascertain what relationship may prove effective between themselves and the [Border Local Welfare] Board. This aim introduced the need to ascertain whether a) the organisations in any town were connected with organisations in other towns or to a central administrative office either in the area of investigation or outside it; or b) the organisations of any town were simply ad hoc units unrelated to any other organisation or similar organisations elsewhere. If the latter were the case then the difficulty of co-ordination and representation on the Board could probably be no better arranged than an ad hoc system as at present. If, however, the former was the predominant pattern, then it would suggest other and more convenient means to the end in view. Fourthly, it was hoped to gain some knowledge of the fund raising methods of welfare organisations, the nature of the people controlling them, the attitudes of managing committees to social work, and what they thought a case work agency should do; and, lastly, some indication of the history of social work as practised by the voluntary agencies in the area of investigation. These latter topics were not intended to form the principal subject matter of the work. They have not been treated fully in the text, but the information gathered has been included in appropriate places throughout.
- Full Text:
- Date Issued: 1956
- Authors: Bettison, D G
- Date: 1956
- Subjects: Social service -- South Africa -- Transkei Social service -- South Africa -- Eastern Cape Volunteer workers in social service
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3314 , http://hdl.handle.net/10962/d1003102
- Description: This research is intended to examine the internal organisational structure of the existing [voluntary welfare] organisations to ascertain what relationship may prove effective between themselves and the [Border Local Welfare] Board. This aim introduced the need to ascertain whether a) the organisations in any town were connected with organisations in other towns or to a central administrative office either in the area of investigation or outside it; or b) the organisations of any town were simply ad hoc units unrelated to any other organisation or similar organisations elsewhere. If the latter were the case then the difficulty of co-ordination and representation on the Board could probably be no better arranged than an ad hoc system as at present. If, however, the former was the predominant pattern, then it would suggest other and more convenient means to the end in view. Fourthly, it was hoped to gain some knowledge of the fund raising methods of welfare organisations, the nature of the people controlling them, the attitudes of managing committees to social work, and what they thought a case work agency should do; and, lastly, some indication of the history of social work as practised by the voluntary agencies in the area of investigation. These latter topics were not intended to form the principal subject matter of the work. They have not been treated fully in the text, but the information gathered has been included in appropriate places throughout.
- Full Text:
- Date Issued: 1956
A conductimetric investigation of phenomena in extremely dilute aqueous solutions
- Authors: Faure, Pierre Knobel
- Date: 1957
- Subjects: Adsorption , Solution (Chemistry)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4524 , http://hdl.handle.net/10962/d1014891
- Description: 1. The apparatus used in this investigation is fully described, and a new method is outlined for the calibration of bridge resistances "in situ". 2. A chart is given for the accurate correction of weights in air to weights in vacuum for a range of temperatures extending from 10° to 28°C, and for pressures from 690 to 730 mm. 3. An automatic recycling still has been designed for the continuous production of "ultra-pure" water. This still is capable of delivering daily, in routine operation, 16 l. of water of conductivity less than 100 nm/cm after aeration with "C0₂- and NH₃-free" air. 4. A very soluble layer appears to form on the surface of' glass when it is dried; this layer is readily removed on contact with water. 5. The removal of carbon dioxide and of ammonia from aqueous solution by aeration with an indifferent gas has been fully investigated, and it has been shown that these gases can be completely eliminated by such a process. Whereas the carbon dioxide is removed fairly rapidly, however, the ammonia, whether present alone or together with carbon dioxide, only goes out of solution rather slowly. 6. It has been shown that ammonia is adsorbed from aqueous solution on the glass walls of the cell. 7. There does not appear to be any ammonium bicarbonate in the residual impurity left in the "ultra-pure" water obtained from the still; the impurity can, in fact, be regarded as neutral salt with sufficient accuracy for most purposes. 8. The resistance change which accompanies any variation in the rate of bubbling of the stirring gas through the water has been investigated, but no solution has been found as to the cause of this change. 9. A comparison has been made of the efficiency of different gases for stirring purposes, and it seems that, for general work, nitrogen is by far the most suitable of the common gases. 10. The extrapolation to be used for converting resistances to their values at infinite frequency appears ...
- Full Text:
- Date Issued: 1957
- Authors: Faure, Pierre Knobel
- Date: 1957
- Subjects: Adsorption , Solution (Chemistry)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4524 , http://hdl.handle.net/10962/d1014891
- Description: 1. The apparatus used in this investigation is fully described, and a new method is outlined for the calibration of bridge resistances "in situ". 2. A chart is given for the accurate correction of weights in air to weights in vacuum for a range of temperatures extending from 10° to 28°C, and for pressures from 690 to 730 mm. 3. An automatic recycling still has been designed for the continuous production of "ultra-pure" water. This still is capable of delivering daily, in routine operation, 16 l. of water of conductivity less than 100 nm/cm after aeration with "C0₂- and NH₃-free" air. 4. A very soluble layer appears to form on the surface of' glass when it is dried; this layer is readily removed on contact with water. 5. The removal of carbon dioxide and of ammonia from aqueous solution by aeration with an indifferent gas has been fully investigated, and it has been shown that these gases can be completely eliminated by such a process. Whereas the carbon dioxide is removed fairly rapidly, however, the ammonia, whether present alone or together with carbon dioxide, only goes out of solution rather slowly. 6. It has been shown that ammonia is adsorbed from aqueous solution on the glass walls of the cell. 7. There does not appear to be any ammonium bicarbonate in the residual impurity left in the "ultra-pure" water obtained from the still; the impurity can, in fact, be regarded as neutral salt with sufficient accuracy for most purposes. 8. The resistance change which accompanies any variation in the rate of bubbling of the stirring gas through the water has been investigated, but no solution has been found as to the cause of this change. 9. A comparison has been made of the efficiency of different gases for stirring purposes, and it seems that, for general work, nitrogen is by far the most suitable of the common gases. 10. The extrapolation to be used for converting resistances to their values at infinite frequency appears ...
