bluuebunny/crossref_metadata_2025 huggingface dataset:
The Histochemistry of the Male Germ-cells of the Nematode Porrocaecum angusticolle, a Parasite in the Vulture
Authors: Nath Vishwa , Gupta Brij L. , Kochhar Devendar M.
Published: April 2021

The cytoplasm of the male germ-cells of Porrocaecum angusticolle contains (1) phospholipid granules, (2) ‘refringent bodies’ consisting of ribonucleoproteins at first, but some masked lipids as well in the late spermatid, (3) mitochondria of the usual lipoprotein nature. The refringent bodies arise in the spermatocytes in close association with the phospholipid granules (‘Golgi bodies’) by the aggregation of cytoplasmic basiphil material. In the spermatids the refringent bodies gradually fuse to form a single cone-like structure which occupies the narrow posterior region of the spermatozoon.

This cone-like structure, judging from its origin in close association with the ‘Golgi bodies’ (acroblasts), is the homologue of the acrosome of a normal flagellate sperm; but it is completely devoid of polysaccharides and seems unable to function as an acrosome, since it occupies a position posterior to the nucleus in the spermatozoon. On the contrary, some polysaccharides have been demonstrated by the authors in the broad anterior region of the spermatozoon, which may be functioning as an acrosome.
The Histochemical Recognition of Lipid in the Cytoplasmic Network of Neurones of Vertebrates
Authors: DAVID G. B. , BROWN A. W.
Published: April 2021

1. A method for the histochemical demonstration of the lipid of the cytoplasmic network (‘Golgi apparatus’, ‘Nissl complex’) of the neurones of vertebrates was accidentally discovered.

2. Very small pieces of tissue are fixed in Lewitsky/calcium or Flemming/calcium, postchromed, and embedded in gelatine. Frozen sections are cut at 0.5 to 5 µ, and coloured in Sudan black after bleaching.

3. The intensity of the colouring of lipid by Sudan black can be increased by centrifuging the tissue before fixation.

4. The method described in this paper demonstrates lipid in the strands and bodies of the cytoplasmic network of vertebrate neurones. It was shown, in sections subsequently decolorized and then stained in a basic dye, that the sudanophil reticular objects are the Nissl complex.
A Histochemical Study of the Connective-Tissue Sheath of the Nervous System of Periplaneta americana
Authors: Ashhurst Doreen E.
Published: April 2021

The connective-tissue sheath surrounding the nervous system of Periplaneta americana consists of two layers, the neural lamella and the sheath cells beneath it. The neural lamella is composed of a collagen-type protein and neutral muco-polysaccharide. The sheath cells possess numerous lipochondria and mitochondria; the former consist of phospholipid and some cerebroside. The cytoplasm of the sheath cells contains some RNA, glycogen, and lipid.
Stress concentrations in bone
Authors: Currey J. D.
Published: April 2021

Small cavities and notches in an otherwise perfect material will greatly reduce the strength of the material, particularly its tensile strength. They will do this by producing stress concentrations around themselves. It is shown that bone is permeated with such stress-concentrators in the form of canaliculi, osteocyte lacunae, blood-vessels, and muscle insertions. However, in mammalian bone the orientation of the lacunae and blood-vessels is such as to reduce, though not abolish, the concentrating powers of these elements in relation to the dangerous stresses acting in the bone. The smoothness of the diaphysis shaft and the raising of muscle insertions on to cristae will have similar advantageous effects. The larger the defect, the greater the tendency to be orientated favourably.

The reasons for the presence of osteocytes and their associated blood-supply are not known, and a comparison with the acellular bone of some teleosts is not helpful. It is suggested that the lacunae and blood-channels in bone may to some extent increase the robustness of bone by delaying the spread of minute cracks, which must inevitably be present in bone, though they are difficult to demonstrate. The orientation of the lacunae is favourable for this effect, and they are sufficiently close-packed in the bone to ensure that any minute crack will run up against many lacunae before it has travelled roo y.. An examination of artificially produced cracks in cattle and human bone shows that the cracks do stop very frequently on entering lacunae and blood-vessels. The lacunae are more likely to prevent the spread of fatigue cracks than of impact cracks. The crack, running up against a lacuna, could be a stimulus for local reconstruction, so that it would be repaired.
The influence of mature males on the neurosecretory control of ovarian development in the desert locust
Authors: Highnam K. C. , Lusis O.
Published: April 2021

The ovaries of the desert locust are made up of about 100 ovarioles. When females are reared with mature males, the terminal oocytes in the ovarioles develop very much more rapidly than the terminal oocytes of females reared without males. In addition, the percentage of terminal oocytes which are resorbed during development increases more rapidly in females reared without males than in females reared with mature males. This results in a significantly larger percentage of mature eggs being produced by females reared with mature males.

