Some comparative studies of the fauna in soils developed under natural forest, pine and bluegum
- Watts, John Christopher David
- Authors: Watts, John Christopher David
- Date: 1952
- Subjects: Soil science , Forest ecology , Soil animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5895 , http://hdl.handle.net/10962/d1013423
- Description: [From Introduction] It has been said that, "If a nation saves its trees, the trees will save the nation." The truth of this assertion is apparent in many parts of the world today. In South Africa, fires and demands in the past for timber have led to extensive depletion of the Natural Forests. In many cases, natural revegetation has been slow to develop and deterioration of the soil has resulted. The desire to replace the tree cover and at the same time to meet an increasing internal demand for timber, has led to widespread planting of Pine and Bluegum. It is probable that more trees have now been planted than were destroyed in the past. The silviculturist however, who develops a pure stand on land which previously supported the mixed stand, should anticipate a change in soil properties as a natural accompaniment of such an undertaking. The nature of this change is the primum mobile of the present comparative study. The forest soils studied were taken in the Cape Province in the following areas:- Grahamstown; Amatola Mountains, District Alice; Witte-els-Bosch, District Humansdorp, during the course of a year. The physical and chemical properties, and the faunal composition of the soil samples were examined in relation to the different tree covers. Because of the necessity of taking large numbers of samples and thorough examination of these to arrive at a definite conclusion, the work is necessarily incomplete. It is felt however that the results obtained justify a further study of this aspect of soil biology.
- Full Text:
- Authors: Watts, John Christopher David
- Date: 1952
- Subjects: Soil science , Forest ecology , Soil animals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5895 , http://hdl.handle.net/10962/d1013423
- Description: [From Introduction] It has been said that, "If a nation saves its trees, the trees will save the nation." The truth of this assertion is apparent in many parts of the world today. In South Africa, fires and demands in the past for timber have led to extensive depletion of the Natural Forests. In many cases, natural revegetation has been slow to develop and deterioration of the soil has resulted. The desire to replace the tree cover and at the same time to meet an increasing internal demand for timber, has led to widespread planting of Pine and Bluegum. It is probable that more trees have now been planted than were destroyed in the past. The silviculturist however, who develops a pure stand on land which previously supported the mixed stand, should anticipate a change in soil properties as a natural accompaniment of such an undertaking. The nature of this change is the primum mobile of the present comparative study. The forest soils studied were taken in the Cape Province in the following areas:- Grahamstown; Amatola Mountains, District Alice; Witte-els-Bosch, District Humansdorp, during the course of a year. The physical and chemical properties, and the faunal composition of the soil samples were examined in relation to the different tree covers. Because of the necessity of taking large numbers of samples and thorough examination of these to arrive at a definite conclusion, the work is necessarily incomplete. It is felt however that the results obtained justify a further study of this aspect of soil biology.
- Full Text:
The distribution, importance and biology of the important cotton pests of Moc̦ambique
- Da Silva Barbosa, António Jorge
- Authors: Da Silva Barbosa, António Jorge
- Date: 1952
- Subjects: Cotton -- Diseases and pests -- Moc̦ambique
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5844 , http://hdl.handle.net/10962/d1010977 , Cotton -- Diseases and pests -- Moc̦ambique
- Description: Up to the second half of the eighteenth century the most important fibres in the world were wool, flax and silk. But the Industrial Revolution in England, together with the invention of the Cotton gin by Whitney in 1793, soon gave cotton the first place amongst all the important fibers in world's textile industry. Although some attempts were made, both in Angola and Mozambique to cultivate cotton since remote days -- as far back as the American Civil War, when market prices suffered an important rise no serious efforts were made to grow this crop before the proclamation of the Portuguese Republic in 1910, when some definite legislation was passed to encourage the development of this culture.
- Full Text:
- Authors: Da Silva Barbosa, António Jorge
- Date: 1952
- Subjects: Cotton -- Diseases and pests -- Moc̦ambique
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5844 , http://hdl.handle.net/10962/d1010977 , Cotton -- Diseases and pests -- Moc̦ambique
- Description: Up to the second half of the eighteenth century the most important fibres in the world were wool, flax and silk. But the Industrial Revolution in England, together with the invention of the Cotton gin by Whitney in 1793, soon gave cotton the first place amongst all the important fibers in world's textile industry. Although some attempts were made, both in Angola and Mozambique to cultivate cotton since remote days -- as far back as the American Civil War, when market prices suffered an important rise no serious efforts were made to grow this crop before the proclamation of the Portuguese Republic in 1910, when some definite legislation was passed to encourage the development of this culture.