- Full Text:
- Date Issued: 1957
Liquid junction potentials at mixed electrolyte salt bridges
- Authors: Finkelstein, Noel Phillip
- Date: 1957
- Subjects: Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4473 , http://hdl.handle.net/10962/d1011835 , Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
- Description: The potentiometric method is one of the most exact techniques of electrochemistry. Its use is widespread in both routine measurements, such as pH determination, and in applications which demand the highest accuracy. Perhaps its severest limitation is the error due to liquid junction potentials. Although this has been the subject of much study, and although various means of combating it have been proposed, it has defied all attempts at a satisfactory solution. Indeed, so serious is the position that it has become the accepted practice in the more accurate fields to abandon altogether the use of potentiometric techniques in favour of others, usually less convenient and otherwise less accurate, when the presence of liquid junctions cannot be avoided. Intro. p. 1.
- Full Text:
- Date Issued: 1957
- Authors: Finkelstein, Noel Phillip
- Date: 1957
- Subjects: Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4473 , http://hdl.handle.net/10962/d1011835 , Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
- Description: The potentiometric method is one of the most exact techniques of electrochemistry. Its use is widespread in both routine measurements, such as pH determination, and in applications which demand the highest accuracy. Perhaps its severest limitation is the error due to liquid junction potentials. Although this has been the subject of much study, and although various means of combating it have been proposed, it has defied all attempts at a satisfactory solution. Indeed, so serious is the position that it has become the accepted practice in the more accurate fields to abandon altogether the use of potentiometric techniques in favour of others, usually less convenient and otherwise less accurate, when the presence of liquid junctions cannot be avoided. Intro. p. 1.
- Full Text:
- Date Issued: 1957
Photofluorescence decay times of organic phosphors
- Authors: Hamilton, T D S
- Date: 1957
- Subjects: Fluorescence , Phosphorescence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5525 , http://hdl.handle.net/10962/d1012136 , Fluorescence , Phosphorescence
- Description: The absorption and emission of energy is a fundamental property of any atomic system.When the emission occurs in the visible or near visible region the phenomenon is usually referred to as luminescence or fluorescence. This must be distinguished from thermal radiation as it does not follow Kirchoff's law.
- Full Text:
- Date Issued: 1957
- Authors: Hamilton, T D S
- Date: 1957
- Subjects: Fluorescence , Phosphorescence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5525 , http://hdl.handle.net/10962/d1012136 , Fluorescence , Phosphorescence
- Description: The absorption and emission of energy is a fundamental property of any atomic system.When the emission occurs in the visible or near visible region the phenomenon is usually referred to as luminescence or fluorescence. This must be distinguished from thermal radiation as it does not follow Kirchoff's law.
- Full Text:
- Date Issued: 1957
Some aspects of the animal ecology of Rhenosterbos: Elytropappus rhinocerotis (L.f.) Less
- Authors: Shiff, Clive Julian
- Date: 1957
- Subjects: Animal ecology -- South Africa , Rhenosterbos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5880 , http://hdl.handle.net/10962/d1013200
- Description: Rhenosterbos, Elytropappus rhinocerotis (L.f.) Less belongs to a purely South African section ot the Compositae. It is restricted to an area of low rainfall which is evenly distributed over the year. The plant is a specialised xerophyte with minute leaves and white pubescent twiglets. Older stems become woody and dry and bear no leaves. The shrubs have a life span of about eight years; the plants are most succulent and luxurious during the third and fourth year, after which they tend to become woody and scraggly. For this investigation insect material was obtained by sweep-net collection and field observation. In the Grahamatown district 78 collections were made during the period March - November 1953, with data thus obtained being embodied in this work. In addition to this, collections were made in the Cradock-Hofmeyer, Uitenhage, Riversdale, Bot River, Swellendam and Stellenbosch districts. Twenty species of insects have been shown definitely to feed on the plant and there are another 13 which probably feed on it. Of the 20 species attached to the plant, 12 are sucking forms belonging to the Orders Homoptera and Hemipters. They include six Coccids, two Jassids a Cercopid, two Mirids and a Pentstomid. The Coleoptera are represented by one or perhaps two species which feed on the plant. The Lepidoptera are represented by two important species of moth, a Geometrid and a Pyralid. Four species of gall forming Diptera are associated with the plant. There are two species of Trypetidae which are responsible for piriform swellings of growth points and are distributed evenly throughout the bush. There are also two Cecidomyidae one of which develops in the growth points of the shoots and is responsible tor a minute tubular gall. The other develops in a fusiform stem gall. This latter gall has been shown to be more common on smaller bushes than on larger ones, implying that the adult female may show certain selective powers during oviposition. The size of the insect population is held in check by spiders mantids and other general predators. There are several Coccinellids which prey on the scale insects. Rhenosterbos supports a small, well regulated community of insects. The balance between plant and animal is very dellcate because of the high degree of specialisation of the plant. On occasions this balance has been known to break down, and the insects present in abundance have swamped and killed large patches of the plant.