The neurosecretory system contains little stainable material in females whose terminal oocytes are developing rapidly in the presence of mature males, but contains a large amount when the terminal oocytes are mature. In females reared without males, whose terminal oocytes either develop slowly or remain undeveloped, the neurosecretory system shows a precocious accumulation of stainable material. It is concluded that the neurosecretory system is actively extruding secretion when the amount of contained material is small, and that material is accumulating and not being released when it is present in large amount. The presence of mature males somehow brings about the release of material from the female neurosecretory system, with consequent rapid development of terminal oocytes and the production of a larger number of eggs.
A study of Thermosbaena mirabilis (Malacostraca, Peracarida) and its reproduction
Authors: BARKER D.
Published: April 2021

Knowledge of the anatomy of Thermosbaena is extended as follows: (i) The topography of the head and anterior thoracic region, and the orientation and relationships of the mouthparts and anterior appendages are described, (ii) A branchial chamber is located underneath each lateral carapace flap, (iii) ‘Skin’ glands are demonstrated to occur at the bases of the paragnaths, maxillules, and maxillipedes; in the labrum and in the mandibular palps; in the groove leading from the food basin to the paragnath bases; and in the basal segments of the endopodites of peraeopods II-V. The function of these glands is obscure; histochemical tests indicate that they do not secrete mucus, (iv) The posterior aorta is traced from the heart to the level of the first abdominal segment, where it bifurcates into 2 lateral vessels which diverge to each side of the intestine, (v) Four conditions of the female reproductive system are distinguished, namely, the immature, mature, copulatory, and brood-pouch conditions; temporary seminal receptacles are formed by dilatation of the oviducts in the copulatory condition.

An inhalant respiratory current is produced by oscillation of the maxillipede epipodites in the branchial chambers. The exhalant respiratory current emerges via carapace lappets on either side of the head.

Thermosbaena feeds on particles of detritus suspended in a mucilaginous matrix that is probably derived from the mucilaginous sheaths of the Cyanophyceae in the diet. A main food-stream appears to be driven forwards between the peraeopods, through a channel formed by the maxillipede bases to the food basin, and from thence along a ventral groove and between the paragnath bases to the oral cavity. It is possible that the main food-stream is augmented by detritus brought by the inhalant respiratory current, and by lateral feeding currents drawn in from the sides.

Following internal fertilization, early segmentation of the embryo occurs within the ovaries. The blastomeres are first formed within the body of the yolk and subsequently rise to the surface, the segmentation thus resembling that of Hemimysis and Mesopodopsis. The embryos are transferred to the dorsal brood-pouch shortly after segmentation begins, probably by expulsion from the posteriorly directed vaginae while the female is upside down, followed by suction into the brood-pouch with the inhalant respiratory current. The embryos emerge from the brood-pouch as miniature adults with the full complement of peraeopods. There appears to be no transitory 7th abdominal ganglion.

Thermosbaena is probably paedomorphic in certain respects and less primitive than Monodella. There are insufficient grounds for establishing a new malacostracan division Pancarida, as advocated by Slewing (1958), to receive the Thermosbaenacea.
Cyclical changes in the epididymis of the goose, Anser melanotus
Authors: Mehrotra P. N.
Published: April 2021

The epididymis of Anser melanotus consists of three components, the rete testis, vasa efferentia, and epididymal tubules. The histological structure and the relationships between the three components of avian epididymis are similar to those existing in the mammalian epididymis. The epididymis shows periodic changes in its histological structure, which are parallel to the changes in the testis.

The rete testis consists of wide, anastomosing, cavernous channels, the rete tubules, lines with a simple non-secretory epithelium of cuboidal and columnar non-ciliated cells. During the breeding season the diameter of the rete tubules undergoes an appreciable increase. The internal epithelium becomes squamous through considerable distension.

The efferent ducts are lined by groups of columnar ciliated cells alternating with non-ciliated cubical cells, both the types showing secretory activity in the progressive and reproductive phases of the testicular cycle. The internal epithelium of the efferent ducts is thrown into longitudinal folds, leading to the formation of crests and crypts, which give a festooned appearance to the lumen.

The epididymal tubules are lined with columnar ciliated cells. During the onset of reproductive period, the epithelial cells of the epididymal tubules hypertrophy and become secretory. The secreted droplets are discharged into the tubule lumina. During the breeding season the epididymal tubules are filled with sperms. In the refractory phase of the testis cycle the epididymal tubules present an embryonic appearance and have no limiting membrane. Groups of cells similar to those which constitute the lining of the tubules can be seen. These cords of cells become bigger by the division of the pre-existing cells and lumina then appear in the centre, leading to the formation of new tubules.

The epididymal secretion gives a stimulus to the spermatozoa different from that given by the testis; it brings about the ripening changes in the spermatozoa.

There is no influence in the epididymis which can indefinitely preserve the vitality of sperms. The unejaculated spermatozoa left over in the epididymis after the breeding season is finished, either undergo dissolution in the lumina of the tubules or penetrate into the epithelial lining of the efferent ducts and epididymal tubules or even into the surrounding connective tissue, to undergo degeneration there.
The structure and function of the so-called yolk-nucleus in the oogenesis of birds
Authors: Guraya Sardul S.
Published: April 2021

The so-called yolk-nucleus of the young oocytes of birds is situated close to the nucleus. It is a homogeneous, spherical mass with radiating projections. Histochemical tests show it to be rich in RNA. Lipid bodies of diverse nature and mitochondria are aggregated in its vicinity. The yolk-nucleus disintegrates as the yolk-bodies are formed, and meanwhile the cytoplasmic inclusions that had aggregated round it seem to disperse and disappear. When the yolk-bodies have been fully formed, the yolk-nucleus is reconstituted once more as a homogeneous, spherical mass.
The action of phenyl-thiourea on melanogenesis in Xenopus laevis
Authors: Sims R. T.
Published: April 2021

