bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Histology and Regeneration of the Teleost Scale
Authors: Neave Ferris
Published: April 2021

The Teleost scale, as typified in the goldfish, is covered intimately by two layers of cells on the external surface.

The internal surface of the young scale is invested with a cell layer which is continuous with the deeper external layer. These cells may be regarded as osteoblasts and osteocytes and are concerned with the formation of the outer bony portion of the scale.

In the development of regenerate scales, osteoblasts pass from the periphery of the scale pocket to the growing edge of the scale. The latter consists at first of osteoid tissue, which later becomes calcified.

The fibrillary plate is at first collagenous but apparently becomes infiltrated with ichthylepidin after being laid down.

The scale is wholly mesodermal in its tissue relationships.

The ridges of the scale are formed between cell rows of the deeper external cell layer. They are not the product of specific cells. Ridge formation probably depends on the presence of boneforming materials in the intercellular fluid in amounts greater than can be utilized at the growing margin. These are deposited between cells in the vicinity.

The sulci of ontogenetic scales represent lines of flexibility. This condition is attained not only by the absence of the bony layer but by a special condition of the underlying fibrillary plate, which apparently does not become impregnated with ichthylepidin beneath the grooves.

Regenerate scales may be monocentric, in which case a relatively large central area is devoid of ridges. Absence of ridges is interpreted as due to the utilization of all available scaleforming material at the growing margin. The size of the central area does not correspond to the size of the original scale. In the goldfish the regenerate scale is commonly polycentric, the bony portion developing from more or less numerous growth centres whose ultimate margins are indicated by grooves similar to the sulci of ontogenetic scales. The number of growth centres depends in a general way on the space available. The fibrillary plate is continuous beneath the bony islets but remains flexible beneath the grooves.

Three processes contribute to the re-scaling of areas from which scales and pockets have been removed: (1) enlargement of ontogenetic scales at the margin of the wound area, (2) regeneration of scales in partially destroyed pockets at the margin of the wound area, (3) development of new scales within the wound area.

New and regenerate scales always develop in the vicinity of pre-existing scales or papillae, under the influence of specific osteogenic cells which do not arise de novo from the corium.
The Structure and Function of the Alimentary Canal of Aplysia Punctata.
Authors: H. Howells H.
Published: April 2021

1. The anatomy and histology of the alimentary canal, process of feeding, and physiology of digestion in Aplysia punctata have been investigated.

2. The food undergoes little trituration in the buccal cavity. The mode of action of the jaws and odontophore is adapted to the rapid intake of vegetable food.

3. The oesophagus and crop together form an anatomical and physiological unit.

4. Trituration occurs in the gizzard. The teeth are adapted to the trituration of plant material ; this is of particular importance owing to the weak action of the cellulase.

5. Coarser particles of weed are retained by the teeth of the filter chamber and returned to the gizzard during the forward movement of the gut fluid.

6. The ciliary currents in the anterior intestine ensure that only food in a finely divided or fluid state is admitted to the stomach. Medium and larger sized particles are carried straight into the intestine.

7. Ciliary currents in the stomach are concerned with the removal of material rejected from the tubules of the digestive diverticula. This material is consolidated, cemented, and moulded into a faecal rod within the caecum, and conveyed by ciliary action to the intestine.

8. The intestine is concerned with the further consolidation and moulding of the complete faecal mass, and its propulsion (by combined ciliary and muscular action) to the rectum.

9. Mucus is secreted throughout the gut with the exception of the regions of the jaws, gizzard, and filter chamber. Enzymes are secreted in the salivary glands (amylase and protease) and in the digestive diverticula (carbohydrases, lipase, and proteases). Glands probably secreting a lubricant (other than mucus) occur in the epithelium of the lateral walls of the buccal cavity, and others, secreting a cementing substance, in the caecum and intestine.

10. Absorptive cells occupy the greater part of the epithelium of the digestive diverticula. They occur together with secretory, excretory, and storage cells.

11. Digestion occurs within the oesophagus and crop, gizzard, filter chamber, anterior intestine, stomach, and tubules of the digestive diverticula. The hydrogen ion concentration is here suitable for the action of the enzymes, and the gut fluid is kept in motion by the muscular activity of the walls.

12. A high pH exists in the lumen of the caecum, posterior intestine, and rectum, probably assisting in the consolidation of the faecal mass by increasing the viscosity of the mucus.