- Full Text:
- Date Issued: 1957
- Authors: Shiff, Clive Julian
- Date: 1957
- Subjects: Animal ecology -- South Africa , Rhenosterbos
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5880 , http://hdl.handle.net/10962/d1013200
- Description: Rhenosterbos, Elytropappus rhinocerotis (L.f.) Less belongs to a purely South African section ot the Compositae. It is restricted to an area of low rainfall which is evenly distributed over the year. The plant is a specialised xerophyte with minute leaves and white pubescent twiglets. Older stems become woody and dry and bear no leaves. The shrubs have a life span of about eight years; the plants are most succulent and luxurious during the third and fourth year, after which they tend to become woody and scraggly. For this investigation insect material was obtained by sweep-net collection and field observation. In the Grahamatown district 78 collections were made during the period March - November 1953, with data thus obtained being embodied in this work. In addition to this, collections were made in the Cradock-Hofmeyer, Uitenhage, Riversdale, Bot River, Swellendam and Stellenbosch districts. Twenty species of insects have been shown definitely to feed on the plant and there are another 13 which probably feed on it. Of the 20 species attached to the plant, 12 are sucking forms belonging to the Orders Homoptera and Hemipters. They include six Coccids, two Jassids a Cercopid, two Mirids and a Pentstomid. The Coleoptera are represented by one or perhaps two species which feed on the plant. The Lepidoptera are represented by two important species of moth, a Geometrid and a Pyralid. Four species of gall forming Diptera are associated with the plant. There are two species of Trypetidae which are responsible for piriform swellings of growth points and are distributed evenly throughout the bush. There are also two Cecidomyidae one of which develops in the growth points of the shoots and is responsible tor a minute tubular gall. The other develops in a fusiform stem gall. This latter gall has been shown to be more common on smaller bushes than on larger ones, implying that the adult female may show certain selective powers during oviposition. The size of the insect population is held in check by spiders mantids and other general predators. There are several Coccinellids which prey on the scale insects. Rhenosterbos supports a small, well regulated community of insects. The balance between plant and animal is very dellcate because of the high degree of specialisation of the plant. On occasions this balance has been known to break down, and the insects present in abundance have swamped and killed large patches of the plant.
- Full Text:
- Date Issued: 1957
Studies on the biology of ants associated with citrus trees
- Authors: Myers, N J
- Date: 1957
- Subjects: Citrus -- Diseases and pests -- Biological control -- South Africa , Ants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5869 , http://hdl.handle.net/10962/d1012923
- Description: Several ant species may be associated with the same honeydew producing insect in citrus orchards. Recently antagonism and competition between two such ants were reported from Letaba. This report stimulated the present study, the purpose of which is to ascertain which ant species are most numerous in citrus orchards ln the Eastern Cape Province; the reasons for these ants being able to occupy orchards; and, finally, their relationships. A survey of the Sundays River Valley and the Fish River Valley revealed that three species - Anoplolepis custodiens Smith, Anoplolepis steingroeveri Forel, and Pheidole megacephala Fabricius - were commonly found in citrus orchards in association with Soft Brown Scale insects. The territorial relationships of these ants were determined by plotting their distribution at intervals for over a year. It was found that this distribution could be correlated with seasonal climatic conditions, the effects of farming practices, brood rearing requirements and behavioural differences between the three species. The ant, A.steingroeveri, had not been previously studied, and since foraging is an integral part of territorial behaviour, some aspects of its biology, and more especially its foraging activity, were investigated to compare it with the known biology of the other two species. Observations on the foraging activity of A. steingroeveri were made at monthly lntervals for almost a year, and correlated with climatic conditions prevailing at the time. Some seasonal and dally variations in foraging behaviour could not be readily explained in terms of the effects of temperature and humidity on the ants. Other factors, includ1ng trophallactic stimulation and overcast skies, were found to influence ant activity. Owing to the apparent lack of information in the literature and possibility of periodic honeydew production by Soft Brown Scale insects controlling ant activity was investigated in the laboratory. The results of this study showed that it was not likely that honeydew excretion restricted the activity of the ants. Several investigators have also found that many interrelated climatic factors correlated with ant foraging behaviour, but have expressed dissatisfaction at not being able to reach the crux of the matter. To clarify the issue a constant temperature chamber was constructed in which a colony of Crematogaster ants was housed and the ants were subjected to a series of temperatures at different humidities, all other factors were eliminated or kept constant. The effects of these two factors on the thermokinetics and foraging activity of the ants were registered. This thesis contains several sections and at the end of each the results are discussed in the light of the available literature and comparisons are drawn between the species under investigation. The main results are given in the summary. After the summary two appendices are included. One is an attempt to compare the effect on ant size of the honeydew diet of orchard colonies with the proteinaceoue diet of veld ants. The other appendix is an experiment to control citrus ants with an insecticide.
- Full Text:
- Date Issued: 1957
- Authors: Myers, N J
- Date: 1957
- Subjects: Citrus -- Diseases and pests -- Biological control -- South Africa , Ants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5869 , http://hdl.handle.net/10962/d1012923
- Description: Several ant species may be associated with the same honeydew producing insect in citrus orchards. Recently antagonism and competition between two such ants were reported from Letaba. This report stimulated the present study, the purpose of which is to ascertain which ant species are most numerous in citrus orchards ln the Eastern Cape Province; the reasons for these ants being able to occupy orchards; and, finally, their relationships. A survey of the Sundays River Valley and the Fish River Valley revealed that three species - Anoplolepis custodiens Smith, Anoplolepis steingroeveri Forel, and Pheidole megacephala Fabricius - were commonly found in citrus orchards in association with Soft Brown Scale insects. The territorial relationships of these ants were determined by plotting their distribution at intervals for over a year. It was found that this distribution could be correlated with seasonal climatic conditions, the effects of farming practices, brood rearing requirements and behavioural differences between the three species. The ant, A.steingroeveri, had not been previously studied, and since foraging is an integral part of territorial behaviour, some aspects of its biology, and more especially its foraging activity, were investigated to compare it with the known biology of the other two species. Observations on the foraging activity of A. steingroeveri were made at monthly lntervals for almost a year, and correlated with climatic conditions prevailing at the time. Some seasonal and dally variations in foraging behaviour could not be readily explained in terms of the effects of temperature and humidity on the ants. Other factors, includ1ng trophallactic stimulation and overcast skies, were found to influence ant activity. Owing to the apparent lack of information in the literature and possibility of periodic honeydew production by Soft Brown Scale insects controlling ant activity was investigated in the laboratory. The results of this study showed that it was not likely that honeydew excretion restricted the activity of the ants. Several investigators have also found that many interrelated climatic factors correlated with ant foraging behaviour, but have expressed dissatisfaction at not being able to reach the crux of the matter. To clarify the issue a constant temperature chamber was constructed in which a colony of Crematogaster ants was housed and the ants were subjected to a series of temperatures at different humidities, all other factors were eliminated or kept constant. The effects of these two factors on the thermokinetics and foraging activity of the ants were registered. This thesis contains several sections and at the end of each the results are discussed in the light of the available literature and comparisons are drawn between the species under investigation. The main results are given in the summary. After the summary two appendices are included. One is an attempt to compare the effect on ant size of the honeydew diet of orchard colonies with the proteinaceoue diet of veld ants. The other appendix is an experiment to control citrus ants with an insecticide.
- Full Text:
- Date Issued: 1957
The British organ and its music during the nineteenth century
- Authors: Wise, James Patrick Gerald
- Date: 1957
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2694 , http://hdl.handle.net/10962/d1013429
- Description: It is a curious fact that, although the literature of the organ is a reasonably large one, no attempt has been made to study the history of the instrument in Britain in any detail. Hopkins and Rimbault covered a certain amount of ground up to 1800, but even they could not deal very extensively with the subject in a volume that was tracing the history of the organ not only in Britain, but throughout Europe, and not only its history but its construction also. For similar reasons Dr. Sumner? (name unclear), in his recent book, could paint little more than an outline picture. However, the British organ's development prior to 1800 was one that does not admit of very discursive treatment. Progress was lamentably slow in comparison with that of Continental organs; and consequently the nineteenth century dawned with British organ-building literally hundreds of years behind that of France, Germany, Belgium and Holland. Yet, a century later, the position was redeemed, and even before the present era opened, the products of British organ-builders were not merely equal to, but, in general superior to those of the Continent in tonal design, mechanism, in artistic finish, and in ordinary maintenance and preservation. The nineteenth century, then, must clearly be regarded as a remarkable, indeed glorious, period in British organ-building, in fact one is tempted to enquire, whether there exists, in the entire artistic and scientific history of any country a similar example of accelerated development; in which one country has made up three hundred years' leeway in one third of that time. This thesis therefore, sets out to examine and describe the events of the century, and the men who were responsible for those events, to trace the growth of the organ in its various departments, and as the instrument itself is only a means to an end, to say something about the way in which it was used, the music that was played on it, and the men who played and composed this music. The thesis is divided into two volumes, the first deals entirely with the history of the instrument and its builders during the nineteenth century, with an introduction briefly recounting the story from the Restoration up to the year 1800; and the second volume is concerned with the music and the musicians as well as the several detailed indexes which are so necessary if a work of this kind is to be of any value at all. A full bibliography is given in Volume Two, but supreme acknowledgement must be paid here to the quarterly periodical "The Organ" - still thriving after an active career that began in July 1921. Its scholarly articles range over the whole field of international organ-building and organ-history, and without its help this thesis would have been far less comprehensive in its scope and far lesss authorative in its source-material.
