bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abdominal appendages in the female and copula tory appendages in the male Asellus
Authors: Needham A. E. 
Published: April 2021

ABSTRACT
1. In the female Asellus aquaticus it is the first pair of pleopods which is missing and not the second pair, as was usually held. This condition is the result of an inhibition on the development of the last thoracic and first abdominal segments in later brood-pouch stages, an inhibition which is only temporary in the last thoracic segment and in the first abdominal segment of the male.
2. The resemblance between the second abdominal appendages in the female and the first pair of the male is therefore purely convergent.
3. The strong probability that the same condition holds throughout the sub- order Asellota is supported by a comparison of adult morphology, and should be verified by embryological study. It is more usual in Crustacea for appendages to be lost at the end than in the middle of a series.
4. The structure of the copulatory apparatus of the adult male Asellus is extremely complex, and apparently closely adapted to its mode of function. In contrast the female apparatus is of the simplest.
5. Points of evolutionary and genetical interest are raised by the condition of these appendages in the two sexes.
Spolia Bermudiana II. The Ciliary Feeding Mechanism of Tornaria
Authors: Garstang Walter 
Published: April 2021

ABSTRACT
During my first visit to Bermuda in February 1935, large Tornaria and Auricularia frequently occurred in the plankton, so that I hoped, in the intervals of other work, to be able to compare the feeding processes in the two types. For some unknown reason, however, ciliary action had always stopped in the large Auricularia nudibranchiata when examined in the laboratory, while Tornaria, on the other hand, was usually fresh and lively, and I made a preliminary study of its behaviour. On my second visit in June-July of this year (1938) both types were scarce, and I could make no further progress with the problem. It seems desirable, therefore, to publish my notes on the feeding of Tornaria, without waiting longer for the opportunity of a comparative study.
The Structure of the Ovary and the formation of the Corpus Luteum in Hoplodactylus Maculatus, Gray.
Authors: Boyd Mary M. M. 
Published: April 2021

ABSTRACT
The structure of the ovary, including stages in the ripening of the oocytes, is described. A prolonged diplotene stage with ‘lamp-brush ‘chromosomes is shown to occur in reptiles, as in other classes of vertebrates with large yolky eggs.
The striated layer of the egg membrane is shown to be composed of the same cuticular substance as the zona pellucida. A follicular epithelium composed of three types of cells, later reduced to a single layer of small cells, agreeing with Loyez’s observations, is described.
A discontinuous theca interna, comparable with that of mammalia, is noted outside the membrana propria of the nearly ripe oocyte.
A thin, soft, fibrous shell membrane is formed round the uterine egg and polyspermy occurs. The latebra, and the male and female pronuclei in apposition, are described.
The corpus luteum is shown to consist of luteal cells invested by fibroblasts from the theca externa. Septa of fibroblasts arb also present, but no blood-vessels. The theca is rich in capillaries. The theca interna plays no part in the development of the corpus luteum. A lipoid secretion, which may be of physiological importance, is formed in it. It is compared with that in Monotremes and Marsupials.
The Significance of ‘Chromatic Droplets’ in the Growth of Insects
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
From a review of the literature, and from observations on Rhodnius prolixus, it is concluded that the ‘chromatic droplets’ which appear in the epidermis during the moulting and metamorphosis of insects are formed from the dissolution of entire nuclei; nuclei that have become superfluous, either because they belong to specialized larval structures that are being discarded, or because the exuberance of cell division has led to their production in greater numbers than are needed.
Primary Sex-Phases in Ostrea edulis.
Authors: A. Cole H. 
Published: April 2021