- Full Text:
A study of the comparative anatomy of the lateral compound eyes of arthropods
- Authors: Glaholm, J
- Date: 1947
- Subjects: Arthropoda -- Anatomy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5908 , http://hdl.handle.net/10962/d1014966
- Description: In this thesis the interest has centered mainly on the comparative anatomy of the lateral eyes of Arthropods especially the compound eyes, with some particular reference to those of Chilopoda. The comparative anatomy of the eyes of Chilopoda seemed to be of interest, since they possess in most cases simple lateral eyes, which are not characteristic of the adults of any other group of Arthropoda, except Arachnids, to which the Chilopoda are only remotely related In a few cases - in the Scutigeridae - "compound" eyes are present, which are very unusual in their internal anatomy. The following possibilities with regard to the relationships of the Chilopod eyes present themselves. The simple eyes may be the products of degeneration of a compound eye. Alternatively they may be ocelli of a very primitive pre-compound eye type, persisting where in some cases a compound eye has failed to develop. As a third possibility they may have been separately evolved in forms, in which the compound eye was lost or failed to develop. In the last case they would appear to be unrelated to those of any other Arthropods, except possibly those of Diplopods, to which they are very similar in structure. The "compound" eyes may be or the same type as the compound eyes in the remaining Arthropods, with the differences due to degeneration, or to specialisation. Alternatively they may be of a separate type and formed secondarily, either as a single new structure. or a coalescence of ocelli. The enquiry into the interrelationship of these eyes and their relation to the eyes of other Arthropoda raises several points for investigation. For the compound eyes it is necessary to decide whether they were primarily present in the ancestors of some or all of the classes or Arthropods, and whether they have a common or more or less diverse origin with some evolutionary convergence. For the lateral simple eyes it is necessary to decide whether there are any indications in phylogeny, ontogeny or anatomy of the primitive or secondary formation of a compound eye by the aggregation of numerous ocelli or the elaboration of one or these. Such information might be expected to throw light on the origin of the Scutigerid eye. Alternatively any indications of the formation of simple from compound eyes might show whether the Chilopod simple eyes could have evolved in this way from a Scutigerid or some other compound eye. Median eyes are present in some Trilobites, Eurypterida, Crustacea, Hexapods and Arachnida. Although they exhibit considerable variations in structure, they are all clearly simple eyes. As they are absent in Chilopoda and in the remaining Arthropods are entirely separate in origin from the lateral eyes, with a separate seat of innervation, their comparative anatomy is of little interest in this case. The main portion of the thesis deals with the comparative anatomy, origins and relationships of the different types of compound lateral eyes. The second part comprises a short appendix dealing with similar aspects of the lateral ocelli. Detailed descriptions and figures have been given for the eyes of eight species. Some mention is also made of points observed in the internal or external anatomy of species which were studied in less detail. The theoretical conclusions are based on material from the available literature and from these descriptions.
