bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms for the Prevention of Self-Fertilization in some Species of Fresh-Water Triclads
Authors: Ullyott P. , Beauchamp R. S. A.
Published: April 2021

Experiments by Gelei (1924) show that some very effective mechanism for the prevention of self-fertilization does exist in Dendrocoelum lacteum. When kept alone from the time of hatching, this species produced cocoons containing eggs which had not been fertilized. Two such animals which had both produced unfertile eggs while isolated, after pairing laid cocoons containing fertile eggs.
The Structure of the Otolith of the Hake
Authors: Hickling C. F.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
The Absorption of Lipoid by the Intestinal Epithelium of the Mouse
Authors: Baker John R.
Published: April 2021

During the absorption of fat by the intestinal epithelium of the mouse, spindle-shaped particles of lipoid material can be seen in the free border of the epithelial cells. The spindles, which he with their axes at right angles to the surface of the free border, correspond in position with the spindle-shaped canals previously described by the author in various vertebrates.
Phosphatases and Nucleic Acids in Silk Glands: Cytochemical Aspects of Fibrillar Protein Secretion
Authors: Bradfield J. R. G.
Published: April 2021

Silk glands of several spiders and caterpillars contain powerful .cytoplasmic phosphatase activity localized along the inner border of the cells next to the gland lumen. Phosphatase activity is also high in the nuclei, particularly the nucleoli. Reservoir regions which secrete no silk lack the phosphatase border.

Although it is most easily demonstrated histochemically at pH 9, phosphatase activity in sections or homogenates of the glands is high over a considerable range of pH, from at least pH 5·5 to pH 9·8. It appears to be inhibited both by sulphydryl inactivators and by an abundance of sulphydryl groups. In view of the latter point, it is interesting to note that no sulphydryl groups can be detected in the phosphatase border zone (in the more insoluble constituents which remain in formalin-fixed frozen sections), although the main bulk of the cytoplasm is rich in sulphydryl groups.

Except in the non-secretory reservoir regions, silk glands of all the species examined are rich in cytoplasmic ribonucleic acid. Although the latter is abundant in the main body of the cell, it is, however, absent from the phosphatase border zone, so that in the cytoplasm nucleic acid ends where phosphatase begins.

This suggests that the phosphatase may be part of a system of enzymes involved in liberating the finished protein from a complex with nucleic acids (which have been concerned either in the synthesis of the protein, or in protecting it from proteases, or both). This possibility is discussed in the light of previous studies of phosphatase-nucleic acid relations in other tissues.
The Formation of the Ootheca by Periplaneta Americana : I. The Micro-anatomy and Histology of the posterior part of the Abdomen
Authors: Brunet P. C. J.
Published: April 2021

The ootheca is of interest because it is composed of quinone-tanned protein. No detailed account of the secretory processes leading to the production of structural protein and tanning agents exists, and this paper is intended as an introduction to such a cytological and histochemical account; it contains a description of the general anatomy of the organs concerned with the formation of the ootheca. These organs are located round the vestibulum, a large intucking of the posterior part of the abdomen.

The colleterial glands open into the vestibulum and secrete most of the protein and tanning agent. The structure of each type of secretory cell of which the gland is composed is outlined.

A new organ, taking the form of a large invagination of the dorsal wall of the vestibulum, is described. The walls of this invagination are secretory, and it is notable that the secretion-product accumulates and is stored within the substance of a modified layer of the endocuticle.

Two types of massed dermal gland cells are described. One type is present mostly on the ventral walls of the ovipositor, and the other towards the posterior end of the vestibulum. The former may not be directly concerned with ootheca formation, while the latter probably secretes the alkali-resistant outer layer of the ootheca.