13. The presence of a highly efficient mechanism for the formation of the faeces is probably correlated with the poorly developed cleansing mechanism in the mantle cavity.
The Free Border of the Intestinal Epithelial Cell of Vertebrates
Authors: Baker John R.
Published: April 2021

The structure of the free border of the epithelial cells of the intestine has been investigated in various adult and larval Amphibia and in a reptile, bird, and mammal. The structure is essentially the same in all (except in frogtadpoles in the stage with external gills). This structure is shown diagrammatically in Text-figs. 1 and 2. The free border consists essentially of three layers: A superficial layer, pierced by pores, next the lumen of the intestine. A canal layer, pierced by spindle-shaped canals continuous with the pores of the superficial layer. These canals traverse the layer at right angles to its surface. A granular layer, containing many spherical granules, next the cytoplasm of the cell. The intercellular band or Kittleiste is situated at the level the granular layer. The continuous substance of the canal layer—that is, the substance that intervenes between the canals—appears to be composed of proteins. The granular layer contains lipines. The theory that the free border contains ‘rods’ is found to be erroneous. It is suggested that unhydrolysed fats may enter the intestinal epithelial cell through the pores and canals in the form of extremely fine droplets. Two hypotheses are put forward, the one mechanical and the other electro-endosmotic, to account for the passage of substances from the cavity of the intestine into the epithelial cells.
The Development of the Olfactory Organ of Kaloula borealis (Barbour) as compared with that of Rana nigromaoulata Hallowell
Authors: Tsui Chi-Lan , Pan Tsing-Hwa
Published: April 2021

IN a previous paper on the development of the olfactory organ in Rana nigromaoulata by one of the present authors (Tsui, 1946a) questions were raised about the significance of the ephemeral existence of the lateral appendix and about the functions of different kinds of nasal glands and of Jacobson’s organ or the recessus medialis. To elucidate them experimental studies will be necessary. Unfortunately the species nigromaoulata which is abundant in North China is very rare in this part of the country. Kaloula borealis, on the other hand, is very common here. In order to use it as experimental material, familiarity with the developmental history of its nasal organ is prerequisite. In addition, it is of interest to compare the development of this organ in Bana nigromaoulata and Kaloula borealis, and to see whether certain findings in the former species concerning certain controversial points will be confirmed in the latter.
New Observations upon the Minute Anatomy of the Papillæ of the Frog’S Tongue
Authors: Beale Lionel S.
Published: April 2021

In this paper I propose to give the results of some recent investigations upon the minute anatomy of the beautiful fungiform papillae of the tongue of the little green tree-frog (Hyla arbórea). The specimens have been prepared according to the principles laid down in former communications. The success I have met with in this and other minute anatomical inquiries is, I believe, almost entirely due to the process of investigation which I have adopted for some years past, and which enables me to render specimens very transparent, and to demonstrate all the tissues in one specimen, a result which, as far as I am aware, can be obtained in no other way. By this plan sections are obtained so exceedingly thin, without the destruction even of the most delicate tissues, that they maybe examined under the highest powers which it is possible to obtain magnifying 1700 linear, and magnifying about 3000 linear).
On the Colouring Matters of Blue Decayed Wood
Authors: Sorby H. C.
Published: April 2021

Decayed wood, coloured blue by the spawn of Peziza œrugnosa (see ‘Quart. Journ. of Science/V, 222) contains several colouring matters. None of these are sensibly soluble in water, but they are dissolved by alcohol with varying facility, so that they may be separated with a little care. On digesting with the aid of heat a portion of the wood in a moderate quantity of alcohol, a solution of dull neutral tint is obtained, and the wood is left of a bluer green. On agitating the alcoholic solution with bisulphide of carbon, that liquid abstracts a small quantity of a yellow colour, which does not present any facts of particular interest. The alcoholic solution is a mixture of a claret colour, very easily dissolved by alcohol, and a blue, soluble with much greater difficulty, so that, on evaporating to dryness and redissolving in a little alcohol, the blue colour is left and the claret dissolved, which may be still further purified by evaporating to dryness and redissolving a second time. It is then of a decided claret colour, with no trace of blue or green, and the spectrum shows a strong absorption at the blue end, gradually becoming less towards the red. Adopting the scale and nomenclature described in my paper in the ‘ Proceedings of the Royal Society/1 the spectrum is about 3 9 11 —. The addition of a little ammonia turns it green, and develops an absorption band in the orange, the centre being at 3. Citric acid restores it to the original state, unless so much ammonia has been added as to produce decomposition. Sulphite of soda has no effect on an acid solution, so that the colour may be described as C alo am, (3). I have not yet met with such a colour in any other substance.
On the Epithelium of the Cobnea of the Ox.
Authors: Cleland John
Published: April 2021

It is well known that there are many appearances in stratified epithelia not easily explained by that simplest theory of their growth which is naturally first suggested, and is no doubt in all instances partially true -, namely, that cells originating in a deep position pass gradually to the surface as they grow and alter in figure, while those superficial to them are cast or dissolved, and others behind them follow in their steps. Thus the elliptic cells in the deeper strata of the epithelium of the trachea can scarcely be supposed to be developed into the ciliated columns which lie over them ; and it cannot be imagined that in the ureter the large and irregularly shaped cells are altered so as to form the smaller and flatter cells found on the surface.
Description of a Species of Trematode from the Indian Elephant, with Remarks on its Affinities
Authors: Cobbold T. Spencer
Published: April 2021