- Full Text:
- Date Issued: 1957
- Authors: Wise, James Patrick Gerald
- Date: 1957
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2694 , http://hdl.handle.net/10962/d1013429
- Description: It is a curious fact that, although the literature of the organ is a reasonably large one, no attempt has been made to study the history of the instrument in Britain in any detail. Hopkins and Rimbault covered a certain amount of ground up to 1800, but even they could not deal very extensively with the subject in a volume that was tracing the history of the organ not only in Britain, but throughout Europe, and not only its history but its construction also. For similar reasons Dr. Sumner? (name unclear), in his recent book, could paint little more than an outline picture. However, the British organ's development prior to 1800 was one that does not admit of very discursive treatment. Progress was lamentably slow in comparison with that of Continental organs; and consequently the nineteenth century dawned with British organ-building literally hundreds of years behind that of France, Germany, Belgium and Holland. Yet, a century later, the position was redeemed, and even before the present era opened, the products of British organ-builders were not merely equal to, but, in general superior to those of the Continent in tonal design, mechanism, in artistic finish, and in ordinary maintenance and preservation. The nineteenth century, then, must clearly be regarded as a remarkable, indeed glorious, period in British organ-building, in fact one is tempted to enquire, whether there exists, in the entire artistic and scientific history of any country a similar example of accelerated development; in which one country has made up three hundred years' leeway in one third of that time. This thesis therefore, sets out to examine and describe the events of the century, and the men who were responsible for those events, to trace the growth of the organ in its various departments, and as the instrument itself is only a means to an end, to say something about the way in which it was used, the music that was played on it, and the men who played and composed this music. The thesis is divided into two volumes, the first deals entirely with the history of the instrument and its builders during the nineteenth century, with an introduction briefly recounting the story from the Restoration up to the year 1800; and the second volume is concerned with the music and the musicians as well as the several detailed indexes which are so necessary if a work of this kind is to be of any value at all. A full bibliography is given in Volume Two, but supreme acknowledgement must be paid here to the quarterly periodical "The Organ" - still thriving after an active career that began in July 1921. Its scholarly articles range over the whole field of international organ-building and organ-history, and without its help this thesis would have been far less comprehensive in its scope and far lesss authorative in its source-material.
- Full Text:
- Date Issued: 1957
The morphology of the Weberian apparatus of Labeo umbratus Smith
- Authors: Dennis, Clive Roy
- Date: 1957
- Subjects: Fishes -- Anatomy -- South Africa , Weberian apparatus -- Morphology , Fishes -- South Africa -- Tyumie River , Eastern Cape (South Africa) -- Fishes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5907 , http://hdl.handle.net/10962/d1014766
- Description: In Labeo umbratus only the first three anterior vertebrae undergo any modification. These vertebrae are not completely anchylosed with each other and are closely associated with the four Weberian ossicles. Movement is however restricted between these vertebrae since this is essential for the efficient functioning of the Weberian ossicles. The first vertebra is well developed the absence of a spinous process and neural arch in the first vertebra may perhaps be explained by the findings of some workers who derive the claustrum from the former and the scaphium from the latter. A small muscle has its origin on the claustrum and its insertion in the angle formed by the dorsal and medial processes of the scaphium. A second muscle originates in the pit-like excavation of the first vertebra and is inserted on the ventral process of the scaphium. The intercalarium possesses horizontal, articular and ascending processes; a portion of the horizontal process being imbedded in the interossicular ligament. In Labeo umbratus it is unlikely that the intercalarium represents (if it does so at all) the entire neural arch of the second vertebra. From a morphological point of view it seems likely that the intercalarium may function as a lever. A transversely situated ductus endolymphaticus joins the two sacculi to each other. The sagitta, in the region of the ductus endolymphaticus has a long, lateral "wing-like" process which projects into the cavity of the sacculus. The sacculus anilagena are innervated by the n. saccularis and the n. lagenaris respectively. The ductus endolymphaticus is prolonged posteriorly into a median unpaired sinus endolymphaticus. Although the only serious objection to Weber's theory is the fact that there could be no differential action of the two ears, the basic idea seems valid. Sagemehl's theory cannot be accepted. It seems likely that the Weberian ossicles are necessary structures for audition and to the hydrostatia function of the air-bladder.
- Full Text:
- Date Issued: 1957
- Authors: Dennis, Clive Roy
- Date: 1957
- Subjects: Fishes -- Anatomy -- South Africa , Weberian apparatus -- Morphology , Fishes -- South Africa -- Tyumie River , Eastern Cape (South Africa) -- Fishes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5907 , http://hdl.handle.net/10962/d1014766
- Description: In Labeo umbratus only the first three anterior vertebrae undergo any modification. These vertebrae are not completely anchylosed with each other and are closely associated with the four Weberian ossicles. Movement is however restricted between these vertebrae since this is essential for the efficient functioning of the Weberian ossicles. The first vertebra is well developed the absence of a spinous process and neural arch in the first vertebra may perhaps be explained by the findings of some workers who derive the claustrum from the former and the scaphium from the latter. A small muscle has its origin on the claustrum and its insertion in the angle formed by the dorsal and medial processes of the scaphium. A second muscle originates in the pit-like excavation of the first vertebra and is inserted on the ventral process of the scaphium. The intercalarium possesses horizontal, articular and ascending processes; a portion of the horizontal process being imbedded in the interossicular ligament. In Labeo umbratus it is unlikely that the intercalarium represents (if it does so at all) the entire neural arch of the second vertebra. From a morphological point of view it seems likely that the intercalarium may function as a lever. A transversely situated ductus endolymphaticus joins the two sacculi to each other. The sagitta, in the region of the ductus endolymphaticus has a long, lateral "wing-like" process which projects into the cavity of the sacculus. The sacculus anilagena are innervated by the n. saccularis and the n. lagenaris respectively. The ductus endolymphaticus is prolonged posteriorly into a median unpaired sinus endolymphaticus. Although the only serious objection to Weber's theory is the fact that there could be no differential action of the two ears, the basic idea seems valid. Sagemehl's theory cannot be accepted. It seems likely that the Weberian ossicles are necessary structures for audition and to the hydrostatia function of the air-bladder.