The relations between the ovipositor and the ‘horned die’ of Kramer and Wigglesworth are discussed.
Corpora lutea in an Ascidian, Ciona intestinalis
Authors: Carlisle D. B.
Published: April 2021

Corpora lutea are reported to be present in the ovary of Ciona intestinalis and are briefly described. They conform to the type known as pre-ovu1ation corpora lutea solida simplicia.
Preliminary Account of an Electron Microscope Study of Chromosomes from Newt Oocytes
Authors: Tomlin S. G. , Callan H. G.
Published: April 2021

Chromosomes from oocytes of the newt Triturus cristatus camifex have been photographed by means of the electron microscope. These chromosomes are shown to consist of single axial filaments, approximately 200 Å wide, with ‘lamp-brush’ loops attached at intervals along their lengths. Good fixation of the lamp-brush loops has not yet been obtained. These chromosomes are attached in pairs to their homologues at points which, in the past, have been considered to be chiasmata: it has been assumed that the stage is diplotene of the first meiotic division. The singleness of the chromosome strands which we have observed is at variance with observations of diplotene in other material by means of the light microscope.
Observations on Giant Fibres of the Nervous System of Locusta migratoria
Authors: Cook P. M.
Published: April 2021

There are four fibres of giant dimensions in each cord of the abdominal ventral nerve-chain of the locust. These fibres are the axons of large neurons situated in the extreme posterior region of the last abdominal ganglion, and run uninterruptedly through the abdominal nerve-chain to the metathoracic ganglion. Posteriorly these neurons synapse with preganglionic fibres which appear to be cereal nerve-fibres and anteriorly with motor pathways to the metathoracic legs.

Oscillographic observations have been correlated with those from the histological study. The possible function of these pathways has been discussed and comparison made with the cockroach, where a similar organization has been described in detail.
An Electron Microscopic Study of the Muscle-fibres of the Diaphragm
Authors: Bluhm M. M. , Sitaramayya C.
Published: April 2021

Myofibrils of rat diaphragm of various ages, in different states of activity, after denervation, and after acetyl choline contracture, were studied by electron microscopy. A comparative study of other rodent diaphragms and of human diaphragm was also made.

Myofibrils from diaphragm are similar to those of other striated muscles. The differentiation into A and I bands is due to differences in the substance present round the actomyosin filaments in those regions. The Z disk is extra-sarcomere; it-appears even before any differentiation of the fibril into A and I bands is recognizable. At the age of about 42 days, the myofibrils in rat diaphragm are completely differentiated and conform to the adult type. The sarcomere length in adult rat diaphragm is between 2 and 3 μ.

The adult rat diaphragm contains two types of fibrils which differ, though not sharply, in their extensibility and thickness.

The A and I bands react differently to a variety of stimuli. Thus, passive stretching affects the I band almost exclusively, while contraction affects both bands; here, again, the effect depends on the type of contraction; isotonic contraction shortens both A and I, whereas isometric contraction shortens A and lengthens I. In the denervated muscle the A band is shortened. On the whole, the A band seems to play the major role in contraction.

The H disk is intra-sarcomere and appears during contraction, especially when the muscle is stimulated in the stretched state. The M and N lines also are intra-sarcomere. Evidence regarding their nature and appearance is discussed.
The Action of Formaldehyde on Living Cells as Studied by Phase-contrast Microscopy
Authors: Crawford G. N. C. , Barer R.
Published: April 2021

The morphological changes occurring when living cells are fixed in neutralized formaldehyde have been studied in detail with phase-contrast microscopy. The cells used were (1) salamander spermatogonia obtained from the teased testis, and (2) snail amoebocytes growing in tissue culture. The cells were mounted on a slide beneath a coverslip ringed with paraffin wax. Various strengths of formaldehyde made up in saline or distilled water were then introduced while the cells were kept under constant observation by phase-contrast microscopy. The morphological changes during the fixation process were observed for periods of at least 24 hours and the results recorded photographically.
The Tegumental Glands in the Land Isopoda: C. The Lobed Glands: The Properties of their Secretion and their Mode of Action
Authors: Gorvett H.
Published: April 2021