On the 24th of June of the present year I received a small bottle containing two flukes. It was accompanied by a note from Dr. Baird, F.R.S., stating that the specimens had been transmitted to him from India by Dr. Hugh Cleghorn. On the phial itself was a brief notice to the following effect :— Distoma taken from Liver of Elephant at Rangoon, forwarded for classification to Professor Cobbold by Vet.-Surgeon J. Thacker. Madras Army.” This is all I know of the history of these two entozoa. On naked-eye inspection it was clear to me that they were identical in character with a larger series of specimens previously exhibited by Professor Huxley during the delivery of a recent course of lectures at the Royal College of Surgeons. Having communicated to Professor Huxley the facts as above stated, I received permission to make use of his set of specimens, originally fifteen in number, for the purposes of comparison and description. This series was placed in Mr. Flower’s hands last February, and six of the individuals were subsequently selected and mounted, with the view to their being added to the valuable collection of entozoa contained in the Hunterian Museum.
Enumeration of Micro-Lichens parasitic on other Lichens
Authors: Lindsay W. Lauder
Published: April 2021

The Lichens to which the present communication refers constitute an increasingly large and important group—for the most part of athalline forms—whose apothecia (with or without spermogonia or pycnidia) alone represent the plant : minute in size, frequently obscure and difficult of observa-tion, requiring for the determination of their structure and place in classification the patient use of the microscope. 1 The group is a most heterogeneous one, comprising many genera and species that are at least anomalous: 3 that have been imperfectly studied : and that are comparatively little known. There are several advantages, I think, from bringing them together and studying them in a group. I believe that a satisfactory study will result in a great reduction of their generic and specific names. The present names— —generic especially—must be considered as only provisional. As matters stand, different names are probably given to the same parasite as it grows on different Lichens. It will be found, moreover, I doubt not, that the number of Lichens of the lower groups (e. g. in the single genus Lecidea, or its numerous and varied sections or sub-genera) which occur in an athalline parasitic form are more numerous than we at present suppose.
On Naked Fresh-Water Radiolaria
Authors: Focke Dr. Gustav Woldemer
Published: April 2021

The distribution of animals in the older strata of the earth’s crust would lead one to assume that fresh-water lakes could not have been inhabited until a late period, and, indeed,’’the distribution of living beings in fresh and salt waters is now very disproportionate. With regard to many orders of the animal kingdom, nature seems to have made some feeble attempts to populate fresh waters, and then to have given up the matter ; with others the distribution in both quarters is tolerably equal, although no very important physiological differences seem to exist; with the majority the sea presents a most decided predominance. Until recently Radiolaria have been found only in the sea, or at least shell-less free-living forms have never yet been observed in fresh water. In the middle of last summer I, to my great surprise, discovered at the same source · three different kinds of creatures which presented decided characters of Radiolaria. As most of the inhabitants of the sea belonging to this order are enclosed in hard porous shells, the examination of their tissue elements is rendered difficult to a great degree ; consequently, the opportunity of examining these free-living forms from fresh water offer a very desirable facility for making a minute investigation.
On Raphides, SphæRaphides, and Crystal Prisms ; Especially as to how and where they may be easiest found and discriminated.
Authors: Gulliver George
Published: April 2021

What are the distinctive characters of raphides, sphæ- raphides, and crystal prisms ? How may they be surest and easiest found, and in what common plants ? Is not the occurrence of raphides very inconstant, seeing that either their presence or absence in one and the same plant is alternately affirmed and denied, and that they are not always found in those very species or classes, such as the “tulipbulb “and “monocyteledons generally,” in which we are directed to look for them ?
On Some Freshwater Rhizopoua, New or Little-known.
Authors: Archer William
Published: April 2021

The microscopist, in the course of his examination of his gatherings made from pools and ditches, be the objects of his research what they may, cannot fail to encounter certain ordinary representatives of the group, to some new or little- known forms of which, I am, in the following communication, very cursorily about to draw attention ; and this, indeed, rather by hardly more than simply pointing to the figures, than by assuming to throw upon them an additional light by any special observations.
An Examination of the Cuticles of two Scorpions, Pandinus imperator and Scorpiops hardwickii
Authors: Kennaugh J.
Published: April 2021

The cuticles of Pandinus imperator and Scorpiops hardwickii have been examined histologically and histochemically. They consist of a two-layered epicuticle, a hyaline exocuticle, a quinone-tanned exocuticle, an impregnated but untanned exocuticle, and on the inner surface an unmodified procuticle. The hyaline exocuticle is, however, single in Scorpiops and double in Pandinus. With the exception of the hyaline exocuticle the cuticles therefore conform to the basic arthropod pattern.

The quinone-tanned exocuticle closely corresponds with that of insects but the hyaline exocuticle seems to have no counterpart in other arthropods. The sulphur content of the cuticle has been determined and it is probable that sulphur is present only in the hyaline exocuticle.

The statement by Krishnan that chitin is present in the epicuticle is critically examined and a possible explanation of the differences which have been reported between the cuticles of different scorpions is offered.
The Iron-containing Shell of Gromia oviformis (Rhizopoda)
Authors: Hedley R. H.
Published: April 2021

Gromia oviformis has an organic shell or wall modified at one point to form a specialized oral region through which the protoplasm extrudes as pseudopodia. Whereas the shell appears to be predominantly proteinaceous with additional acid mucopolysaccharide and lipid components, the gel-like oral capsule, the main feature of the oral region, appears to be composed mainly of acid mucopolysaccharide.