- Full Text:
- Date Issued: 1957
The positive contribution of the religious life to the life of the church
- Authors: Clucas, Robert Stephen
- Date: 1957
- Subjects: Religion , Christian life , Anglicans
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1291 , http://hdl.handle.net/10962/d1014701
- Description: The positive contribution of the religious life to the life of the church as a whole. Chapter one: presuppositions of an Anglican, with particular views of ministry, Bible, church and sacraments. Presupposition as regards friendship acknowledgement of influence of C.S. Lewis. Prejudices from outside. The old prejudices, their causes and historical foundation. New prejudices in the present-day world. Chapter two. Misunderstandings from within. The religious life as a higher way of perfection. False view of detachment. Celibacy of the priesthood. Correctives to those misunderstandings. Chapter three. The temporal and the temporary. Contributions which religious life makes continually in a fallen world. The temporary contributions made at different times. Chapter four. The eternal and the inward. Eternal aspects of the threefold vow and of the worship of community life. Contribution of religious throughout the ages to ascetic and mystical theology, which builds on inner life of the Christian. Chapter five. Conclusions and speculations. Re-examination of definition of the religious life. Side developments of the religious life. Three protestant communities. The religious life and present-day problems.
- Full Text:
- Date Issued: 1957
- Authors: Clucas, Robert Stephen
- Date: 1957
- Subjects: Religion , Christian life , Anglicans
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1291 , http://hdl.handle.net/10962/d1014701
- Description: The positive contribution of the religious life to the life of the church as a whole. Chapter one: presuppositions of an Anglican, with particular views of ministry, Bible, church and sacraments. Presupposition as regards friendship acknowledgement of influence of C.S. Lewis. Prejudices from outside. The old prejudices, their causes and historical foundation. New prejudices in the present-day world. Chapter two. Misunderstandings from within. The religious life as a higher way of perfection. False view of detachment. Celibacy of the priesthood. Correctives to those misunderstandings. Chapter three. The temporal and the temporary. Contributions which religious life makes continually in a fallen world. The temporary contributions made at different times. Chapter four. The eternal and the inward. Eternal aspects of the threefold vow and of the worship of community life. Contribution of religious throughout the ages to ascetic and mystical theology, which builds on inner life of the Christian. Chapter five. Conclusions and speculations. Re-examination of definition of the religious life. Side developments of the religious life. Three protestant communities. The religious life and present-day problems.
- Full Text:
- Date Issued: 1957
The solubility of barium sulphate in water at 25°
- Authors: Rosseinsky, D R
- Date: 1957
- Subjects: Chemistry, Physical and theoretical , Solubility , Barium sulfate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4491 , http://hdl.handle.net/10962/d1013097
- Description: Barium sulphate is a widely used analytical precipitate and for this reason its properties have been extensively studied. The variety of results encountered with barium sulphate samples prepared by different methods is an indication of the complex nature of this interesting substance. Intro., p. 8.
- Full Text:
- Date Issued: 1957
- Authors: Rosseinsky, D R
- Date: 1957
- Subjects: Chemistry, Physical and theoretical , Solubility , Barium sulfate
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4491 , http://hdl.handle.net/10962/d1013097
- Description: Barium sulphate is a widely used analytical precipitate and for this reason its properties have been extensively studied. The variety of results encountered with barium sulphate samples prepared by different methods is an indication of the complex nature of this interesting substance. Intro., p. 8.
- Full Text:
- Date Issued: 1957
The struggle for national independence in its international setting : its economic and political background and its manifestation in the Fourth Committee of the United Nations General Assembly
- Authors: Lumsden, Geoffrey S
- Date: 1957
- Subjects: United Nations. General Assembly Self-determination, National Sovereignty Economics -- Political aspects Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1091 , http://hdl.handle.net/10962/d1012790
- Description: The decade following the close of the Second World War has been dominated throughout by the clash of political power of the United States and the Soviet Union. Their wartime alliance has crumbled. New, antagonistic alliances have come into existence. The so-called 'EastWest' split, polar in its effect, has forced the admission that prospects of stable peace depend on how successfully bridges can be made to span the gulf. This over-riding and pervading reality has blinded us to the importance of another struggle, which is everywhere mounting in force and intensity and which history may well record as a dominant theme of the twentieth century -- the world-wide struggle for independence. In some cases it has produced revolution and violence: full-scale wars have been fought in its cause in Indonesia and Indo-China; military engagements have taken place in Kenya and Tunisia; Cypriots and British garrison forces have exchanged fire; Malayans have rioted; and 'incidents' too numerous to detail have been reported from a great variety of countries where political dependence exists. Intro., p. 1.
- Full Text:
- Date Issued: 1957
- Authors: Lumsden, Geoffrey S
- Date: 1957
- Subjects: United Nations. General Assembly Self-determination, National Sovereignty Economics -- Political aspects Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1091 , http://hdl.handle.net/10962/d1012790
- Description: The decade following the close of the Second World War has been dominated throughout by the clash of political power of the United States and the Soviet Union. Their wartime alliance has crumbled. New, antagonistic alliances have come into existence. The so-called 'EastWest' split, polar in its effect, has forced the admission that prospects of stable peace depend on how successfully bridges can be made to span the gulf. This over-riding and pervading reality has blinded us to the importance of another struggle, which is everywhere mounting in force and intensity and which history may well record as a dominant theme of the twentieth century -- the world-wide struggle for independence. In some cases it has produced revolution and violence: full-scale wars have been fought in its cause in Indonesia and Indo-China; military engagements have taken place in Kenya and Tunisia; Cypriots and British garrison forces have exchanged fire; Malayans have rioted; and 'incidents' too numerous to detail have been reported from a great variety of countries where political dependence exists. Intro., p. 1.