The lobed glands of the Oniscoidea respond to appropriate stimulation by liberating droplets of secretion at the edges of the lateral plates and uropods. The fresh secretion is a clear fluid, which is soluble in water, contains protein, water, perhaps fatty acid, but not mucin, fat, wax, or glycogen. The uropod secretion is very sticky and viscous, slowly soluble in water, neutral in reaction, and without odour; the lateral plate secretion is a watery fluid, freely soluble in water, strongly acid in reaction, and with a pungent smell resembling that of butyric acid. Both secretions solidify rapidly on exposure to air, and both are coagulated by alcohol. Both types of gland secrete only in response to violent stimulation ; this must be both strong and sudden in its application, and often causes fatal injury. The uropod glands secrete more readily than the lateral plate glands. The amount of secretion varies in different individuals of the same species; it is not correlated with the age, sex, or moulting condition of the animal, but may depend on its general condition. The glands empty rapidly when stimulated, cannot repeat the process except at relatively long intervals, and appear to be incapable of secreting continuously. They do not appear to be under nervous or hormonal control, but may be emptied passively by contraction of neighbouring muscles. The significance of these results in relation to the problem of function is discussed.
The Formation of the Ootheca by Periplaneta americana: II. The Structure and Function of the Left Colleterial Gland
Authors: Brunet P. C. J.
Published: April 2021

The anatomy of the left colleterial gland of the cockroach is described. It is convenient to subdivide the gland into four regions. At the posterior end, abutting on to the outlet of the gland, there is no secretory activity and the cells of this region are not unlike normal epidermal cells. Anterior to this region are the three secretory regions of the gland ; of these, the anterior and posterior secrete the structural protein and the constituent cells are equipped with a complex end-apparatus, a thick-walled depression in the apex of the cell in which the final stages of the elaboration of the secretion occur. The body of the end-apparatus contains canalicules which lead to the lumen of the gland. Alkaline phosphatase is abundantly present in this organ. Protein is secreted continuously, and there is no cycle related to oviposition. The third region, between the protein-secreting regions, secretes an oxidase, whose function may well be to oxidize the phenolic tannin-precursor produced in the right colleterial gland when the products of the two glands come together at oviposition.

The gland becomes fully functional some 14 days after the final moult, the immature cells of the nymph developing directly into mature cells characteristic of the region in which they occur. Within each of the main regions the cells show some differences which suggest that there is a wave of change passing along the gland. It appears that the cells of the anterior end of the gland become defunct and the hitherto inactive cells of the posterior end take on a secretory function.

The structural protein has a high phenolic content, and contains no combined carbohydrate. The presence of lipoid in the secretory cells appears to be directly bound up with the secretory processes.
The Multiplication of Vaccinia Virus in Tissue Cultures of Adult Rabbit Skin
Authors: Crawford G. N. C. , Sanders F. K.
Published: April 2021

The optimum conditions for vaccinia virus multiplication in shavings of adult rabbit skin maintained in rocker flasks in a fluid medium have been investigated. Satisfactory virus multiplication occurred in 5 ml. of medium containing 40 per cent, rabbit serum, 40 per cent, phosphate-buffered saline, and 20 per cent, mouse embryo extract; an air atmosphere was used. A growth curve for vaccinia virus grown in vitro under these conditions was obtained by estimating the virus content of cultured skin at known intervals after inoculation. The curve was essentially similar to that obtained by growth of vaccinia in vivo, and could be divided into three phases : (a) during the first few hours infectivity fell, (b) from 10 to 40 hours there was a rapid increase of infectivity, and (c) flattening of the curve started after 40 hours, although some increase of virus continued, until, at 80 hours, the concentration of virus present was at a maximum. An attempt is made to correlate the multiplication of virus with the cytological changes known to occur in infected cells.
The History of the Cytoplasmic Elements During Vitellogenesis in Drosophila Melanogaster
Authors: HSU W. SIANG
Published: April 2021

1. At least two kinds of yolk are developed in the eggs of Drosophila melanogaster. The origin of the proteid yolk has been traced to precursors sent into the oocyte by the nurse cells, while the minute fatty yolk granules are transformed chondriomites also contributed by the nurses. The behaviour and morphology of Golgi material in the nurses indicate that it may be responsible for a third type of yolk.