The changes in form undergone by the oral capsule during the opening and closing of the oral region are described.

The shell, apart from the oral capsule, normally contains a large amount of ferric iron. When sections, from which the iron had been removed, were immersed in seawater reinforced with iron or in aqueous iron solutions, it was found that iron was only taken up by the shell when the concentration was greater than 12·5 mg Fe per litre. Only when the concentration was in the region of 200 mg Fe per-litre did the shell take up an amount comparable with that which is normally present. It appears unlikely that during life a reaction between the iron in normal sea-water and the shell can be wholly responsible for the iron content of the organic wall. Alternative sources of iron are discussed.

A great reduction in the amount of iron taken up from iron solutions under conditions of low pH, and after the sections have been methylated, points to the importance of carboxyl groups in the binding of iron by the shell. The nature of the union of the iron with the wall is discussed and shown to be similar in some ways to that in leather tanning processes where inorganic tanning agents are employed.
The Test of the Ascidian, Phallusia mammillata
Authors: Endean R.
Published: April 2021

A mucopolysaccharide, readily removed by mild acid hydrolysis, is associated with cellulose in the test of Phallusia mammillata (Cuvier). The mucopolysaccharide is produced in the vacuolated cytoplasm of epidermal cells covering the blood-vessels of the test.

The cellulose of the test appears to be produced by vanadocytes which have migrated into the test matrix through the walls of the test blood-vessels. In the test, the vanadocytes lose their acid and intraglobular osmiophil material and produce processes which extend into the surrounding test matrix. Minute globules and submicroscopic vesicles are present in the cytoplasm surrounding the large polysaccharide-containing globules of such vanadocytes, and also in the processes arising from such cells. The small globules and vesicles appear to arise from the large globules and to be involved in the production of micro-fibrils observed in electron micrographs of the test. The micro-fibrils, which vary from 20 to 40 m/x in diameter and are arranged in the form of an open network, may constitute a cellulose framework within the test.

An area devoid of test matrix occurs usually near each disintegrating vanadocyte. The remnants of each vanadocyte often come to lie in such an area. Capsules—the so-called ‘bladder cells’ of the test are thereby formed.

Phagocytes occur throughout the test and melanin-containing pigment cells are aggregated around its periphery.
The Structure and Function of the Cutaneous Glands in Helix aspersa
Authors: Campion Mary
Published: April 2021

The glands discharging ‘slime’ on to the surface of the mantle collar and foot of Helix aspersa have been investigated histologically and histochemically on chemically fixed and frozen-dried material.

All the glands are unicellular; they lie in the connective tissue and discharge by pores passing between the epidermal cells; some are club-shaped, others are polygonal with a distinct and usually long duct. At least 8 different kinds of gland are found: 4 extruding various kinds of mucus, one protein, one calcium carbonate granules, one a pigmented secretion containing a flavone, and one releasing fatglobules. The histology of the mantle collar is very similar to that of the dorsal and lateral surfaces of the foot except that the glands in the mantle are usually larger.

All kinds of secretion are extruded from these parts. The glands of the sole of the foot are mostly of a distinct kind and produce mucus combined with protein.

The mechanism of discharge is discussed: some of the gland cells are enclosed in a network of muscle-fibres which are thought to be concerned in the removal of the secretion, in other cases no fibres have been found and it seems likely that changes in pressure in the haemocoel are involved.

The composition of the slime changes from colourless and viscous to yellow and watery when the animal is irritated. It is usually slightly alkaline, is not distasteful to man, and does not inhibit the growth of micro-organisms. The mucous component acts as a lubricant, and on the sole for adhesion. The calcium carbonate granules and the protein may be concerned in defence, while the flavone is a waste-product varying with the amount of green food eaten.

The epiphragm is formed by the secretion of part of the mantle collar and is probably dissolved away by a protein-splitting enzyme which has been demonstrated in the slime.
An electron microscope study of the tegument and associated structures of Dipylidium Caninum
Authors: Threadgold L. T.
Published: April 2021

The ultrastructure of the ‘cuticle’ of Dipylidium caninum is described. The presence of mitochondria within the ‘cuticle’ and the connexion between it and subcuticular cells indicates that the outer covering of this cestode is of living cells forming an epidermis. On its external surface the epidermis is folded into finger-like micro-thriches and its thickness is pierced in places by pore-canals ending at the basement membrane. The sunken epidermal cells contain mitochondria, endoplasmic reticulum, fatty or glycogen inclusions, and protein crystalloids. It is suggested that such cells act as both storage and synthesizing units.