From Xenopus laevis tadpoles which possessed conical hind-limb buds with pigmented melanophores the caudal two-thirds of the tail was amputated. One group of these animals was kept in tap-water and another group in 0·01% phenyl-thiourea in tapwater while regeneration of the tails took place. After one month the tails of the operated animals together with tails from a control group of normal animals at the same stage of development were examined histologically. In the normal tail melanin was only absent from the region of the ventral fin immediately behind the anus: in the untreated regenerate melanin was only absent from the major part of the ventral fin: in the treated regenerate melanin was absent from the whole regenerate. Branched DOPA-positive cells situated beneath the epidermis and each accommodated by a circle 0·05 mm in diameter were present in the normal tails, untreated regenerates, and treated regenerates. They were present only in the regions lacking melanophores in the normal tail and untreated regenerate, but in the animals treated with phenylthiourea they were present in the unpigmented regenerate and in the pigmented part of the tail-stump. The pigmented melanophores were DOPA-negative. Cells which were stained by the hexamine-silver technique and Schmorl’s reaction were found only in the regenerate of the treated tadpoles. It is suggested that the DOPA-positive cells are potential melanophores. In the normal tail and untreated regenerate tyrosinase activity was present without promelanin granules and in the treated regenerate tyrosinase activity was present with promelanin granules. The negative response of pigmented melanophores could reflect a loss of tyrosinase activity as pigmentation of the granules is completed. Phenyl-thiourea does not inhibit melanogenesis in vivo by acting on a metabolic process essential for the normal activity of the cell, or by inhibiting the production and action of tyrosinase, or by preventing formation of promelanin granules, as these were all present in the treated animals. A test-tube experiment showed that phenyl-thiourea inhibits the autoxidation of DOPA. It is suggested that the drug acts by combining with an intermediate produced during the conversion of tyrosine to melanin.
Cytological evidence of adrenocortical activity in vitro
Authors: Casselman W. G. Bruce , Schönbaum E.
Published: April 2021

When stimulated by adrenocorticotrophic hormone, adrenocortical cells in vitro undergo cytological changes similar to those previously described for the intact animal.
Observations on a highly specific method for the histochemical detection of sulphated mucopolysaccharides, and its possible mechanisms
Authors: Heath I. D.
Published: April 2021

Whereas basic dyes in aqueous solutions stain chromatin, all mucins, mast cells, the ground substance of cartilage, and epidermis, it has been shown that a 0·03 % solution of basic dye in 5% aluminium sulphate produces a highly specific staining reaction for sulphated mucopolysaccharides. The best dyes are nuclear fast red (Herzberg) and methylene blue. Acid dyes in solutions of aluminium salts are induced to stain the ground substance of cartilage. These observations have been confirmed in a number of species.

Other metallic ions have similar properties and the use of green and purple chromic salts indicate that co-ordination plays a part in the reaction.

Methylation, saponification, and sulphation experiments show that the sulphate group is essential. This has been confirmed by using pure chemical substances in gelatin models. Oxidation of keratin with performic acid, which produces sulphonic groups, causes hair (previously negative) to react. From this it is suggested that sulphonic groups may also react, and that the reactive groups need not be attached to mucopolysaccharides. It is further suggested that the specificity of sulphated mucopolysaccharides is due to the fact that they are the only substances present in the tissues with a sufficient concentration of sulphate groups.

Experiments with solochrome azurine show that the aluminium is attached to all tissue elements irrespective of their nature. It is suggested by analogy with the work of others on the action of mordants that this attachment is by co-ordinate linkage.

Acid dyes of strong and weak type buffered to a variety of pH levels show that ionization plays little if any part in the staining of the sulphated elements, but may be of considerable importance in the staining reactions of the other tissue elements. By analogy with solochrome azurine, which is known to co-ordinate with aluminium, it is suggested that the dye is attached, by means of a further co-ordinate bond, to the metal. It is suggested that the sulphate group may owe its specificity to its strongly acid character, and the fact that such groups are capable of forming extremely stable complexes with metallic ions.

It is concluded that this is a highly specific method of staining sulphated mucopolysaccharides, depending upon the formation of a link by a metallic ion between the tissues and the dye, in the fashion of a true mordant. The ability of the dye to attach itself to the metallic ion depends finally upon the resultant of the electrostatic charges on the tissues and the metallic ion.
Experiments on the action of mordants 2. Aluminium-haematein
Authors: Baker John R.
Published: April 2021

Unmordanted haematein in aqueous solution varies in colour from yellowish orange at pH 3 to bluish magenta at pH 9.

In the presence of aluminium sulphate, the colour of solutions of haematein at any particular pH depends on the number of aluminium atoms to each molecule of haematein. At pH 4·6 the colour varies from yellowish orange through dull red to rose as the number of aluminium atoms to each molecule of haematein is increased from 12. The facts suggest that such solutions contain both uncombined haematein and an aluminium-haematein compound.