2. A yolk nucleus has been found in oocytes of an age when the germinal disk has been pushed to one side. So long as such a structure exists, all the proteid yolk precursors are concentrated and matured within its confine. Soon this structure disintegrates and disappears. But after its disappearance, yolk precursors continue to be sent by the nurses into the oocyte, and there they develop into mature granules apparently without the benefit of a yolk nucleus. On the basis of facts thus far obtained, it is, therefore, difficult to say just what role the so-called yolk nucleus plays in vitellogenesis in Drosophila melanogaster.

3. Golgi material in the nurse cells has been observed to undergo two distinct proliferations. In young nurses, Golgi material occurs in a few discrete bits which, as the nurses grow in size, proliferate into a large number of intertwining threads so arranged as to suggest a net. Then follows a period in which only very few minute granules of Golgi material can be seen. This is definitely a period of scarcity. After this, a second proliferation takes place. This one is carried to such an extreme extent that the cytoplasm of the cells is just black with Golgi material. The Golgi threads, arranged more or less in a parallel fashion and very closely together, present the appearance of pieces of Golgi ‘tissue’. Next, the pieces of ‘tissue’ loosen up into separate threads from which individual Golgi granules arise. These granules enlarge to become vesicles.

4. In the course of development of the nurse cells, the mitochondria also undergo a proliferation. Finally, the chondrioconts break up into granules which enlarge and eventually all transform into droplets of unsaturated fat.

5. My observations point to the conclusion that the oocyte depends upon its nurses for the production of fatty yolk. Proteid yolk granules, however, are developed within the oocyte, though from precursors sent in also by the nurse cells. The follicular cells do not appear to contribute anything to vitellogenesis in Drosophila.

6. An idiosome-like granule has been observed in oogonia, and also in oocytes up to a certain stage of development. For reasons stated elsewhere, it cannot be regarded as an idiosome nor as a centrosome. This structure has not been observed in nurse cells.
Modes of Gastrulation in Vertebrates
Authors: Waddington C. H.
Published: April 2021

The modes of gastrulation in the different classes of Vertebrates are discussed from a comparative point of view, with the particular aim of finding some system which avoids postulating a sharp dualism between the anamniote telolecithal forms, in which the edge of the blastoderm consists of presumptive endoderm, and those of the Amniotes, in which it is ectodermal. It is suggested that the most profitable way of regarding all blastodermic forms is to envisage them as derived from the basic type of blastula by a process in which the roof and floor are squeezed together, so that a flatfish double-layered plate is produced. The concept of the ‘primitive edge’ of such a blastoderm is introduced, and it is suggested that in the amniotes the presumptive ectoderm has expanded greatly beyond the primitive edge, while there has also been a strong convergence towards the dorsal side. The conditions in certain highly yolky amphibian eggs are shortly described, and it is argued that they show conditions similar to those which would be expected on the hypothesis of a squeezing together of the blastula roof and floor.
Cyclic Changes in Polysaccharides of the Papilla of the Hair Follicle
Authors: Montagna William , Chase Herman B. , Malone Janet D. , Melaragno Helen P.
Published: April 2021

In the skin of the mouse the dermal papilla becomes metachromatic and PAS-reactive on the 4th day after the initiation of growth in the hair follicle. This is a stage of follicle development which immediately precedes hair proliferation. Both metachromasia and PAS reaction remain intense until about 18 days, just preceding catagen, or club formation, when they disappear abruptly. During telogen, or the resting stage, the papilla is neither metachromatic nor PAS-reactive. The metachromasia and the PAS reaction of the dermal papilla during the period of active hair proliferation indicate the presence of at least two polysaccharides which are not detectable during the remainder of the cycle.
Internode Length in the Skin Plexuses of Fish and the Frog
Authors: Whitear Mary
Published: April 2021

Measurements made in the skin plexuses of teleosts and of Rana have shown that the internode lengths of myelinated fibres may here be shorter than the ‘minimum internodal length’ previously reported.
Growth and Cellular Proliferation in the Early Rudiments of the Eye and the Lens
Authors: Balinsky B. I.
Published: April 2021