The possible bearing of the present morphological findings on cestode physiology is discussed, especially in reference to cestode resistance to digestion and the ability of the ‘cuticle’ to absorb.
The demonstration of lysosomes by the controlled temperature freezing-sectioning method
Authors: Bitensky Lucille
Published: April 2021

Lysosomes, as isolated and defined by biochemists, are particles in which acid lytic enzymes are contained by a lipoprotein membrane; they are inert until the membrane has been rendered permeable. Previously it has not been possible to demonstrate cyto-chemically organelles which meet all these criteria, since all the preparatory procedures have affected the membrane permeability. The controlled temperature freezingsectioning method has permitted the demonstration of granules which are inactive for acid phosphatase until subjected to agents that will disrupt lipid-protein structures, such as heat, formalin, and ‘triton X-100’. Hence such organelles may be identified with the biochemists’ lysosomes.
Studies on the receptors in the cerebral vesicle of the ascidian tadpole, I. The otolith
Authors: Dilly P. N.
Published: April 2021

Electron microscope observations of the gravity receptor of the tadpole larva of Ciona intestinalis show that the otolith is unicellular. The nucleus of the otolith persists for the entire life of the tadpole. The pigment mass of the otolith is intracellular, and it appears to be built up by fusion of granules. The otolith cell has a free part within the cavity of the cerebral vesicle, and a foot part which is contained within a mound of cells on the ventral wall of the cerebral vesicle. The junction between these two parts is probably the transducer region.

The transducer region is a complex system of folded cell membrane. Distortion of this system during rotation of the tadpole while swimming probably evokes changes in the neurones which surround the foot process of the otolith cell. One of these neurones is connected to the cerebral ganglion by a process which may be an axon. Fibrils extend from the transducer region of the otolith cell to the basement membrane, and probably serve to resist distortion of the transducer region.

The foot process of the otolith cell is connected to the surrounding cells by specializations of the cell membrane similar to attachment plaques.

The observations suggest that the otolith has been evolved from a cilium.
The use of the word ‘dense’ in microtechnique
Authors: Baker John R.
Published: April 2021

The word ‘dense’ has been used in 3 quite different senses in descriptions of dyed microscopical preparations, and considerable misunderstanding has resulted.
A note on the fine structure of a spirochaete
Authors: Grimstone A. V.
Published: April 2021

A description is given, based on high-resolution electron micrographs of thin sections, of the structure of a spirochaete from the gut of a cockroach, Cryptocercus punctulatus. There is a central cell-body, the structure of which resembles that of a bacterium. Two kinds of granule are abundant in the cell-body: large ones, 150 to 250 Å in diameter, of unknown composition, and small ones, identified as ribosomes, which may be arranged in whorls on the inner surface of the bounding membrane. Numerous small chromatin bodies are present. The bounding membrane of the cell-body is complex in structure. The cell-body is loosely enveloped by a sheath, made up of a thin membrane supporting a coarsely filamentous outer layer. In the space between sheath and cell-body is a loose bundle of 60 to 100 fibres. These are 140 Å in diameter and are coiled helically around the cell-body. They resemble bacterial flagella and are thought to be responsible for the movements of the organism.
The fine structure of the respiratory tree in Cucumaria
Authors: Doyle William L. , Frances Mcniell G.
Published: April 2021

The delicate tubules of the respiratory tree consist of 4 layers: a lining epithelium, a thick mucoid layer containing collagenous filaments, a smooth muscle net, and a coelomic epithelium. The free surfaces of both epithelia have well developed plasmodesms. Amoebocytes are present in all layers and the spherules of one type are considered to be precursors of the mucoid substance; another amoebocyte may be a fibroblast. Perpendicularly oriented smooth muscle fibres, as well as those parallel to each other, are linked by desmosomes ensuring synchronous contraction. Secretory activity is evident in distended cisternae of the endoplasmic reticulum of certain epithelial cells and in the vacuoles of the lining epithelium.
The fine structure of the cyst wall of the metacercaria of Fasciola hepática
Authors: Dixon K. E. , Mercer E. H.
Published: April 2021

Observations with the electron microscope have shown that 4 major layers can be distinguished in the cyst wall : an outer tanned-protein layer, consisting of a meshwork of irregular bodies made up of cigar-shaped particles ;a predominantly mucopolysaccharide, finely-fibrous layer, closely adherent to the tanned layer;an inner, mainly mucopolysaccharide layer, which can be resolved into two layers differing in fine texture ;a dense, compact layer, composed of numerous protein sheets stabilized by disulphide linkages. This layer is formed from tightly wound scrolls, developed in intracellular vacuoles, which are unrolled at the surface of the animal after secretion.
The behaviour of tissue slices in chromate solutions: a study of the comparative importance of the tonicity and osmotic concentration of fixative systems
Authors: Bernard George R. , Wynn Gail G.
Published: April 2021

A study was made of the weight changes undergone by slices of rat liver, kidney, and other organs immersed in certain fixatives containing chromium. In some experiments the data could be interpreted as indirect measurements of the fixative’s ‘effective’ osmotic pressure, or ‘tonicity’, a property which usually differs from the fluid’s ‘total’ osmotic pressure. In the case of kidney slices exposed to aqueous potassium dichromate, the rapidly occurring and reproducible responses seem proportional to the fixative concentration; no clear-cut differences were observed with liver slices similarly exposed. Altering the concentration of chromic acid did not affect quantitatively or qualitatively the response patterns of either tissue. Responses of slices to combinations of dichromate and formalin suggest cumulative action of the two moieties. The response patterns to the latter fluids could be modified by the addition of ‘indifferent’ substances such as sucrose.
The cytochemical localization of alkaline phosphatase in the testicular nephridia of the Indian leech, Hirudinaria granulosa, with special reference to the inner lobe
Authors: Dev Bhoomittra
Published: April 2021