From about pH 5 upwards the aluminium-haematein compound is insoluble. Although the dominant colour is blue, a considerable proportion of red light is transmitted.

The blue colour attaches itself to tissue-constituents like a typical cationic (basic dye. It combines principally with the nucleic acids of chromatin; but if these are extracted from the tissues, it attaches itself to the acidic proteins of chromatin, and the appearance given is much the same.

In differentiation by acid, the mordant is set free from the tissue.

Chromatin that has been reddened by acid during or after dyeing becomes blue from about pH 5 upwards. Neutrality or alkalinity is not necessary for blueing.

The dull red aluminium-haematein compound present in acid solutions acts (like the blue) as a cationic dye.

When aluminium and haematein are used (as iron and haematein usually are) by the two-bath method, chromatin is dyed blue but collagen and certain other tissue-constituents yellowish. An exhaustive series of experiments shows that the yellowish colour is due to unmordanted haematein.

At room temperature haematein is about 17 times more soluble in ethylene glycol than in ethanol, and 21 times than in water. In 25% aqueous solution ethylene glycol is a suitable solvent for practical use. A solution in this solvent containing aluminium and haematein in the proportion of 8 atoms of the metal to one molecule of haematein may conveniently replace Mayer’s Hdmalaun and similar mixtures.
The fine structure produced in cells by primary fixatives.
Authors: Mercuric chloride I. , Baker John R. , Luke Barbara M.
Published: April 2021

The exocrine cells of the mouse pancreas were fixed in mercuric chloride solution, embedded in plexigum, and examined by electron microscopy. The cytoplasm was found to be coagulated as a continuous substance containing innumerable subspherical cavities, mostly between 40 and 200 mµ in diameter and separate from one another. The zymogen granules were preserved, but no trace remained of mitochondria or Golgi apparatus. The nuclear sap was coagulated as a coarse network with thickenings at the nodes. Lumps of electron-dense material (? DNA) were present at the periphery of the nucleus and round the nucleolus.

The proteins of the cell appear to have been fixed by mercuric chloride, but the membranous constituents, which rely for their form on a phospholipid component, are not clearly recognizable. The lipids have presumably been lost during dehydration and embedding.
On colouring epon-embedded tissue sections with Sudan black B or Nile blue A for light microscopy
Authors: McGee-Russell S. M. , Smale N. B.
Published: April 2021

Sections of osmium-fixed tissues embedded in epon 812 colour with either Sudan black B or Nile blue A solutions to reveal a variety of detail by direct microscopy with normal apochromatic or semi-apochromatic objectives. The clarity of the coloration gives a picture fully comparable to that seen by phase-contrast microscopy. The plastic is not removed. 1μ sections or thinner sections down to green or gold, are mounted on clean glass slides by drying down from 20% acetone/water after flattening on a hot plate. Colouring is carried out at room temperature in Sudan black B (saturated solution in 70% alcohol) for 1 to 2 h. The result is a reversed or negative effect, for the epon plastic takes the stain avidly, but dense elements of the tissue do not, and appear white against a blue background of stained plastic. Lipid droplets retain a capacity to colour, becoming dark blue to blue-black. Nile blue sulphate (1% aqueous solution) colours thin sections of tissue in 1 to 2 h at 60° C, acting apparently as a basic dye on most cell elements, and also colours lipid droplets dark blue. After both techniques the sections are mounted in Farrants’s medium.
The cytology of the digestive and salivary glands of the limpet, Patella
Authors: Pugh D.
Published: April 2021

As reported by earlier investigators, the epithelium of the digestive tubules is composed of two cell-types. One type of cell is glandular, the other type is absorptive and digestive, and to a lesser extent secretory. The latter type of cell also contains glycogen and numerous lipid globules, so that the digestive gland as a whole contains a large quantity of reserve food material. The epithelium of the digestive duct possesses a single cell-type ; the cells are ciliated and heavily pigmented, and they produce a viscous secretion.

The salivary gland is a compound tubular gland. The cells elaborate a secretion containing protein and probably some carbohydrate.
A study of the adrenal tissue of the male African bullfrog, Rana adspersa
Authors: Moorhouse Douglas E.
Published: April 2021

The structure of the adrenal tissue was investigated by both histological and histochemical techniques.

It is shown that the adrenal contains 4 types of tissues; these are named the steroid, Stilling, lymphoid, and chromaffin tissues.

The structure of the adrenal in the bullfrog does not provide any evidence to support a theory of zonation within the cortical tissue of the Anura, as suggested by some authors.

There is no alteration in the appearance or numbers of the ‘ summer cells’ of Stilling that can be correlated with the time of year or with the sexual activity of the animal. For this reason it is considered preferable to call these ‘ Stilling cells’, as was suggested by Magath (1915). There is evidence that structural differences are to be found between the Stilling cells and the granulocytes found in the lymphoid tissue.
Some observations concerning the supposed identity of the Golgi apparatus and Nissl substance of neurones
Authors: Thomas Owen Lewis
Published: April 2021

In nerve-cells the cytoplasmic inclusions commonly described as the Golgi apparatus are not identical with the basiphil Nissl substance.
Observations on the oxyntico-peptic cells in the proventricular mucosa of Gallus domesticus
Authors: Menzies Gordon , Fisk Alan
Published: April 2021

1.The cells described contain two types of granule. One type colours with Bowie’s technique, the other is Bowie-negative.