- Full Text:
- Authors: Glaholm, J
- Date: 1947
- Subjects: Arthropoda -- Anatomy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5908 , http://hdl.handle.net/10962/d1014966
- Description: In this thesis the interest has centered mainly on the comparative anatomy of the lateral eyes of Arthropods especially the compound eyes, with some particular reference to those of Chilopoda. The comparative anatomy of the eyes of Chilopoda seemed to be of interest, since they possess in most cases simple lateral eyes, which are not characteristic of the adults of any other group of Arthropoda, except Arachnids, to which the Chilopoda are only remotely related In a few cases - in the Scutigeridae - "compound" eyes are present, which are very unusual in their internal anatomy. The following possibilities with regard to the relationships of the Chilopod eyes present themselves. The simple eyes may be the products of degeneration of a compound eye. Alternatively they may be ocelli of a very primitive pre-compound eye type, persisting where in some cases a compound eye has failed to develop. As a third possibility they may have been separately evolved in forms, in which the compound eye was lost or failed to develop. In the last case they would appear to be unrelated to those of any other Arthropods, except possibly those of Diplopods, to which they are very similar in structure. The "compound" eyes may be or the same type as the compound eyes in the remaining Arthropods, with the differences due to degeneration, or to specialisation. Alternatively they may be of a separate type and formed secondarily, either as a single new structure. or a coalescence of ocelli. The enquiry into the interrelationship of these eyes and their relation to the eyes of other Arthropoda raises several points for investigation. For the compound eyes it is necessary to decide whether they were primarily present in the ancestors of some or all of the classes or Arthropods, and whether they have a common or more or less diverse origin with some evolutionary convergence. For the lateral simple eyes it is necessary to decide whether there are any indications in phylogeny, ontogeny or anatomy of the primitive or secondary formation of a compound eye by the aggregation of numerous ocelli or the elaboration of one or these. Such information might be expected to throw light on the origin of the Scutigerid eye. Alternatively any indications of the formation of simple from compound eyes might show whether the Chilopod simple eyes could have evolved in this way from a Scutigerid or some other compound eye. Median eyes are present in some Trilobites, Eurypterida, Crustacea, Hexapods and Arachnida. Although they exhibit considerable variations in structure, they are all clearly simple eyes. As they are absent in Chilopoda and in the remaining Arthropods are entirely separate in origin from the lateral eyes, with a separate seat of innervation, their comparative anatomy is of little interest in this case. The main portion of the thesis deals with the comparative anatomy, origins and relationships of the different types of compound lateral eyes. The second part comprises a short appendix dealing with similar aspects of the lateral ocelli. Detailed descriptions and figures have been given for the eyes of eight species. Some mention is also made of points observed in the internal or external anatomy of species which were studied in less detail. The theoretical conclusions are based on material from the available literature and from these descriptions.
- Full Text:
Argyroploce Leucotreta: “The false Codlin moth”
- Authors: Horne, H M R
- Date: 1939
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193375 , vital:45326
- Description: This introduction and ensuing essay are something in the nature of a personal confession. Deemed as such what I have written concerning Samuel Palmer has not, in any way, been written as an exercise, but rather for the purpose of self-edification. This I will elaborate upon while disclosing my motive for writing on Palmer. Palmer's works - when I first saw them - were something of a revelation. They seemed the alpha and omega of my own artistic endeavour. Perhaps the term which best describes the euphoria I felt is 1deja vu1, because although it describes a connectedness of sorts, the words have in their sound an exotic ring. There is in it an implied equivocation - and equivocality best describes my understanding of Samuel Palmer at that juncture. This euphoria I felt dimmed with the realisation that by purportedly claiming, as I was, Samuel Palmer's visionary landscapes as my goal I was treading on sacred ground; I'd arrived, as it were, in another's Paradise. The effects of this upon my own creativity were completely negative. Worse still, I lacked the necessary means to extricate myself from Palmer's paradisiacal visions. His influence was incapacitating and convoluting my own growth. It was obvious then that I had to be rid of Samuel Palmer. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 1939
- Full Text:
- Authors: Horne, H M R
- Date: 1939
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193375 , vital:45326
- Description: This introduction and ensuing essay are something in the nature of a personal confession. Deemed as such what I have written concerning Samuel Palmer has not, in any way, been written as an exercise, but rather for the purpose of self-edification. This I will elaborate upon while disclosing my motive for writing on Palmer. Palmer's works - when I first saw them - were something of a revelation. They seemed the alpha and omega of my own artistic endeavour. Perhaps the term which best describes the euphoria I felt is 1deja vu1, because although it describes a connectedness of sorts, the words have in their sound an exotic ring. There is in it an implied equivocation - and equivocality best describes my understanding of Samuel Palmer at that juncture. This euphoria I felt dimmed with the realisation that by purportedly claiming, as I was, Samuel Palmer's visionary landscapes as my goal I was treading on sacred ground; I'd arrived, as it were, in another's Paradise. The effects of this upon my own creativity were completely negative. Worse still, I lacked the necessary means to extricate myself from Palmer's paradisiacal visions. His influence was incapacitating and convoluting my own growth. It was obvious then that I had to be rid of Samuel Palmer. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 1939
- Full Text: