bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Structure of the Otolith of the Hake
Authors: Hickling C. F. 
Published: April 2021

ABSTRACT
The otolith of the hake (Merlucius merluccius Linn.) is a compound structure, comprising an organic and an inorganic constituent. The organic constituent is the more complex in structure, and consists of concentric shells (appearing in sections of the otolith as lamellae) which have a reticulate structure, and are probably fibrous in nature. The concentric shells are separated at a fairly constant distance of about 2μ from one another, and are bound together by comparatively stout radial fibres. The inorganic constituent consists of needle-like crystals, about 40μ in maximum length, and less than lμ thick, which are secreted among the radial fibres, and pass normally through the concentric shells of the organic constituent from the centre of the otolith to the periphery. These crystals interlock to give the otolith its very solid structure. The concentric rings, apparent when the entire otolith is viewed lying on its side, and which, in some species of fish, are used for the assessment of age, are due to the varying thickness of the concentric shells, described in (2) above. These are, typically, grouped in such a way that there are alternating zones where thick and thin concentric shells (lamellae) predominate. Where thick lamellae predominate an effect of opacity is produced, where thin lamellae predominate, one of comparative translucency. The thick lamellae are of the order of l·5μat their thickest, the thin lamellae extremely tenuous. The cause of the ringed structure in the entire otolith is therefore due to the organic constituent, the inorganic constituent (crystals) having a supporting function only, in the otolith. Immermann’s hypothesis, that the rings are due to the structure of the inorganic constituent, being an optical effect produced by an internal reflection of the light, caused by a twisting of the crystals, is not accepted as applying to the otolith of the hake.
Studies on the Germ-cell Cycle of Cryptocotyle lingua Creplin: 1. Gametogenesis in the Adult
Authors: Cable Raymond Millard 
Published: April 2021

ABSTRACT
The chromosomes of Cryptocotyle lingua have been counted and their shapes and sizes determined from observations on somatic and germinal cell divisions. The differences in structure and staining reactions of the germinal cells in mature and immature worms are described. 8. Oogenesis and spermatogenesis have been followed from the primary germ-cells of the immature worm to the early cleavage stages. More evidence has been added to that indicating the nonexistence of the ‘Primärtypus’ of maturation postulated by Goldschmidt. Gametogenesis in Cryptocotyle has been compared with that in other species.
On the so-called ‘Olfactory Pores’ in the Honey-bee
Authors: Newton H. C. F. 
Published: April 2021

ABSTRACT
The structure of the campaniform sensillae occurring on the wing-bases of the adult worker bee is described. The essential features in their later developmental phases in the pupa have been followed. The observations described lend no support to those of Maclndoo, that the actual termination of the nerve-fibre is exposed to the outside air. The wing-base organs, as described by other workers in different insects, are discussed, with special reference to the identity of the cellular elements composing these structures. The paper concludes with a short discussion of the position of the sensory neuron and a brief review of the supposed function of the campaniform sensillae.
The Turnover of Melanin in Xenopus laevis treated with Phenylthiourea
Authors: Sims R. T. 
Published: April 2021

ABSTRACT
Four sets of experiments were performed in which developing Xenopus laevis were treated with o-i% phenylthiourea. The animals used in experiments 1 and 2 were taken from a single batch of eggs, those in experiment 3 from another batch of eggs, and those in experiment 4 from a third batch. A suitable control group of untreated tadpoles was arranged for each experiment. In experiment 1 gastrulae were reared in a solution of phenylthiourea, which inhibited melanogenesis. In experiment 2 tadpoles, which possessed melanophores containing melanin, were kept in a solution of phenylthiourea for 6 weeks. No turnover of melanin was detected in these animals. Experiment 3 was carried out on tail regenerates. It showed that melanogenesis is inhibited by phenylthiourea and that no turnover of melanin occurs during treatment with this drug. In experiment 4 animals which had almost completed metamorphosis showed no evidence of turnover of melanin when treated with phenylthiourea.
The arrest of development of the tadpoles and the histological changes in the thyroid glands which occurred during treatment were used as evidence that phenylthiourea reached the tissues of the experimental animals.
The Action of Diethylstilboestrol on the Prostatic Epithelium of the Mouse
Authors: Horning E. S. 
Published: April 2021

ABSTRACT
1. The cellular changes in the prostatic epithelium of an inbred strain of mice (R HI), following short periods of treatment with large doses of oestrogen, are described.
2. The Golgi apparatus in the cells of the prostatic epithelium affords a precise indication of the degree of stimulation induced by oestrogenic substances.
3. Specific morphological changes in the Golgi substance occur in the epithelium of the anterior lobe of the prostate after 8 days’ treatment. Similar changes, following longer periods of treatment, also occur in the dorsal and ventral lobes.
4. Withdrawal of oestrogenic stimulation after 20 days’ treatment with relatively large doses is followed by a return of the prostatic epithelium and the Golgi apparatus to their normal condition in 21 days.
The Cultivation of Adult Mammalian Skin Epithelium in vitro
Authors: Medawar P. B. 
Published: April 2021

ABSTRACT
The purpose of this paper is to describe a simple technique for the shortterm cultivation of adult mammalian skin epithelium in vitro. The conditions of cultivation are such as allow the rapid proliferation and migratory spread of skin epithelium while maintaining the characteristic functional activity and histological appearance of its cells.
The technique was devised to investigate the effect of iso-antibodies on cells. It requires little, if any, modification for use as an adjunct to routine biochemistry (e.g. in studying the influence of specific metabolic inhibitors on cell movement and division: cf. Medawar, 1947), or for submitting cells to the direct action of hormones. It has the disadvantage that the cultivated cells do not grow away from the explanted tissue into the culture medium, so that the direct microscopic study of living cells (an amenity to which, in conventional tissue culture, most others have been sacrificed) must be forgone. The tissue can, however, be studied in the transformed state in which it is most familiar to histologists: in stained sections.
The Accumulation of Carotenoids in the Golgi Apparatus of Neurones of Helix, Planorbis, and Limnaea
Authors: Cain A. J. 
Published: April 2021

ABSTRACT
Repetition of some of Thomas’s (1948) work on Helix neurones and its extension to neurones of Planorbis and Limnaea confirms his conclusions that the batonnettes shown by standard Golgi methods are mitochondria, and the Golgi apparatus is represented by spheroid complexes, scattered throughout the cell but tending to be concentrated in the axon hillock.
The spheroid complexes appear to consist of an externum, continuous or not, which contains phospholipine and possibly other lipoids, and an internum in which carotenoids are accumulated. This accumulation is greater in Limnaea and Planorbis than in Helix.
Observations on the Branchial Crown of the Serpulidae (Annelida, Polychaeta)
Authors: Hanson Jean 
Published: April 2021

ABSTRACT
This paper records various observations supplementing, and in some cases correcting previous accounts of the internal structure of the branchial crown in Pomatoceros triqueter, Serpula vermicularis, Hydroides norvegica, Vermiliopsis infundibulum, Salmacina incrustans, Protula intestinum, Spirorbis corrugatus, and Spirorbis militaris. The muscles in the opercular peduncle of Pomatoceros are longitudinal. A single layer of small longitudinal muscle-fibres, of unknown function, has been found on the abfrontal face of the internal branchial and internal peduncular nerves of most of these serpulids. External branchial muscles are well developed in Pomatoceros, reduced in Serpula, Hydroides, Vermiliopsis, and Spirorbis militaris, and apparently absent in Protula and Spirorbis corrugatus. The pinnules of Pomatoceros and Hydroides, like filaments and opercular peduncles, have a double innervation. The internal skeleton of the serpulid crown consists of sheets and strands of connective tissue-fibres and, in the opercula, of a cartilage-like tissue with a ground substance giving the staining reactions of collagen. The serpulid branchial skeleton is compared with that of sabellids, and the chemical nature of these skeletons is discussed. Extensions of the prostomial and peristomial cavities accompany the branchial blood-vessels into the base of the crown, but have no connexion with the cavities in the branches of the crown. The arrangement of the latter is described. The nature of all these cavities, whether coelomic or blastocoelic, is obscure. The ‘palps’ of Pomatoceros, Serpula, Hydroides, and Vermiliopsis closely resemble pinnules. The blood-vessel and nerve of the ‘palp’ of Pomatoceros are branches of those in the adjacent filament. It is suggested that the serpulid ‘palp’ is a modified pinnule.
On the Functional Morphology of the Alimentary Tract of Some Fish in Relation to Differences in their Feeding Habits : Cytology and Physiology
Authors: Al-Hussaini A. H. 
Published: April 2021

ABSTRACT
1. The free border of the intestinal absorptive cells of cyprinids is nearly similar to that in tetrapods. This border has been described for four other species of fish and the possible evolution of the border from a ciliated epithelium has been described.
2. The mitochondria of the absorptive cells are arranged in a supranuclear group of mainly rod-like bodies and a subnuclear group of mainly granular ones.
3. The mitochondria are coarser and the Golgi element more readily impregnated with osmium tetroxide in the carnivorous Gobio than in the omnivorous Rutilus or the herbivorous Cyprinus. In all three fish both organoids are associated with fat absorption.
4. The goblet cells secrete both mucus and zymogen. Their stomata are permanently open.
5. Granular cells are described in Rutilus and Cyprinus, and in seven other species of fish, but they are absent from Gobio. Their varying reactions to numerous cytological techniques are described.
6. Alkaline phosphatase is especially concentrated in the free border of the absorptive cells. It occurs along the whole length of the gut. Its possible role in the absorption of fat and glucose is discussed.
7. Lipase is secreted by the absorptive cells. Fat absorption occurs along the whole length of the intestine, but the second limb of the intestine is especially active in this respect.
8. Carbohydrases and lipases are more concentrated towards the anterior end of the gut, whereas proteinases are more abundant caudally.
9. Carbohydrases are richer in Cyprinus and Rutilus than in Gobio.
10. Zymogen and lipase secretions are more concentrated in Gobio (carnivorous) than in the other two species.
11. The pH of the intestine of all three fishes is round about neutral point. Free HC1 is absent from all three.
The Distribution of Alkaline Phosphatase in Relation to Calcification in Scyliorhinus canicula : Development of the Endoskeleton
Authors: Joan Lorch I. 
Published: April 2021

ABSTRACT
1. A histochemical study has been made of alkaline phosphatase in the endoskeleton of dogfish embryos of 18-115 mm
2. The distribution of phosphatase is compared with that of insoluble calcium salts.
3. Phosphatase was first noted in the chondrocytes and perichondrium at 47 mm. and in the cartilage matrix at 58 mm.
4. Calcification occurred first in the neural plates at 58 mm. and in the skull at 74 mm. No calcification was observed in zones devoid of extracellular phosphatase.
5. As the intensity of calcification increased the amount of phosphatase tended to drop.
6. It is concluded that in elasmobranchs, as in higher animals, extracellular phosphatase is an essential precursor of calcification.
Low Viscosity Nitrocellulose for Embedding Tissues
Authors: Chesterman W. , Leach E. H. 
Published: April 2021

ABSTRACT
Low viscosity nitrocellulose may be used as a cheap and effective substitute for celloidin. A plasticizer, tricresyl phosphate, should be added to the embedding mass. The technique for embedding, cutting, and handling the sections is described. Sections can be cut with any ordinary paraffin microtome. It is easier to use than celloidin and considerably thinner sections can be obtained.
Studies of the Egg of Bacillus libanicus (Orthoptera, Phasmidae) : II. Moisture, Dry Material, and Minerals in the Developing Egg
Authors: Moscona A. 
Published: April 2021

ABSTRACT
1. Weight, moisture content, and mineral content of freshly laid and of fully developed eggs of Bacillus libanicus (Uv.) were studied. During development of the embryo the egg-shell loses 19 per cent, of its initial mineral content, while the weight of mineral materials in the embryo increases correspondingly.
2. These changes can be explained only as resulting from transfer of minerals from the shell to the embryo. The mineral materials are derived from the calcium carbonate layer of the shell, which, owing to this loss, becomes thinner during embryonic development.
3. It is suggested that the mechanism of this transfer is based on the production of bicarbonate by the reaction of water and carbon dioxide, given off by the embryo, with the calcium carbonate of the shell.
4. Experimental calcium deficiency in the egg-shells results in a marked lowering of the viability of the embryos; although embryogenesis may sometimes proceed till the hatching stage, the few emerging nymphs survive only for a short time.
5. The possible occurrence of mineral transfer in other phasmid eggs is indicated.
Alkaline Phosphatase in Protonephridia of Terrestrial Nemertines and Planarians
Authors: Danielli J. F. , Pantin C. F. A. 
Published: April 2021

ABSTRACT
1. Application of the Gomori method to sections of the terrestrial nemertine Geonemertes dendyi shows that there is no alkaline phosphatase in the flame cells or in the distal glandular canal of the protonephridia. But the proximal ciliated convoluted canal and the branching ciliated terminal ducts are rich in this enzyme.
2. Sections of the terrestrial triclad Rhynchodemus terrestris show the presence in the parenchyma of numerous ciliated convoluted canals resembling those of the nemertine.
3. A study of the protonephridial system of R. terrestris shows that this consists of numerous flame cells connected by branching unciliated ducts with the phosphatase- rich ciliated convoluted canals. The latter connect with unciliated distal canals which probably connect with the numerous exit ducts. These exit ducts are apparently confined to the ventral surface, particularly along the ciliated creeping sole.
4. The convergence between these nemertine and turbellarian protonephridia, and their analogy with the differentiated tubule system of the vertebrate kidney, are noted.
Observations on the Ligament of Mytilus edulis
Authors: Trueman E. R. 
Published: April 2021

ABSTRACT
The ligament of Mytilus edulis is situated between the valves of the shell immediately below the dorsal margin and may be divided into two main layers, the inner and the outer, the principal features of which appear to correspond with those of other bivalves. The outer layer is subjected to a tensile strain transverse to the longitudinal plane of the shell, which is imposed by the addition of the inner layer. This strain is increased when the valves are closed. At the same time the inner layer is compressed. It is significant, however, that the birefringence of the main outer layer is much smaller than in Tellina. The prodissoconch has a small internal ligament which is replaced by the normal adult structure as the posterior dorsal margin of the young mussel is extended. The axis about which the valves open is situated along a line drawn between the two main layers. Anteriorly the adult ligament becomes split and ceases to function. Possible explanations are suggested.
The Swimming Setae of Daphnia carinata
Authors: Agar W. E. 
Published: April 2021

ABSTRACT
The structure, renewal, embryonic development, and regeneration of the swimming setae of Daphnia carinata are described. Each seta is formed by four giant cells, two (the core cells) forming the distal segment, and two (the sheath cells) the proximal segment. The inner ends of these cells extend back, as the seta strand, through the whole length of the rami of the antenna to be inserted into the hypodermis half-way down the protopodite. The proximal segment of the seta is formed as an inverted sac, enclosing the distal segment. At ecdysis, the sac is everted. The mechanics of the extrusion of the new setae at ecdysis are described. In embryonic development the seta-forming cells are greatly enlarged hypodermal cells, which grow back from the tip of the antenna to the protopodite. The primary embryonic setae consist of the distal segment only of the adult seta. If a ramus of the antenna is amputated, the missing segments are never regenerated. Formation of new setae takes place, however, from the hypodermal membrane which grows across to close the wound. These setae are formed in the same way as in embryonic development. The muscles in the segment through which the amputation was performed degenerate and are not replaced. The potentiality of enlarging and becoming a seta-forming cell is possessed throughout life by all the hypodermal cells of the two rami of the antenna, but not, apparently, by the cells of protopodite hypodermis.
The Blood-system in the Serpulimorpha (Annelida, Polychaeta): II. The Anatomy of the Blood-system in the Sabellidae, and Comparison of Sabellidae and Serpulidae
Authors: Hanson Jean 
Published: April 2021

ABSTRACT
The blood-system in sabellids of the following genera is described: Sabella, Potamilla, Branchiomma, Dasychone, Amphiglena, Fabricia, Jasmineira, Dialychone, and Myxicola. The central blood-system of Sabella is typical of the family, but the peripheral blood-system is variable. The dorsal vessel lacks the valve and muscular sphincter found in some serpulids. Lateral vessels are present only in Sabella and Dasychone. The differences and similarities between sabellid and serpulid blood-systems are discussed. Special attention is given to the functions of sub-epidermal and coelomic capillaries and the blood-supply of the body-wall musculature.
The Respiratory Mechanisms of Some Insect Eggs
Authors: Wigglesworth N. B. , Beament J. W. L. 
Published: April 2021