- Full Text:
- Date Issued: 1957
Verkenninge in die woordeskat van die poësie met spesiale verwysing na N. P. van Wyk Louw
- Authors: De Villiers, Aart
- Date: 1957
- Subjects: Louw, N. P. van Wyk (Nicolaas Petrus van Wyk), 1906-1970 -- Criticism and interpretation , Afrikaans poetry -- History and criticism
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3644 , http://hdl.handle.net/10962/d1014742
- Description: [From Introduction]. Soos die titel aandui, wil hierdie skripsie bloot verkenninge wees. Dit sal vir die leser duidelik wees dat dieselfde metode van benadering wat ek hier op sekere aspekte van die woordeskat van van Wyk Louw se poësie toegepas het, ook op ander woordsoorte toegepas sou kan word, en ook op die werk van ander digters. As 'n mens die gegewens wat jy so verkry, histories sou beskou, sou jy 'n baie interessante kykie kry op die ontwikkeling van die woordeskat in die Afrikaanse poësie. ln die beste van een skripsie is so iets egter, soos duidelik sal blyk, nie moontlik nie. Later, voel ek, sou miskien met vrug op dié grondslag voortgebou kan word.
- Full Text:
- Date Issued: 1957
- Authors: De Villiers, Aart
- Date: 1957
- Subjects: Louw, N. P. van Wyk (Nicolaas Petrus van Wyk), 1906-1970 -- Criticism and interpretation , Afrikaans poetry -- History and criticism
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3644 , http://hdl.handle.net/10962/d1014742
- Description: [From Introduction]. Soos die titel aandui, wil hierdie skripsie bloot verkenninge wees. Dit sal vir die leser duidelik wees dat dieselfde metode van benadering wat ek hier op sekere aspekte van die woordeskat van van Wyk Louw se poësie toegepas het, ook op ander woordsoorte toegepas sou kan word, en ook op die werk van ander digters. As 'n mens die gegewens wat jy so verkry, histories sou beskou, sou jy 'n baie interessante kykie kry op die ontwikkeling van die woordeskat in die Afrikaanse poësie. ln die beste van een skripsie is so iets egter, soos duidelik sal blyk, nie moontlik nie. Later, voel ek, sou miskien met vrug op dié grondslag voortgebou kan word.
- Full Text:
- Date Issued: 1957
A critical study of the curcumin method for the determination of boron in plant material
- Authors: Davidson, R J
- Date: 1958
- Subjects: Plants -- Nutrition , Boron , Turmeric
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4458 , http://hdl.handle.net/10962/d1011003
- Description: Methods for the determination of boron are reviewed. A thorough investigation of the curcumin method was undertaken. Factors such as spectral absorption, boron volatilisation and the effects of pH, the stability of reagents and colour solutions, the drying of reaction products and the interference from certain elements, were investigated. A study of the efficiency of extracting boron from plant material using an ashing procedure is presented. The modified curcumin method for the determination of boron in plant material is described. The statistical accuracy and precision of the modified method is presented. The modified method was used to determine the boron content in citrus and pineapple leaf samples obtained from various parts of the Eastern Cape.
- Full Text:
- Date Issued: 1958
- Authors: Davidson, R J
- Date: 1958
- Subjects: Plants -- Nutrition , Boron , Turmeric
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4458 , http://hdl.handle.net/10962/d1011003
- Description: Methods for the determination of boron are reviewed. A thorough investigation of the curcumin method was undertaken. Factors such as spectral absorption, boron volatilisation and the effects of pH, the stability of reagents and colour solutions, the drying of reaction products and the interference from certain elements, were investigated. A study of the efficiency of extracting boron from plant material using an ashing procedure is presented. The modified curcumin method for the determination of boron in plant material is described. The statistical accuracy and precision of the modified method is presented. The modified method was used to determine the boron content in citrus and pineapple leaf samples obtained from various parts of the Eastern Cape.
- Full Text:
- Date Issued: 1958
A statistical study of the errors involved in the sampling and chemical analysis of soils and plants, with particular reference to citrus and pineapples
- Steyn, Willem Johannes Abraham
- Authors: Steyn, Willem Johannes Abraham
- Date: 1958
- Subjects: Soil chemistry , Plants -- Analysis , Soils -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4506 , http://hdl.handle.net/10962/d1013291
- Description: 1. Accurate and reproducible methods for the determination of N and acid- extractable P in soils are described. The variations in N, P, and K found by intensive sampling of three different soil types are presented. 3. Suggestions for the adequate sampling of soils for various purposes arc given. 4. A study is presented of the preparative stages in leaf analysis (washing, drying, grinding and storage) as applied to citrus and pineapple leaf material. Likely errors are pointed out and procedures whereby these may be minimised are described. 5. A reliable wet-ashing procedure for obtaining leaf solutions is described. 6. Accurate and reproducible methods for the determination of total N, P,. K, Ca, Mg, Na, Fe, Mn, Zn and Cu in citrus and pineapple leaves are presented. 7. It is shown that diurnal variations in nutrient concentrations occur in citrus and pineapple leaves. 8. The variations in N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu, occurring from tree to tree in 3 different Navel orange blocks are presented. It is shown that if all these elements are to be represented . to within 10% of the mean values on a 19 : 1 probability level, all the trees in the blocks would have to be sampled. Reasonable sampling procedures for various purposes are suggested. 9. The variations in N, P, K, Ca, Mg, Fe, Mn, Zn and Cu, occurring in 3 different Cayenne pineapple plantations are presented and described. Suitable sampling procedures are suggested.