2.Both types of granule are Altmann-positive.

3.Neither type of granule is preceded by a PAS-positive granule during development.

4.The Bowie-positive granules are discharged after eating and after injection of pilocarpine or histamine.

5.There is no evidence that any of the Bowie-negative granules are discharged.

6.The cytoplasm in the cells is rich in RNA, but this is absent from the granules.

7.No intracellular canals are seen in the cells.

8.An infranuclear Golgi network is present after 3 days’ starvation. After feeding it changes its form and position and may become paranuclear. After injection of histamine or pilocarpine similar though more marked changes occur and the network in a few cells assumes a supranuclear position.

9.A line of granules that colour densely with Sudan black in a sudanophil ‘lake’ is present at the luminal border of the cells. It has not yet been possible to decide on their exact nature.
The fully formed intermoult cuticle and associated structures of Podura aquatica (Collembola)
Authors: Noble-Nesbitt J.
Published: April 2021

The cuticle overlying most of the body consists of 2 major layers only, the lamellate endocuticle and the epicuticle, and is very thin (1 to μ). Three major cuticular layers are found in the slightly thicker cuticle of certain areas (2 to 3 μ thick) and in the thickest regions (8 to 10μ)a distinct sclerotized exocuticle is present. The epicuticle consists of 1 to 4 laminae, the ‘inner’, ‘cuticulin’, ‘wax’, and ‘cement’ layers, and the distribution of these laminae is described. The outer surface of the cuticle is thrown into major tubercles of approximately 3 μ pitch, with minor tubercles super-imposed upon them. Modification of the cuticle at the bases of setae is described and related to the mechanical requirements of the setal insertion and suspension. The nature of the muscle insertion is also considered. The epidermis is fully cellular and the cells contain the granules of black pigment which impart the black coloration to the insect. Specializations of the epidermis in the regions of ocelli, setae, muscle insertions, and the vesicles of the ventral tube are described, along with modifications of the overlying cuticle.
Studies on the ovarian follicle cells of Drosophila
Authors: King R. C. , Koch Elizabeth A.
Published: April 2021

Studies are described of the ultrastructure of the follicle cells which invest the oocyte of Drosophila melanogaster at the time of vitelline membrane formation. Of particular interest are organelles made up of endoplasmic reticulum organized into a husk of concentric lamellae which surround lipidal droplets. These epithelial bodies are seen only at the time the vitelline membrane is being formed, and it is assumed therefore that the lipidal material of the epithelial body may be utilized somehow in the fabrication of the vitelline membrane. Cytochemical studies have shown this membrane to contain at least 5 classes of compounds; a protein, two lipids (which may be distinguished by differences in their resistance to extraction by various solvents), and 2 polysaccharides (1 neutral and 1 acidic). Studies were made of vitelline membrane formation in the ovaries of flies homozygous for either of 2 recessive, female-sterile genes (tiny and female sterile). In the case of the ty mutation vitelline membrane material is sometimes secreted between follicle and nurse cells, while in the mutant fes vitelline membrane is observed in rare instances to be secreted between follicle cells and an adjacent layer of tumour cells. In the latter case the vitelline membrane shows altered cytochemical properties. The fact that vitelline membrane can be secreted by follicle cells not adjacent to an oocyte demonstrates that it is the follicle cell rather than the oocyte that plays the major role in the secretion of the precursor material of the vitelline membrane. Subsequently the follicle cells secrete the egg-shell, or chorion, which is subdivided into a dense, compartmented, inner endochorion, and a pale, outer exo-chorion. A description is given of the ultrastructure of the follicle cells during the secretion of the endochorion and the exochorion. The endochorion contains a protein, a polysaccharide, and a lipid, all of which may be distinguished cytochemically from the vitelline membrane compounds. The exochorion contains large amounts of acidic mucopolysaccharides. Specialized follicle cells form the micropylar apparatus and the chorionic appendages. The formation of the chorion and chorionic appendages is discussed in the light of information gained from abnormalities of the chorions and chorionic appendages seen in ty and/s 2-1 oocytes. Subsequent to the time the egg leaves the ovariole a layer of waterproofing wax is secreted between the vitelline membrane and the chorion.
A histological study of the peripheral receptors in the thorax of land isopods, with special reference to the location of possible hygroreceptors
Authors: Jans D. E. , Ross K. F. A.
Published: April 2021

By double embedding whole isopods in paraffin wax and celloidin, after fixing them in Bodian’s fluid, it was possible to obtain complete sets of undamaged serial sections through the thoracic and abdominal regions of females of Oniscus asellus L. and Porcellio scaber Latr., and also some incomplete series through males of these species and a species of the genus Armadillidium. These sections were stained by the methods of Bodian and of Holmes to show the nerve-fibres. They were then carefully studied, and the distribution and the morphology of all peripheral nerve-endings and receptors in the body were determined as completely as possible.