ABSTRACT
1. It is only under the most favourable conditions that oysters (Ostrea edulis) mature in the first sexual phase in the same season as that in which they attach themselves. During this initial phase the oyster functions as a male.
2. Normally the first male phase is experienced on British beds in the summer following that in which the oyster attaches itself and is rapidly followed by the first female phase, the oocytes developing on the walls of the follicles while spermatogenesis proceeds in the lumina.
3. In favourable seasons about a third of a population of one-year-old oysters will spawn as females. In unfavourable years only a few of the heaviest oysters spawn. Following female spawning the second male phase is rapidly assumed.
4. The second male phase is followed by the second female phase, the oocytes developing while spermatogenesis is in progress. Emission of sperm may be continued up to within a few days of egg-spawning. If a male phase is reached towards the close of the season it is followed by a resting phase, without spermatogenesis or large oocytes in the gonad, which persists throughout the winter. Similar resting phases may occur during the summer if environmental conditions are unfavourable.
5. Every two-year-old oyster functions as a female in a favourable season, and thereafter under normal conditions passes through at least two sex-phases each season, functioning both as a male and as a female. Evidence is adduced to show that in populations of adult oysters on British beds 100 per cent, female functioning occurs in favourable seasons.
6. Gonad development is arrested from approximately the end of October until the beginning of April while the water temperature is below about 10° C. Oysters may winter in almost any sex-phase, but spermatogenesis does not occur, although ripe sperm morulae may be carried over from one season to the next. Egg development is arrested during the winter months.
7. Oysters which winter in a transitional phase between a male and a female phase may mature as pure females early in the following summer without any recrudescence of spermatogenesis. There is at this time, therefore, a high proportion of ripe females in the population.
8. Oysters which winter in a dormant male condition mature as good males early in the following season and spawn as females later in the summer. Female spawners may therefore be divided roughly into two groups—early and late spawners—and individual oysters tend to remain in the same group in successive years.
9. Breakdown and absorption of large eggs by phagocytes has been found to occur occasionally during the winter, but the circumstances in which this takes place are not known.
Development of the Mesonephros in a Teleostean—Thynnichthys sandkhol
Authors: Moghe M. A. 
Published: April 2021

ABSTRACT
The development of the mesonephros in teleostean fishes has been the subject of investigation by a large number of workers. Among these may be mentioned Rosenberg (1875), Goette (1875), Fürbringer (1878), Nussbaum (1878), Emery (1882), Hoffmann (1886), Felix (1897), and more recently Maschkowzeff (1934).
Notes on Certain Fresh-Water Species of Diatomaceæ
Authors: Donkin A. S. 
Published: April 2021

ABSTRACT
The late Professor Smith, in referring to the genus Epi- themia in his ‘Synopsis of the British Diatomaceæ ‘(vol. i, p. 11), observes that “this genus, as its name implies, is characterised by the adherence of its frustules to Aigre of larger growth. This character is true of most of the species, and even where not strictly applicable, as in E. gibba and others, we detect a disposition to rely on a foreign body for support, their frustules being usually embedded in the mucus of some member of the family Palmellaceæ.” Recently I have had an opportunity of ascertaining that Epithemia gibba is strictly an adherent species, and that its supposed exceptional character in this respect has been based on insufficient observation.
The Cytology and Histochemistry of the Neurones of Periplaneta americana
Authors: ASHHURST DOREEN E. 
Published: April 2021

The only cytoplasmic inclusions visible in the neurones by the light microscope are the lipochondria and mitochondria. It is suggested that the Golgi bodies, seen in preparations made by the Golgi techniques, are produced by the deposition of osmium or silver on the surface of the lipochondria.
The lipochondria consist of phospholipids and cerebrosides. There is also some lipid in the cytoplasm, together with carbohydrates, proteins, and RNA.
Extrusion of nuclear material during oogenesis in Blatta orientalis
Authors: GRESSON R.A. R. , THREADGOLD L. T. 
Published: April 2021

ABSTRACT
That nucleolar material is extruded to the cytoplasm of the young oocyte of Blatta orientalis is confirmed by means of electron microscopy. The nucleolus and nucleolar extrusions are shown to contain RNA. In addition to the nucleolar extrusions, vesicle-like structures originate in the nuclear membrane and from there pass into the cytoplasm where they become indistinguishable from elements of the endoplasmic reticulum. When the nucleolar extrusions reach the cytoplasm they increase in size, come into close association with a few mitochondria, and migrate towards the periphery of the cell. It is concluded that the emission of material from the nucleolus and the passage of vesicles from the nuclear membrane to the cytoplasm are necessary prerequisites for the process of vitellogenesis.
The fine structure and biology of the egg-shell of the wheat bulb fly, Leptohylemyia coarctata
Authors: Hinton H. E. 
Published: April 2021

