This study evaluated the diversity of the genus Eurydice on sandy beaches in South Africa by analysis of morphological as well as genetic data. Type specimens of the three Eurydice species currently known from South Africa, E. longicornis, E. kensleyi and E. barnardi were obtained from the Museum für Naturkunde in Berlin and the Iziko Museum in Cape Town, South Africa. These specimens were studied in order to become familiar with their morphology. Eurydice individuals obtained from 30 sites spanning the South African coast, from Port Nolloth on the north-west coast to Bhanga Nek on the north-east coast were then examined. The two species E. kensleyi and E. barnardi, as well as four new morphospecies (A, B, C and D) were discriminated from these individuals by suites of morphological character types. Morphospecies A, B, C and D were therefore delimited according to the Phenetic Species Concept. None of the Eurydice individuals examined exhibited the same suite of characters as E. longicornis. Molecular sequences of two mitochondrial markers, cytochrome c oxidase 1 and 16S rRNA were analysed using both distance- and monophyly based methods. Uncorrected p-distances, a Minimum Spanning Haplotype Network and Maximum Likelihood phylogenetic trees were investigated to determine genetic diversity and phylogenetic relationships in the six Eurydice morphospecies. Results from the genetic analysis made it possible to delimit morphospecies A B, C and D as phylospecies A, B, C and D according to the Phylogenetic Species Concept, thereby validating the species status of four new Eurydice species, provisionally called Eurydice A, Eurydice B, Eurydice C and Eurydice D. This increases the total number of Eurydice species from South Africa to seven, of which six form part of the macrofauna of sandy beaches. The outcomes of this study represent an important step in the resolution of the taxonomy of the genus Eurydice in South Africa and enhance current knowledge of the biodiversity of sandy beach macrofauna, thus facilitating better-informed decisions on conservation policies and management to the benefit of conservation of biodiversity on sandy beaches in South Africa.

The present work Is concerned with two aspects: I. A description is given of the distribution of mitoses in the inner enamel epithelium of the mouse molar teeth during ontogeny, from the aspect of the establishment of the crown pattern. This distribution is correlated with cusp formation. Within limits of experimental error during reconstruction and plotting the mitoses, it has been shown that mitosis ceases at an early stage in areas which will eventually lie at the cusp tips, but continues between them, so that the valleys grow downwards leaving the cusps in a more elevated position. In other words, the relative positions of the cusps (mitoses-free areas), and the valleys (areas of intense mitoses) on the crown have been shown to be mapped out (predetermined) early in development. The theory of 'insinuation' of the stratum intermedium among the inner enamel epithelium has been rejected. II. A description of the cytology of the ameloblasts andodontoblasts is given with the aim of adding more detail to earlier accounts. In particular, it is shown that the Golgi apparatus changes polarity and varies in form during the life cycle of the ameloblasts, and an attempt is made toarrive at a more concrete idea of its role during the life of ameloblasts. The Aoyama method is used for the first time for demonstrating the Golgi apparatus in teeth. Also, Powers' method for nerve fibres, is used for the first time to show the Golgi apparatus, a method which has not been used for this purpose in teeth or any other tissue. The cytologic activity of the formative cells has been correlated with the morphologic changes of the Golgi apparatus. This correlation has been used to illustrate important phases of amelogenesis and dentinogenesis. The presence of the kionoblasts" among the ameloblasts and the 'radial cells' among the odontoblasts is denied.