In all, 6 different types of terminations were found; and in some cases it was possible to draw valid inferences about their probable function from a consideration of their location and their morphology alone. Three of them are probably tactile. The function of the other three is much more uncertain; but one of them, a group of pit-like terminations situated on the under side of the lateral plates on each side of the thoracic segments, is particularly suitably located to function as a receptor of temperature or humidity, and morphologically it bears some resemblance to certain proven hygroreceptors in other arthropods. This particular termination and one of the other types, consisting of ventrally situated partially retracted hairs, do not appear to have been described previously in the land isopods.
The vital staining of Amoeba proteus
Authors: Byrne Jennifer M.
Published: April 2021

The effect of keeping Amoeba proteus in dilute basic dye solutions was studied. It was found that Nile blue, neutral red, and neutral violet in particular, and also brilliant cresyl blue, methylene blue, Bismarck brown, thionin, toluidine blue, and azures A and B act as vital dyes, while at comparable molarities crystal violet, dahlia, safranin, methyl green, Janus green, and Victoria blue are lethal, and do not produce any stain-ing until after death. Azure C, basic fuchsin, and particularly pyronine G are relatively harmless, but produce no vital staining.

All the vital dyes stain the food vacuoles, and all produce small, darkly stained granules in colourless vacuoles in the cytoplasm. The latter do not exist in the unstained amoeba. Some of the dyes colour vacuoles around the crystals. These crystal vacuoles also seem to be induced. A few of the dyes colour the spherical refractive bodies, which are at least in part phospholipid.

All the basic dyes used with the possible exception of azure C, methyl green, and pyronine G attach to the external membrane of A. proteus in an orientated manner, as shown by the increase in birefringence of the external membrane induced by these dyes. It is particularly those dyes that act as vital dyes that produce a very pronounced increase in the birefringence of the external membrane.
The sense organs on the antennal flagellum of aphids (Homoptera), with special reference to the plate organs
Authors: Slifer Eleanor H. , Sekhon Sant S. , Lees A. D.
Published: April 2021

The cuticular parts of the aphid plate organ consist of an outer and an inner layer. Both are transparent and in the space between them are many fine branches of the half dozen, or more, sensory neurones which lie below the plate. Each dendrite narrows, a short distance above its cell body, and assumes the structure of a cilium with 9 pairs of peripheral fibrils, a ciliary collar, and basal bodies with rootlets. Distally the dendrite loses its ciliary structure, passes through one of several openings in the inner cuticular layer of the plate and branches repeatedly. The only formed cytoplasmic elements so far identified within the branches of the dendrites are neurofilaments. The outer cuticular layer of the plate is perforated by a large number of small openings. Groups of filaments leave the surface of the dendrite branches and enter these openings. The filaments have a diameter close to 10 mμ and resemble the neurofilaments within the dendrite branches.
‘Chloride cells’ in the gills of fresh-water teleosts
Authors: Datta Munshi J. S.
Published: April 2021

Specialized cells of several kinds, namely, (a) mucous-gland cells, (b) large bior tri” nucleate glandular cells, and (c) mast cells occur in the gills of some species of freshwater teleosts.

The typical ‘goblet’ type of mucous glands are present in large number in freshwater species, such as Catla catla, Labeo rohita, Ophiocephalus punctatus, and Mastacembalus armatus. In Catla catla, these glands respond to the ‘chloride test’. This indicates that, besides discharging mucus, they also play some part in the elimination of chloride. In Ophiocephalus punctatus, Ciarias batrachus, and Heteropneustes fossilis only some of the mucous cells give a positive reaction with the AgNO3/HNO3 test for chloride. This may mean that a few of them are in a state of active secretion of chlorides, while others are in a non-secretory phase.

Large eosinophil glands with 2 or 3 nuclei also occur, chiefly in the siluroids. The function of these hypertrophied multicellular glands is not clear.

Judged by the AgNO3/HNO3 test, Catla catla possesses the highest number of chloride cells. In Hilsa ilisha, Rita rita, Ophiocephalus striatus and Mastacembalus armatus, only a ‘network of silver’ exists on the surface of the primary and secondary lamellae.

The ‘chloride cells’ are said to be a characteristic of marine fishes in which an extrarenal mechanism for the elimination of excess of salts from the body fluid is necessary for correct osmo-regulation. These cells are also said to make their appearance in fresh-water fishes that have been experimentally subjected to a saline medium. The presence and occurrence of ‘chloride cells’ in fresh-water fishes living in their natural habitat is, therefore, interesting. The discovery of the presence of actively secreting chloride cells in certain species of fresh-water teleosts and their mucoid nature are new results reported here.
The histochemistry of the saccus vasculosos of Notopterus chitala (Teleostei)
Authors: Sundararaj Bangalore I. , Prasad M. R. N.
Published: April 2021