ABSTRACT
The egg-shell of Leptohylemyia coarctata consists of 3 meshwork layers. The outermost wall is a sheet with perforations that are usually 5 to 10 μ wide. Across each of these perforations is a very fine network, the interstices of which are 0·1 to 0·2 μ wide. The middle meshwork layer is 2 to 7 μ thick. It is chiefly responsible for the mechanical strength of the shell. The inner meshwork layer is usually 2 to 4 μ thick. It consists of vertical columns extending inwards from the middle layer. The apices of the columns are branched in a plane normal to their long axes. These horizontal branches anastomose to form an open network, which is the innermost wall of the shell. The struts of all meshworks consist of fibrils 1 to 1·5 mμ · in diameter. The fibrils form a meshwork, the interstices of which are usually 2 to 5 m μ · wide.
When the egg is submerged in water, a film of air is held by the hydrofuge inner meshwork. This film of air functions as a plastron, but as a relatively inefficient one because above it there is a stationary layer of water 8 to 15 · thick held by the 2 upper meshwork layers, which are hydrophil. Between the shell and the subchoral cuticle there is a waxy membrane. This membrane is closely attached to the inner face of the shell. It plays an important part in the resistance of the egg to desiccation.
Studies on Campodea (Diplura) : the anatomy of the glands and sense-organs of the head
Authors: George Martin 
Published: April 2021

ABSTRACT
Recent studies of the cephalic glands of Campodea have shown previous descriptions to be misleading in several respects. The campodeid salivary glands lie in the posterolateral parts of the head capsule and each is composed of a much-coiled ‘labyrinth’ and a distal end-sac. The histology of the two regions differs greatly, and although a little secretory activity has been observed in the end-sac, the labyrinth appears to be responsible for secreting most of the definitive saliva. The latter is passed to the outside down a median duct which opens between the ‘setigerous plates’ of the labium. Although the salivary glands of Campodea have homologues in other apterygote insects and the myriapods, the homology of the second pair of cephalic organs, the lobulate glands, is obscure. These glands, which are situated in the head and the anterior part of the prothorax, are composed of cells arranged around a system of ducts opening into the cephalic haemocoel. The ducts contain acidophil material which is secreted by the gland cells and numerous small cells which are perhaps haemocytes. The size of the lobulate glands relative to the size of the body increases as the animal matures, and it is possible that they are responsible for secreting some form of growth hormone. The cheek glands are situated beneath the epidermis of the lateral part of the head capsule and are composed of two different types of cells ; their homology and function are unknown. The paired lateral sense-organs also lie beneath the cephalic epidermis, but each is a bowl-shaped structure composed of numerous bifid sensory cells. The latter are innervated and each contains a bifid sensory rod. The distal prolongations of the sensory cells are interpolated between accessory cells whose cytoplasm contains granules. The latter may be either proximally or distally situated in the cell but are not composed of pigment. The definitive structure of these senseorgans is only attained in the sexually mature insect and they are only represented by disorganized groups of cells in the nymphs. Preliminary experiments are described which indicate that the lateral sense-organs are not concerned with the perception of optical stimuli and their function and similarities to other insect sense-organs are discussed.
Electron microscopy of the development of tracheoles in Drosophila melanogaster
Authors: Ahmad Shafiq S. 
Published: April 2021

ABSTRACT
The tracheoblasts associated with the flight-muscles of Drosophila were studied by electron microscopy. During the developmental stages the cytoplasm of such tracheoblasts shows extensive membrane structures arranged in whorls. It seems that these membranes become aligned in pairs, spread out in tracheoblast cytoplasm, and form the walls of the new tracheolar vessels. The membranous whorls appear to have no obvious relationship with the usual endoplasmic reticulum, Golgi apparatus or plasma membranes. They are probably produced from certain large granules distributed irregularly in the cytoplasm of the young tracheoblasts.
Membranes limiting the tracheoles from the tracheoblast cytoplasm (the so-called mestracheons) are not usually seen in the younger stages. They are sometimes seen after the cuticular lining of the tracheoles has been formed.
The histology and histochemistry of development and resorption in the terminal oocytes of the desert locust, Schistocerca gregaria
Authors: Lusis O. 
Published: April 2021