Many methods of age determination have been devised for use on large mammals. An attempt was made to discover whether they were applicable to a small species, how accurate the methods could be and whether the age determination criteria were influenced by environmental factors. This study was based on 199 known-age specimens of the mainland bank vole, Clethrionomys glareolus britannicus (Miller), and 169 specimens of the Skomer vole, C. g. skomerensis (Barrett-Hamilton).These two laboratory raised samples were used to assess the relative accuracy and reliability of different age determination criteria. Morphological characters which were used for ageing included: body weight, body measurements, skull measurements, molar root development, tooth wear, fusion of epiphyses, baculum, pelage, and dry weight of the eye lenses. Changes in these characters were studied through 18 months of age. Laboratory study showed that the dry weight of the eye lens gave the best results for ageing. Development of the molar roots found to be highly correlated with age, as was tooth wear. Fusion of ten sets of epiphyses combine to give a high degree of accuracy in age-determination up to the age of 14 months. The correlation of skull measurements, moult, body measurements, and body weight with age was also studied. Tables were prepared for estimating the age of the two subspecies from every character used and 95% confidence limits were attached to the results. A low-calcium diet was given to 60 known-age mainland bank voles hut there was no measurable effect even on homes and teeth. Seventy three known-age mainland hank voles were released in outdoor enclosures. Growth data of 18 of them were analysed and compared with data from laboratory-raised animals. The results were in agreement with the latter, except in regard to tooth wear and to some extent in root growth.

In this study of morphogenesis in D. uninucleata, growth was followed on semi-solid and liquid media. The ellipsoid ascospores germinated to form a branched septate mycelium, which is fragmented in shake culture. Sexual reproduction began when the sprout had 4-5 cells. The first ascus was initiated by the formation of isogametxvia between the sprout mother cell and the distal adjacent cell, these fused at their tips and formed an ascus. The ascus grew in size and formed multispored uninucleate ascospores on maturation. The pattern of ascus insertion in the sprout was predictable. Each ascus at initiation was 2 cells away from the adjacent proximal ascus and 3--5 cells behind the distal hyphal tip. Ascus insertion was governed by the metabolic level in the cells. The external nutrient gradient was not involved as the pattern was the same in the batch culture and in cultures on semi-solid media. The ascus unit is supported by 2 cells. The proximal poles of the sprout cells are more active in forming gametangia than the distal poles. 40-60% of the attempts to form asci fail due to only single gametangia being produced or two gametangia failing to fuse. A thick capsule was formed during the swelling phase of ascospore germination. It consists of microfibrils embedded in an amorphous matrix. In a search for morphological mutants no capsuleless mutant was found after treatment with UV or NTG. One sterile mutant was isolated with larger cells and larger nuclei than the wild type and was possibly a polyploid. Attempts to improve the synchrony of germinating ascospores and growing cells using hydroxyurea were unsuccessful. Using different carbon sources and different levels, vegetative growth and sexual reproduction were equally affected, irrespective of the rate of growth. Sprouts reproduced normally on reaching the 4-5 cell stage. Inhibitors of nucleic acid, protein synthesis, TGA cycle and metal chelating agents were added to the cultures at different stages of growth and showed that inhibition of growth could be achieved but at concentrations much higher than was shown in other fungi. If vegetative growth was inhibited ascus formation was equally inhibited. Exogenous cAMP increased the percentage of successful attempts to produce asci and decreased the time required for the culture to reach maturity. High temperature of 35°C increased the percentage of gametangial fusion failure and had no effect on other steps of ascus formation or the vegetative growth.

The functioning of the molar teeth depends upon a correct relationship between the cusps of the two jaws. This is perhaps less evident in man owing to the flatness of the molar crowns; accordingly, an animal with pointed, interlocking cusps was studied - the insectivous bat Hipposideros beatus. The purpose of the work was to find the growth processes involved to ensure a correct mutual positioning of the erupted teeth in an animal where normal occlusion is essential. So that with a knowledge of normal occlusion, factors causing malocclusion may be better understood. Graphic and wax-plate reconstructions were made of the teeth and jaws in a series of H. beatus embryos. The methods of reconstructing this difficult material are described in Chapter II. In Chapter III the adult dentition and the occlusal relations of the teeth are described. The latter aided by a slow-motion cinematograph study of the chewing action in a British bat. Chapter IV is concerned with the growth and calcification of the tooth germs. Chapter V is concerned with the movements of the tooth germs during ontogeny. In both these chapters the growth of the upper toothrow is compared with the growth of the lower toothrow. It is found that the intrinsic growth of the tooth germs is such, that at all stages, models of teeth, that will later occlude, will fit if put together. However the teeth do not occupy their correct positions relative to each other until eruption. To attain these positions complicated growth movements take place. These movements, and a possible explanation for them are described. Eruption appears to be the terminal phase of these growth movements. The results of the investigation are discussed in Chapter VI.