It is well known that unequal growth is a major factor in establishing the proportions of the body in animals. It is not so clear what part unequal growth plays in the earlier phases of morphogenesis, that is, in stages when the organ rudiments are first formed and acquire their general shape. The growth of the embryo has been studied successfully in many animals, but not much has been made known concerning the growth processes in stages when the organ rudiments are being formed. In previous papers I have examined the growth and cellular proliferation in the earliest rudiments of the mammary glands (Balinsky, 1950a, 19506). I have now found it desirable to investigate the same processes in organ rudiments of a different type. The organ selected was the lens of the eye throughout the period when it is being formed from cells of the embryonic epidermis. I have also studied the growth of the eye cup in the same stages for comparison.
Observations upon the Recovery of Oxyntic Cells after Prolonged Dosage with Pilocarpine or Histamine
Authors: Menzies Gordon
Published: April 2021

New observations are presented concerning the structure and cytochemistry of the granules in the oxyntic cells of the rat ‘s stomach, in continuation of work already reported (Menzies, 1949, 1952 a and b). The phospholipine component of the granules is slowly regained after being depleted by multiple doses of pilocarpine or histamine. The phospholipine is first regained by the granules in those oxyntic cells situated at the basal ends of the gastric tubules, and later by the remaining cells in the neck of the tubules. An acid phosphatase appears in the oxyntic cells whose granules are about to regain their lipine component, and disappears some time after they have done so. The order in which both the acid phosphatase and the lipine appears (first in the basal cells and later in cells in the neck region) is the same as that in which an acid phosphatase appears when and as the lipine is being shed under experimental conditions (Menzies, 1952 b).
The Cytoplasmic Cytology of Sarcoma 180
Authors: Worley Leonard G. , Spater Herman W.
Published: April 2021

Sarcoma 180 is one of the transplantable, non-metastasizing, connective tissue tumours of the mouse. A bit of sarcoma material, not exceeding 2 mm. in diameter, implanted beneath the skin of the breast as described by Zahl and Drasher (1947), grows within a fortnight into a conspicuous malignant tissue of such proportions that the host usually soon succumbs. Although studies have been made on the nuclear and cytoplasmic cytology of this and closely related tumours (Levine, 1939; MacCardle, 1951, and others), and Ludford and Smiles (1950) have recently compared the structure of mouse sarcoma cells with that of normal fibroblasts as seen in phase-contrast and ultra-violet micrographs, little pertinent work has been published regarding the finer cytological details and there is essentially no information available regarding the cytochemistry of the cytoplasm and its inclusions.
The Development and Structure of the Anterior Region of the Body in the Sabellariidae, with special reference to Phragmatopoma californica
Authors: Dales R. Phillips
Published: April 2021

Attention is drawn to the confusion which has been caused by the loose terminology of the anterior appendages in polychaetes, and more exact connotations are proposed. As the prostomium can be recognized as a comparable unit throughout the Polychaeta, a consideration of its constitution is deferred.

In the present paper the development and constitution of the anterior region of the sabellariid worms are considered. The larval development of Phragmatopoma californica (representing the most highly advanced genus) is described, and the structure of the adult of this species is compared with that of species belonging to other genera.

It is concluded that the opercular stalk arises mainly from the first segment ; that the opercular paleae represent the notochaetae of the first two segments, and that the oral tentacles and the building organ are also developed from the first segment. The prostomium bears a single pair of tentacles.
Experiments on Vital Staining with Methylene Blue
Authors: Harris John E. , Peters A.
Published: April 2021

Some four years ago, with the help of Miss L. Morris, one of the present authors developed a new method of vital staining of the nervous system of the embryo dogfish, Scyliorhinus canicula, using a modification of the old-established rongalit methylene blue technique. The success of this method led to an experimental study of some of the factors involved, and the present account deals mainly with these studies. The work is concerned almost entirely with the penetration of the stain into the tissues; the part, if any, played by the specific chemical combination of nerve-cell constituents with the dyestuff in its final site is not considered.