Previous studies by the author have revealed the intense localization of alkaline phosphatase in the initial-lobe cells and in the intracellular central canal on its first ‘round’ in the testicular nephridia of Hirudinaria granulosa. The present work throws light, for the first time, on the detailed cytochemical localization of the enzyme in the region where these two components communicate with each other. Openings of the central canal into an inner-lobe cell and of the latter into an initial-lobe cell have been noticed at one and the same level. An enzymatically negative inner-lobe cell serves as a bridge between the two positive zones. The bridge is, however, rarely observed because of the tendency to direct coalescence between the two enzymatically positive parts. The initial lobe sometimes opens into the central canal by means of more than one aperture. After the opening of the initial lobe into the central canal, the latter loses its enzymatic activity, and the radially arranged tubular inner-lobe cells disappear. The enzymatic activity in the peripheral cytoplasm of the intracellular central canal is usually more intense towards the point of its union with the initial lobe. The functional significance of the findings is discussed. Evidence for the concentration of the enzyme round the nucleus and in the nucleolus has also been noticed in the nephridial cells.
Spittle-production and tube-building by cercopoid nymphs (Homoptera). 3. The cytology and function of the fibril zone of the Malpighian tubules of tube-building nymphs
Authors: Marshall A. T.
Published: April 2021

In tube-building nymphs, the proximal segments of the nymphal Malpighian tubules consist of two secretory zones, an anterior fibril zone and a posterior granule zone. This fibril zone clearly corresponds in position to (and is possibly homologous with) the anterior part of the proximal segment of the Malpighian tubules of spittlebug nymphs.

The cells of the fibril zone contain numerous stacked mucofibrils which are periodically extruded into the tubule lumen. Slight cytoplasmic vacuolation occurs immediately before and during extrusion. The extruded mucofibrils are passed down the hindgut and out to the exterior through the anus. The mucofibrils form an essential component of the nymphal dwelling tube and are laid down by characteristic movements of the abdominal tip.

The tube-building cercopoids (Homoptera, super-family Cercopoidea, family Machaerotidae) are divisible into two subfamilies, Enderleiniinae and Machaerotinae, of which the former is probably the more primitive (Maa, 1963)·

Nymphs of the tube-building cercopoids construct conical dwelling tubes on the stems of their host plants (Ratte, 1884; Maki, 1914; Hacker, 1922; Evans, 1940; Maa, 1963). The mode of formation of the dwelling tubes does not appear to have been previously reported and forms the subject of the present investigation.
Morphogenesis of the residual body of the mouse testis
Authors: Firlit Casimir F. , Davis Joseph R.
Published: April 2021

A histochemical study of the detached cytoplasm of the maturing spermatid has been carried out. The detached cytoplasm has been designated as the cytoplasmic body and 4 distinct phases in its morphogenesis have been reported. The cytoplasmic tag of stage 11 of spermiogenesis has been designated as phase CB-1 in the morphogenesis of the cytoplasmic body. It was found to contain numerous granules of RNA, polysaccharides, and lipid. During phase CB-2 and CB-3, coalescence and fusion of these granules occurs, which result in a centrally-oriented plaque of RNA and glycogen, peripheral satellites containing polysaccharides, and large globules of lipid. During phase CB-4, the cytoplasmic body membrane becomes approximated to the plaque and at this stage of development the cytoplasmic body can be compared to the ‘residual bodies’ of Regaud. Peripheral migration towards the basement membrane of the seminiferous tubule now occurs. Some of the residual bodies undergo phagocytosis by Sertoli cells, while others eventually occupy a position at the level of the spermatogonia.
The Rhabdom of the Lobster Eye
Authors: RUTHERFORD D. J. , HORRIDGE G. A.
Published: April 2021

The spindle-shaped rhabdom of the lobster is a compact mass, 125µlong, by 25 µ by 25µ, at the widest point, composed of microvilli which extend from the 7 surrounding retinula cells. The characteristic feature is that the microvillar tubules are arranged in flat saddle-shaped plates, each about 2 µ. thick, which lie superimposed successively upon each other in a vertical stack along the optical axis, with the tubules of each plate at right angles to the tubules of the adjacent plates. The tubules are 60 to 100 mµ in diameter, and arise in groups of about 9 tubules from common stems where the edge of the plate meets the body of the retinula cell. The rhabdom appears to be partially separated from the cells by membranes and cisternae of the endoplasmic reticulum of the retinula cells. The commonest components of the retinula cells are rhabdomere vesicular spheroids, Golgi membranes, lysosomes, pigment granules, and endoplasmic reticulum. Thespheroids, Golgi membranes and lysosomes appear to be related. Large amorphous globules, which appear to be more abundant in darkadapted eyes, lie in rows in the axons of retinula cells and appear to be travelling along them.
The organization and replacement of the epidermis in acoelous turbellarians
Authors: Dorey A. E.
Published: April 2021

Five species of acoelous turbellarians have been studied: Convoluta roscoffensis Graff, C. convoluta (Abildgaard), Aphanostoma diversicolor Oersted, Otocelis rubropunctata (Schmidt), and Avagina incola Leiper. A culture-method for C. roscoffensis is described. Experiments have been carried out with various preparative methods for electron microscopy, and a method that yields adequate results with acoel material is described.