ABSTRACT
During vitellogenesis the follicular cells play an active part in the synthesis of yolk. The term ‘corpus luteum’ as applied to the ovary of the locust is invalid and two terms ‘white’ and ‘yellow* follicle have been introduced to describe the separate identities of the normal and pathological postovulatory follicle. The protein yolk is a protein- carbohydrate compound, presumably a glycoprotein. Three kinds of lipid bodies are present; the first is a phospholipid, the second a combined phospholipid and triglyceride, and the third triglyceride. Lipids are coloured by dissolved (β-carotene. Concentration or absorption of the lipids causes the crystallization of carotene and the formation of the pigment body. During resorption the follicular cells act as lecitholytic cells, first breaking down the protein and then the lipid yolk, and finally degenerating themselves. It is suggested that the oocytes have an inherent potential for resorption, the realization of which depends on various factors within the body.
Intranuclear lipids in the early oocytes of Heteropneustes fossilis (Teleostei)
Authors: Seshachar B. R. , Nayyar R. P. 
Published: April 2021

ABSTRACT
Purely lipid bodies have been encountered inside the nucleus of early oocytes of Heteropneustes fossilis. These are mixtures of phospholipids and triglycerides. They occur independently of the nucleoli. With the growth of oocyte they increase in size and number and move towards the nuclear membrane. During later stages they diffuse out into the cytoplasm presumably to take part in yolk formation.
A general method for silvering invertebrate central nervous systems
Authors: Fraser Rowell C. H. 
Published: April 2021

ABSTRACT
The best-known silvering methods are less successful with invertebrate than with vertebrate central nervous tissue. They fall into two classes with conflicting merits. In the first, metallic impregnation is assisted by accessory chemical agents, and subsequent development deposits only limited silver derived from the impregnating bath ; in the second, impregnation is in a simple silver nitrate solution, and the development is physical, the silver deriving from the developer. The most important part of the first process is impregnation, development adding relatively little; impregnation is comparatively slight in the second process, which relies much more on development.
If an impregnation of the first type is followed by physical development, the results have the advantages of both methods. The final picture is as good as that produced by the classic methods, and the reliability of the result greatly increased ; the method is successful with a variety of difficult invertebrate material. A method is described, using Blest’s modification of Holmes’s impregnator (class I) and Samuel’s physical developer (class II). The effects of temperature, pH, and duration of impregnation are described and related to the needs of different tissues. Increases in both temperature over the range 30° to 70° C and pH from 7·0 to 9·0 have similar and summating effects: increase in intensity of axon staining, increase in background staining, and decrease in fibre specificity.
Cytotaxonomy of ticks
Authors: Kahn J. 
Published: April 2021

ABSTRACT
The material studied consisted of laboratory-bred specimens of 2 species of Prostriata and 8 species of Metastriata.
Ixodes ricinus and I. hexagonus (Prostriata) have XX : XY sex-determining mechanisms with diploid complements of 28 and 26 acrocentric chromosomes respectively. All the species of Metastriata studied have XX:XO sex-determining mechanisms with diploid complements of 21 and 22 chromosomes in males and females respectively. Haemaphysalis leporis palustris is the only species with metacentric chromosomes. Hyalomma spp., Dermacentor andersoni and Haemaphysalis leporis palustris each have X-chromosomes larger than any of the autosomes, whereas Rhipicephalus sanguineus and R. secundus do not have conspicuously large X-chromosomes.
In all the species studied early male meiotic prophase is characterized by a period of growth similar to that of oocytes at first meiotic division. This nuclear growth of the primary spermatocyte is thought to have evolved together with the production of a large-sized spermatozoon.
The structure of the testes and their accessory glands in Ixodes differs significantly from that of the corresponding organs in Metastriata. Ixodes also differs from the other genera studied as regards the splitting of the integument during ecdysis. It is suggested that Ixodes should be given the status of a ‘family’.
Adaptation of certain histological techniques for in situ demonstration of the neuro-endocrine system of insects and other animals
Authors: Dogra G. S. , Tandan B. K. 
Published: April 2021