The taxonomy of the British Chloropidae is reviewed with special reference to the male post abdomen. A new secondary sexual character, the femoral comb, is found to occur in Oscinellinae. The male genitalia of each species are described and illustrated and the limits and division of genera into species groups are considered. Material collected during this study is considered together with existing material in museum and private collections and in order to stabilize the nomenclature available type specimens have been examined and interpreted. The known distribution and phenology of British species are recorded. The relationships of British Chloropidae are discussed at the interspecific and intergeneric level with reference to the world fauna. Several species are apparently undescribed and a number of species have not been recorded from Britain. The male genitalia are discussed in relation to existing generic concepts, and certain anomalies in the British genera are pointed out. The data in this thesis is related to the subfamily classification of Chloropidae, the systematic position of Chloropidae in the Diptera Cyclorrhapha and the theories of systematics in general.

During their 473 million-year diversification, gnathostomes came to exploit an unprecedented variety of trophic niches. Modifications to dental form and mineralized tissue constituents (i.e. enamel, dentines and in a few taxa, cementum) facilitated their exploitation of novel prey and/or plant matter. In general, it has been assumed that the intra-tissue level biomechanics of these constituents had little bearing on whole-tooth functionality, aside from enamel in mammals showing dental occlusion. Specifically, many mammals possess teeth that self-wear to functionality and show a diversity of derived dental tissues (e.g. prismatic enamel fabrics, coronal cementum) – some which have been shown to possess unique biomechanical attributes to resist wear and fracture. Here I formally test the hypothesis that the primitive gnathostome hard tissue material properties remained static prior to the cladogenesis of Mammalia. An ancillary goal is to glean initial insights on how the material properties of these dental tissues in non-mammalian and mammalian taxa may contribute to whole-tooth form, function, performance and diets. Properties were tested and examined using two standardized material science techniques, microindentation and nanoindentation, as well as a novel technique for quantifying fracture propagation from cracks formed during microindentation. The results from this investigation suggest these material properties are highly variable among gnathostome dentitions. Aside from hardness, there is not a significant relationship between most material properties and diet aside from enamel hardness. There are also complex fracture patterns seen in the enamels of mammals and chondrichthyans, showing that gnathostome lineages independently evolved properties to control fracture and damage done to tooth enamel. Overall, this study suggests that in the case of enamel hardness, natural selection operated at the tissue level to bring about shifts in tooth functionality throughout the gnathostome radiation. More material properties (i.e. fracture toughness) need to be investigated to uncover the true functional import of material properties in dental tissues and establish how the tissue complexes contributed to whole tooth function. / A Thesis submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Master of Science. / Summer Semester 2017. / August 1, 2017. / biomaterials, material properties, nanoindentation, teeth / Includes bibliographical references. / Gregory M. Erickson, Professor Directing Thesis; Steven Lenhert, Committee Member; William S. Oates, Committee Member; Scott J. Steppan, Committee Member.

No description available.

Prosodic /template Morphology, that "draws heavily on the theoretical apparatus and formalisms of the generative phonology model known as autosegmental phonology" (Katamba, F. 1993: 154), is the best analysis that can handle Arabic morphology. Verbs in Arabic are represented on three independent tiers: root tier, the skeletal tier and the vocalic melody tier (Katamba, F. 1993). Vowel morphemes, which are represented by diacritics, are inserted within the consonant morphemes, which are represented by primary symbols, to form words. The morpheme tier hypothesis paves the way to understand the nonconcatenative Arabic morphology. This paper analyzes gender in perfect active and passive 3rd person singular verbs on the basis of PM. The focus of the analysis shall be drawn heavily on the most common Arabic verbs; triconsonantal verbs, with brief introduction of the less common verbs; quadriconsonantal perfect active and passive masculine and feminine 3rd person singular verbs. I shall, too, cast the light on some vowel changes that some verbs undergo when voice changes.

Thesis (Ph. D.)--Universiteit van Amsterdam, 1909. / Includes bibliographical references.