The epidermis is not syncytial, as has been maintained by some authors, but is composed of distinct, uninucleate cells. The cytoplasm of these has never been found to be continuous between cells, nor between the epidermis and the tissues that lie below it. The basal surfaces of the cells are intimately associated with the muscle layers and with other peripheral tissues. A brief account of the cytology of the epidermal cell is given.

The fine structure of the cilia and their rootlets is described from observations on sectioned material and on isolated, ‘negatively stained’ specimens. The rootlets of adjacent cilia make contact with each other in such a way as to preserve a hexagonal arrangement of the cilia, and yet to allow some degree of dimensional flexibility. The organization of the ciliary array over the surface of the animal is described. The ciliary ‘streamlines’ radiate outwards in all directions from a region (occupied by the frontal gland) at the anterior tip of the animal, and converge on a point at the posterior tip. This pattern is interrupted only in small regions near the mouth and the genital openings. The directions of beat and of metachronal-wave propagation are uniformly related to each other, and to the structural pattern, at all points.

Epidermal replacement has been studied experimentally in C. roscoffensis. Batches of animals were subjected to a surface-abrasive treatment, and epidermal-replacement cells were later identified in the parenchyma. The structure and situation of these is described, though their origin is not known.

The findings are discussed in relation to the variety and possible functions of ciliary rootlets, and to current concepts of acoel organization.
The cytology and histochemistry of the digestive gland cells of Helix
Authors: Sumner A. T.
Published: April 2021

The digestive gland tubule epithelium of Helix aspersa is made up of 4 cell-types : thin cells, digestive cells, calcium cells, and excretory cells. Thin cells are narrow and undifferentiated. They divide by mitosis and are believed to develop into other celltypes. Digestive cells are highly vacuolated phagocytic and absorptive cells. Food materials are taken in by phagocytosis and are concentrated and digested in the vacuoles in the cell. When digestion is complete, the residual indigestible material in the vacuoles, and excretory material in the form of small granules of lipofuscin, are cast out of the cell surrounded by a portion of cytoplasm. Calcium cells are secretory, with a prominent Golgi apparatus and a high concentration of RNA in the cytoplasm. Most of the cell is occupied by spherules which contain calcium; apically there are protein granules which contain a high concentration of tryptophane. Both these types of inclusion are extruded from the cell. Protein granules may be zymogen granules, but the function of the calcium spherules is not known. Excretory cells are degenerate, and probably derived from calcium cells. They consist chiefly of a large vacuole, surrounded by a little cytoplasm. The vacuole contains one or more granules of lipofuscin. Similar granules can be found in the faeces, and thus they are excretory material.
Colour photomicrography of crystals in Brownian movement
Authors: Sassoon H. F. , Parsons M. H. C.
Published: April 2021

Colour photomicrography of particles in Brownian movement has been achieved on High-Speed Ektachrome film using a flash source giving about 200 joules in 250 μsec. The design and operation of a prototype apparatus is described, and its potentiality for further development discussed.
Observations on the mastigonemes of two Chrysophyceae using negative staining
Authors: Bradley D. E.
Published: April 2021

This paper describes a negative staining procedure for small appendages on relatively large organisms, and its application to the study of the ultrastructure of the mastigonemes of two chrysomonads. They have a remarkably complex structure, appearing as tubes with a layer of ragged material on their surfaces. In spite of the large amount of detail visible, it is not possible to propose a definite model of their structure.
The fine structure of the olfactory surface of teleostean fishes
Authors: Bannister L. H.
Published: April 2021

The olfactory receptors of Phoxinus are of at least two distinct types: those with ciliated tips, and those with rod-shaped tips to their dendrites. Both Phoxinus and Gasterosteus possess ciliated receptors with 4 to 6 cilia arranged in a ring on each dendritic tip. The cilia resemble non-sensory motile cilia in most respects. They are, however, shorter, and lack ‘arms’ on the outer ring of double fibrils. They also lack striated rootlets, but possess basal feet, which point towards the centre of the ring of cilia. The rod-tipped receptors contain three or more longitudinally oriented bundles of fibres. Microtubules are present in receptor dendrites, in supporting cells, and in ciliated non-sensory cells. Their mean diameter in dendrites is 180 Å.