ABSTRACT
Three techniques for staining the secretory neurones in sections were applied directly to the whole brain and/or intact organs of the neuro-endocrine system of certain insects, and the whole brain of various invertebrates and vertebrates. After minor changes in the original procedures, in situ staining was achieved in those components of the neuro-endocrine system that are known to contain the neurosecretory material. With the Victoria blue staining technique, the secretory neurones, the neurosecretory pathway, and the storage-and-release organ were stained satisfactorily in all the experimental animals, in such a way that observations could be made in whole mounts or suitably dissected portions of the bulk-stained preparations. With the aldehyde-fuchsin and aldehyde-thionin staining techniques, the somata and the proximal portion of the axon of the neurones and the storage-and-release organ were usually stained satisfactorily enough for purposes of observation in the invertebrate material only. On sectioning the bulk-stained components of the neuroendocrine system and mounting the sections, the sites known to contain the neurosecretory material were revealed promptly. On comparing the information derived from mounts of the bulk-stained preparations with that derived from sections of similar preparations, and also with that derived from routine histological procedure, no difference was detected.
The fine structure produced in cells by primary fixatives 2. Potassium dichromate
Authors: Baker John R. 
Published: April 2021

ABSTRACT
The exocrine cells of the mouse pancreas were fixed in potassium dichromate solution, embedded in araldite or other suitable medium, and examined by electron microscopy.
Almost every part of these cells is seriously distorted or destroyed by this fixative. The ergastoplasm is generally unrecognizable, the mitochondria and zymogen granules are seldom visible, and no sign of the plasma membrane, microvilli, or Golgi apparatus is seen. The contents of the nucleus are profoundly rearranged. It is seen to contain a large, dark, irregularly shaped, finely granular object; the evidence suggests that this consists of coagulated histone. The sole constituent of the cell that is well fixed is the inner nuclear membrane.
The destructive properties of potassium dichromate are much mitigated when it is mixed in suitable proportions with osmium tetroxide or formaldehyde.
The fine structure of the secondary lamellae of the gills of Gadus pollachius
Authors: Hughes G. M. , Grimstone A. V. 
Published: April 2021

ABSTRACT
The structure of the leaf-like secondary lamellae, across which gaseous exchange takes place, is described on the basis of an electron-microscope study of sectioned material. The epithelial layers on the two sides of the secondary lamellae are separated by widely spaced pillar cells, of characteristic form. These have a central cell body with wide flanges at each end which spread out below the epithelia. The flanges of adjacent pillar cells meet and connect, delimiting an extensive blood space between the pillar cell bodies. Pillar cells contain abundant mitochondria and membranes, and their cytoplasmic matrix is largely occupied by finely fibrous material. They appear to be responsible for the formation of a thick, collagen-containing basement membrane which lies between them and the overlying epithelia. There are also columns of basement membrane material which run transversely across the secondary lamellae, set in deep infoldings in the surface of the pillar cell bodies. Pillar cells appear to combine the functions of fibroblasts and the endothelial cells of true capillaries. The epithelium forming the outer surface of the secondary lamellae is one or more cells thick and consists of cells with large nuclei and abundant mitochondria and cytoplasmic membranes. The water/blood pathway across which gaseous exchange takes place consists of the epithelium, basement membrane and pillar cell flange and has a total thickness of 1 to 3μ.
The Use of Cajuput Oil in Microscopy
Authors: Brug S. L. 
Published: April 2021

ABSTRACT
During the world war 1914-18 our stock of xylene (xylol) in Java ran low; moreover, the small quantity that was left changed into a thick syrupy fluid which was useless as a medium for mounting water-fixed preparations in balsam. Chemists told us that the xylene had polymerized. In text-books of microscopical technique cedar-wood oil is recommended as a substitute for xylene in some cases. However, this oil was still scarcer in Java than xylene; therefore we resolved to try another ethereal oil, namely, cajuput oil. Of this oil, a product of the Malay Archipelago, unlimited quantities were available. It soon, proved to be not only a good substitute for xylene, but in some cases superior to it.