The saccus vasculosus of Notopterus chitala is situated posteriorly to the pituitary gland. It consists of a number of loculi surrounded by blood sinusoids. The loculi open into a number of collecting channels which unite and ultimately drain into the third ventricle of the brain. The loculi are lined by a layer of pear-shaped ‘coronet cells’. The coronet cell has an apical protrusion provided with hairs, each ending in a globule. The coronet cells contain glycogen, especially in the apical protrusions and in the globules. Phospholipid, alkaline phosphatase, and mitochondria are concentrated in the apical protrusion and globules. There are also mitochondria round the nucleus. The Golgi element is not only present in the characteristic Golgi zone but occasionally round the nucleus as well. It has been stated by other authors that acid mucopolysaccharides are synthesized in the coronet cells of the rainbow trout and ‘secreted’ into the lumen of saccus vasculosus. However, acid mucopolysaccharides are not histochemically demonstrable in the coronet cells of Notopterus. The observations recorded in this paper indicate that the coronet cells in the saccus vasculosus of Notopterus are secretory and that glycogen is abundant in them.
Neurociliary synapses in Pleurobrachia (Ctenophora)
Authors: Horridge G. A. , Mackay B.
Published: April 2021

Synapses of a typical form, with synaptic vesicles of 30 to 45 mµ diameter, on one side of a synaptic cleft of 10 to 12 mµ, are found near the bases of the long ciliated cells which make up the comb plates. The side containing the vesicles is interpreted as a section of a nerve fibre terminal in contact with the ciliated cell. Occasionally nerve-cell bodies, identified by similar vesicles, are encountered. These nerves are probably ramifications of the ectodermal nerve net which spreads over the whole animal and which transmits the inhibition of the ciliary waves when the animal is touched. Distinctly different nerve fibres, which run from the apical organ along the ciliated grooves to the end of the comb rows, are able to initiate a ciliary wave along the comb row. The excitatory nerves appear as rather empty axons which mingle with the bases of the ciliated cells. The question of the propagation of excitation between these axons, between the ciliated cells of a comb plate, and between comb plates, remains open, although regions where excitatory axons and ciliated cells make contacts between themselves and with each other have some resemblance to electrically transmitting synapses.
Observations on the nervous system of the flight apparatus in the locust Schistocerca gregaria
Authors: Guthrie D. M.
Published: April 2021

The hair sense-organs of the head are part of a sensory system affecting the activity of motor neurones to the flight muscles. They possess curved hollow hair shafts inserted in a complex socket. A large neurone is present beneath the socket and is partly surrounded by a large formative cell, the trichogen-tormogen cell. The distal process passes up into the expanded base of the hair shaft. Fine connexions between the outer region of the formative cell and the inner part round the neurone process, possibly limiting angular sensitivity, can be seen in some specimens, although the form and fine structure of the hair shaft is almost certainly important in this respect.

The axons from the 5 areas of hair organs are collected together into a dorsal tegumentary nerve, those from area three forming a short subocellar nerve. Electronmicrographs of this nerve show that there are a number of large fibres (1 to 5 μ), and many more smaller fibres (1· to 0·1 μ) with no sheaths. There were estimated to be 5,500 fibres in each dorsal tegumentary nerve.

Within the central nervous system, the dorsal tegumentary fibres may follow one of 4 routes, as follows. They may (i) pass forward into the protocerebrum, (ii) end in zones of terminals in the deutocerebral region, (iii) a few thick fibres pass down into the suboesophageal ganglion and then cross over to the opposite side giving off collaterals before descending to the pterothoracic ganglia, (iv) most of the fine descending fibres probably end at the suboesophageal level, a proportion of them crossing over here.

The motor neurones to the longitudinal indirect muscles M81 and M82 consist of 4 anterior and 1 posterior cell respectively, and possess large and striking cell bodies, whose collaterals could be seen in the dorsal zones of motor terminals. The probable internuncial links between the sensory and motor arcs are outlined.
An electron microscopical study of neutral red granules in mouse exocrine pancreas
Authors: Byrne Jennifer M.
Published: April 2021

The neutral red granule cycle in the mouse exocrine pancreas was studied with the electron microscope in order to discover what changes appear at an ultrastructural level in cells treated with neutral red.

There are no changes in the endoplasmic reticulum, the nucleus, the Golgi apparatus, the zymogen granules, or the mitochondria of stained cells when compared with normal tissue. Osmiophil inclusions are found which in their size and distribution correspond to the neutral red granules seen under the light microscope. Such inclusions are not seen in normal tissue. They resemble morphologically the lysosomes of various tissues.
Observations on the development of certain cell types in the fundic region of the rabbit’s stomach
Authors: Menzies Gordon
Published: April 2021

Pre-oxyntic cells, arising from a non-mucoid cell, appear on the 20th or 21st day of foetal life. Cells of Twort appear first at the end of the 4th week after birth. Combined oxyntico-peptic cells are occasionally found in the 2nd, 3rd, and 4th weeks after birth. Another type of cell, demonstrated by Wigglesworth’s method, is found in the 4th week after birth.
Localization of a bound lipid fraction in the pancreas of the mouse
Authors: MAGGI VIVIANE , CARBONELL A. W.
Published: April 2021

The pancreas of adult and old mice of various ages has been shown to contain a lipid fraction which is not normally stainable, but which is unmasked by the action of the lipid-solvent methanol : chloroform (1:2 v/v) and hence becomes stainable by the acid haematein reaction. This fraction seems to be contained in the zymogen granules of adult and old mice, but is absent from the pancreas of 1- to 2-week-old animals.
Circadian organization of chitin in some insect skeletons
Authors: Neville A. C.
Published: April 2021