ABSTRACT
By the use of the cobalt sulphide injection technique the distribution of air in the shell of a number of insect eggs has been studied. Air is usually confined to an inner layer of porous protein, connected with the atmosphere through pores of varying type which are likewise filled with spongy material.
In Rhodnius the ‘resistant protein layer’ which lines the shell is the porous structure and the ‘pseudomicropyles’ connect this layer to the exterior. The arrangement in Cimex is similar. In Oncopeltus the spongy walls of the ‘sperm cups’ convey air to a porous inner layer. After laying, the lumen of each cup (the micropylar canal) is occluded with solid cement.
In Dixippus the so-called ‘micropyle’ in the ‘scar’ of the egg is the respiratory pore. It is filled with spongy protein containing air and conducts the air to the spongy inner layer of the endochorion. As the egg develops and its contents are reduced in volume, free air collects between the two layers of the endochorion in the region of the pore.
In Blattella an elaborate stigmatic apparatus which is moulded in the crista of the oötheca conveys air to a spongy process at the upper pole of the egg and so to a thin porous air-filled layer which lines the chorion.
In Bombyx and Ephestia a thin porous inner layer of the chorion containing air communicates with the exterior through scattered pores containing air-filled spongy material.
In the eggs of Diptera the chorion consists of tapering columns with spongy walls which unite the cement-covered outer layer to a spongy inner layer containing air. The horns on the Drosophila egg and the dorsal folds on the Calliphora egg provide respiratory outlets for this system. The spaces between the columns contain liquid in Calliphora and Drosophila-, in Syrphus these spaces are greatly enlarged and contain air.
The spongy layers may become filled with air in eggs which are still bathed in fluid in the oviduct, or in which water is present in adj acent parts of the shell. The mechanism of filling is discussed.
In the case of Rhodnius there is quantitative evidence that the system will provide for the respiratory needs of the egg.
The Organization of the Muscular System of Metridium senile
Authors: Batham E. J. , Pantin C. F. A. 
Published: April 2021

ABSTRACT
The muscular system of Metridium consists of fields of relatively short musclefibres. In extension these may exceed i mm. in length but are only about 0-5/2 thick. They can shorten to about a fifth of the extended length. The fibres consist almost entirely of densely staining material. They form a connected network. At least in some cases the cells seem to be in contact rather than to form syncytial connexions. Deformation of the body-wall is in part controlled by the contractility of the muscle-fibres and in part by the properties of the mesogloea. Longitudinal contraction of the body-wall is accompanied by great thickening of the substance of the mesogloea. That part of the mesogloea which carries the circular muscle-fibres of the body-wall does not thicken. It buckles, thereby throwing the muscular layer into folds. Buckling occurs during the shortening of almost every actinian tissue. The familiar folding seen in cross-sections of the retractors is a special case of excessive buckling which is permanent. A natural limit to the extension of anemone tissue is reached when the musclelayer is completely unbuckled. If contraction proceeds to a maximum, there is a second order of buckling by which the whole body-wall is thrown into folds. Contraction can then proceed no further. The function of the muscle-fields is analysed. The youngest cycles of mesenteries (‘imperfect microcnemes’) supply the longitudinal musculature of the column (parietal muscle). The older ‘imperfect retractor-bearers’ have only feeble parietal musculature, but possess a retractor muscle connecting the oral with the pedal disk. The perfect mesenteries have a similar organization to the imperfect retractor-bearers, and particularly in the non-directive perfect mesenteries there is a well-developed sheet of radial (exocoelic) muscle whose reflex contraction opens the mouth. The vertical endocoelic muscle-fibres of all non-directive mesenteries fan out on to the pedal disk. On the exocoelic side, the parieto-basilar fans out from the pedal disk to the body-wall. As usual, the muscle-fields of the directives are developed on opposite sides from those of the non-directives. The muscular plan of the pedal disk is compared with the tube foot of Asterias as described by J. E. Smith. There is a significant functional similarity in the operation of vertical, oblique, and radial muscles (basilars) bearing on the adhesive disk. The circular layer of the actinian foot has no analogue in the tube foot. It is primarily concerned with locomotion and not with adhesion. The functional organization of the oral disk and tentacles is discussed. It differs from the rest of the body in the retention of ectodermal longitudinal muscle. This layer is responsible for the special movements executed in feeding. The significance of its physiological separation from the endodermal system is noted.