- Full Text:
- Date Issued: 1958
- Authors: Steyn, Willem Johannes Abraham
- Date: 1958
- Subjects: Soil chemistry , Plants -- Analysis , Soils -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4506 , http://hdl.handle.net/10962/d1013291
- Description: 1. Accurate and reproducible methods for the determination of N and acid- extractable P in soils are described. The variations in N, P, and K found by intensive sampling of three different soil types are presented. 3. Suggestions for the adequate sampling of soils for various purposes arc given. 4. A study is presented of the preparative stages in leaf analysis (washing, drying, grinding and storage) as applied to citrus and pineapple leaf material. Likely errors are pointed out and procedures whereby these may be minimised are described. 5. A reliable wet-ashing procedure for obtaining leaf solutions is described. 6. Accurate and reproducible methods for the determination of total N, P,. K, Ca, Mg, Na, Fe, Mn, Zn and Cu in citrus and pineapple leaves are presented. 7. It is shown that diurnal variations in nutrient concentrations occur in citrus and pineapple leaves. 8. The variations in N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu, occurring from tree to tree in 3 different Navel orange blocks are presented. It is shown that if all these elements are to be represented . to within 10% of the mean values on a 19 : 1 probability level, all the trees in the blocks would have to be sampled. Reasonable sampling procedures for various purposes are suggested. 9. The variations in N, P, K, Ca, Mg, Fe, Mn, Zn and Cu, occurring in 3 different Cayenne pineapple plantations are presented and described. Suitable sampling procedures are suggested.
- Full Text:
- Date Issued: 1958
An investigation of isolated bursts of solar radio noise
- Shuter, William Leslie Hazlewood
- Authors: Shuter, William Leslie Hazlewood
- Date: 1958
- Subjects: Solar physics -- Research , Solar radio emission
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5539 , http://hdl.handle.net/10962/d1013216
- Description: The literature on isolated bursts and possible mechanisms of origin has been critically reviewed, and observations point to a mechanism involving omission of electromagnetc radiation from plasma oscillations in the solar corona excited by outward travelling disturbances. Solar noise observations on 125 Mc./s. recorded at Rhodes University during the period November 26 1957 - February 6 1958 have been analysed by the author for isolated bursts, and these observations show the same general features reported by previous investigators. In interpretation of these records particular attention has been devoted to two aspects of isolated bursts; namely the preponderance on single frequency records of double-humped bursts, and the shape of isolated burst profiles. The authors suggests that a probable explanation of double-humped bursts observed on any frequency f is that the first hump represents omission at or near the level of zero refractive index for f radiation, and that the second hump corresponds to harmonic omission at the f/2 level. Source velocities may be calculated from the time delay between the peaks and an average value of 2 x 10⁴ km./sec. was obtained from an analysis of 21 double-humped bursts. This value is in very good agreement with that deduced by Wild (1950b) from the rate of frequency drift of peak intensity of isolated bursts. Simple isolated bursts had decay profiles which are approximatley exponential in shape, and this is usually interpreted in terms of the natural decay of plasma oscillations in the medium of origin. The author has verified that the exponential function is a good fit to the observed decay profiles, but shows that a relation of the form I - ¹/n (superscript) ⋉ t (where I is intensity and t is time) fits just as well. An alternative model is suggested which would lead to an exponential-like decay profile which is not determined by the natural decay of plasma oscillations. The work concludes with some suggestions for further research.
- Full Text:
- Date Issued: 1958
- Authors: Shuter, William Leslie Hazlewood
- Date: 1958
- Subjects: Solar physics -- Research , Solar radio emission
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5539 , http://hdl.handle.net/10962/d1013216
- Description: The literature on isolated bursts and possible mechanisms of origin has been critically reviewed, and observations point to a mechanism involving omission of electromagnetc radiation from plasma oscillations in the solar corona excited by outward travelling disturbances. Solar noise observations on 125 Mc./s. recorded at Rhodes University during the period November 26 1957 - February 6 1958 have been analysed by the author for isolated bursts, and these observations show the same general features reported by previous investigators. In interpretation of these records particular attention has been devoted to two aspects of isolated bursts; namely the preponderance on single frequency records of double-humped bursts, and the shape of isolated burst profiles. The authors suggests that a probable explanation of double-humped bursts observed on any frequency f is that the first hump represents omission at or near the level of zero refractive index for f radiation, and that the second hump corresponds to harmonic omission at the f/2 level. Source velocities may be calculated from the time delay between the peaks and an average value of 2 x 10⁴ km./sec. was obtained from an analysis of 21 double-humped bursts. This value is in very good agreement with that deduced by Wild (1950b) from the rate of frequency drift of peak intensity of isolated bursts. Simple isolated bursts had decay profiles which are approximatley exponential in shape, and this is usually interpreted in terms of the natural decay of plasma oscillations in the medium of origin. The author has verified that the exponential function is a good fit to the observed decay profiles, but shows that a relation of the form I - ¹/n (superscript) ⋉ t (where I is intensity and t is time) fits just as well. An alternative model is suggested which would lead to an exponential-like decay profile which is not determined by the natural decay of plasma oscillations. The work concludes with some suggestions for further research.
- Full Text:
- Date Issued: 1958