A circadian clock is shown to be involved in the control of macromolecular orientation of chitin by cells secreting and organizing insect endocuticle. Daily organization of locust endocuticle into alternating lamellate and non-lamellate layers persists in constant temperature (36 ° C) and constant darkness for at least 2 weeks; the freerunning period is then about 23 h, so that after a number of days the circadian clock is 180° out of phase with the astronomical clock, with which it is normally phased. The rhythm is almost independent of temperature, with a Q10 of 1·04, as contrasted with a Q10 of 2·0 for the actual rate of increase of endocuticular thickness. Locust epidermal cells differ in response to specific imposed environmental conditions according to their location in the integument. In some cells, constant low temperature uncouples chitin lamellogenesis from the circadian clock, provided that illumination (light or dark) is constant also: the result is continuously lamellate endocuticle. In other cells constant light acts as an uncoupling factor, provided that temperature (high or low) is constant also: the result in this case is continuously non-lamellate endocuticle.

The circadian rhythm of chitin lamellogenesis persists in a cave cricket (Dolichopoda linderi). A similar circadian lamellogenesis rhythm occurs in the endocuticle of nymphs and adults of the cockroach Periplaneta americana. A crossed-fibre multiple-ply endocuticle in the legs and wings of giant toe-biter water bugs (Belostomatidae) also displays circadian organization, the chitin macromolecules in any one layer lying in parallel fibres, at an angle of approximately 60° to those in the next layer.

It is suggested that daily organization of the skeleton may be a general feature of arthropods. Examples include the phenomena of timing of chitin lamellogenesis; chitin crossed-fibrillar organization; degree of fluorescence of the rubber-like protein resilin; and mineralization of crayfish gastroliths.
Some Observations with the Phase-contrast Microscope on the Neurones of Helix aspersa
Authors: Thomas Owen Lewis
Published: April 2021

Although various investigations have contributed to the development of phase-contrast microscopy from the time of Abbe, the production of a completed microscope available for use in biological and allied fields has been a comparatively recent achievement (Köhler and Loos, 1941). A good review of this promising advance is given by Bennett (1946).

The neurones of Helix aspersa have been chosen for the present study as these cells are large and easily isolated in a fresh state, as well as for their having already been the subject of a number of cytological investigations (Kolatchev, 1916; Brambell, 1923; Brambell and Gatenby, 1923; Boyle, 1937). The following observations are limited to a description of the appearance of the neurofibrils in these cells together with a description of some very small particles shown to be present in their protoplasm, distinct from and of a much smaller order than the mitochondria. A further communication is on hand concerning some observations on the other inclusions and organoids of these cells.
Growth and Regeneration in the Tracheal System of an Insect, Rhodnius prolixus (Hemiptera)
Authors: Wigglesworth V. B.
Published: April 2021

The tracheoles in Rhodnius are simple or branched tubes, usually 200–350 μ in length, each formed within a single cell, the nucleus of which lies at about 75 μ from the point of origin. They taper gradually from a diameter of 0·7–0·8 μ to end blindly at about 0·2 μ.

Once laid down the tracheoles persist unchanged throughout the life of the insect; unlike the tracheae they do not shed their lining cuticle at moulting (cf. Keister on Sciara). New tracheae and tracheoles arise by the outgrowth of columns of cells from the sides or endings of existing tracheae at the time of moulting.

The tips of the tracheoles migrate actively towards regions of deficient oxygenation, drawing the tracheae after them. Movements up to one millimetre have been observed. This is the mechanism by which implanted organs are provided with a tracheal supply in the absence of moulting.

The outgrowth of new tracheae and tracheoles is greatly stimulated in regions of deficient oxygenation. This is the mechanism of ‘tracheation’ of implanted organs when moulting takes place.

If the insect is reared in reduced concentrations of oxygen, there is an increase in the number of large tracheae developed. This is particularly evident in the wing lobes. The general pattern of wing venation is not affected by this altered tracheal arrangement, but minor changes may occur. These are briefly discussed.
A Technique for the histochemical demonstration of polyphenol oxidase and its application to egg-shell formation in helminths and byssus formation in mytilus
Authors: Smyth J. D.
Published: April 2021

The distribution of polyphenol oxidase in quinone-tanning systems may be demonstrated in frozen-dried sections by incubation in 0·2 per cent, aqueous catechol at 40° C. for 15–60 minutes. A red colour develops at the enzyme site. The evidence for the view that the egg-shell in trematodes, in certain cestode groups, and in turbellarians, is a quinone-tanned protein secreted by the so-called ‘vitelline’ glands, is summarized. The ‘vitelline’ cells, in addition to giving positive reactions for proteins and phenols, give a strongly positive reaction with the catechol polyphenol oxidase test. The catechol technique may also be applied to whole helminths fixed in 70 per cent, alcohol, and serves as a useful whole mount stain for the shell-producing regions of the female genitalia. In Mytilus the catechol technique reveals the presence of polyphenol oxidase in an ‘upper’ or enzyme gland in the foot. It is suggested that in Mytilus the byssus is formed from a phenolic protein secreted from the phenol gland, which on contact with polyphenol oxidase can undergo ‘auto-quinone tanning’.