The different forms of receptor, and their function, are discussed.
The Origin of Proteid Yolk in Drosophila melanogaster
Authors: Hsu W. Siang
Published: April 2021

1. The origin of the proteid yolk granules in the eggs of Drosophila melanogaster has been traced to precursors embedded in the matrix material of flakes which are emitted by the nucleoli of the nurse cells.

2. These emissions are of a lipoidal nature, as shown by their behaviour towards fixatives and stains. They have never been observed to come from the nucleolus of the germinal vesicle.

3. The precursors, once released from the matrix of the flakes, develop directly into individual proteid yolk granules.
The Behaviour of the Nucleus during Spermatogenesis in Fasciola hepatica
Authors: John Bernard
Published: April 2021

1. The behaviour of the nuclei of the male germ cells of F. hepatica L., as observed after fixation in Carnoy 6:3:1, is described and illustrated. All phases of the division and maturation of the male germ cells occur within the multi-branched and tubular testes. The daughter cells by remaining in association and dividing synchronously throughout these divisions eventually give rise to a spermatid rosette of thirty-two component cells. During spermiogenesis the nucleus of each individual spermatid cell undergoes a progressive elongation and is converted into an undifferentiated and homogeneous filiform thread.

2. The occurrence of globules of unknown origin, composition, and function is recorded within the peripheral border of spermatogonial primordia. Pycnotic primordial spermatogonia are also observed to originate in the peripheral testis cells.

3. The cyto-morphology of the chromosome complement is recorded in relation to size and the position of the attachment-constriction. The somatic number in the male cells is found to be 12 (diploid).

4. From a study of metaphase configurations chiasmata are shown to exhibit a normal distribution and there is no apparent localization of the chiasmata. The infrequent occurrence of chromatid bridges at anaphase I is correlated with the retention of an unusually large number of interstitial chiasmata.
Miscellaneous Contributions to Microtechnique
Authors: Baker John R. , Jordan Barbara M.
Published: April 2021

1. The glycerine in Mayer’s glycerine and albumen serves no useful purpose.

2. If about one-half of the haematoxylin in such solutions as those of Heidenhain and Ehrlich be oxidized by sodium iodate, the dyes are ready for use the moment they have been made up and also keep well.

3. In using crystal violet for staining chromosomes, it is best to fix the dye by an aqueous (instead of the usual alcoholic) solution of iodine.
Standardization of Methyl Green for Specific Staining of Egg-shell Material in a Trematode
Authors: Smyth J. D.
Published: April 2021

1. The specificity of a number of samples of methyl green for egg-shell material in Fasciola hepatica was investigated.

2. A method for distinguishing between specific and non-specific stains by paper chromatography is described.

3. Specific stains gave almost identical chromatograms with an Rf value of 0 83 for both green and violet constituents. Non-specific samples gave chromatograms with an Rf of 0·65 for the green constituent and an Rf of 0·84 for the violet constituent. The liquid phase used was a mixture of organic solvents in the following proportions: ethanol, 100; water, 80; n-butanol, 100; cellosolve, 100.

4. The application of this technique has led to the production of a methyl green, named Methyl Green M.2, specific for shell material in Fasciola.
The Relationship of the ‘A’ and ‘B’ Cells of the Pancreatic Islet Tissue of the Grass-snake (Natrix natrix)
Authors: Barrington E. J. W.
Published: April 2021

An account is presented of some cytological characteristics of the pancreatic islet tissue of the grass-snake (Natrix natrix helvética), based upon supra-vital observations and upon the application of different techniques of fixation and staining. It is concluded that the so-called ‘A’ and ‘B’ cells contain granules of essentially the same type, and that they are stages in a single secretory cycle. It is suggested that the ‘A* cells constitute a relatively inactive storage phase, while the ‘B’ cells are concerned with the formation and discharge of the final secretory product, free phospholipine becoming demonstrable in association with the granules during this latter phase.
Cytological Studies of the Neurones of Locusta migratoria Part I. Cytoplasmic Inclusions of the Motor Neurones of the Adult
Authors: Shafiq Saiyid Ahmad
Published: April 2021

The motor neurones of Locusta migratoria have the following inclusions in their cytoplasm:

(a) granular and filamentous mitochondria;

(b) lipochondria of various sizes. These are osmiophil and sudanophil. They also segregate neutral-red and other vital dyes. These ‘neutral-red bodies’ are shown not to be new formations in the cells, as was believed by Beams and King. The lipochondria may perhaps be homogeneous bodies, though in fixed preparations and also in life they sometimes appear to have a cortex and medulla. The osmiophil platelets and the straight and curved rods are shown to be artifact appearances caused by the action of Golgi techniques on the lipochondria, &c.;

(c) irregular vacuoles of various sizes;

(d) yellow globules in some neurones, especially from old locusts.
Measurements on Sea-urchin Eggs with an Interference Microscope
Authors: Mitchison J. M. , Swann M. M.
Published: April 2021

Observations and measurements with an interference microscope on sea-urchin eggs have established the following points.

(1) The refractive index (R.I.) of the cytoplasm of the unfertilized egg is 1·375, which is equivalent to a concentration of solid matter of about 25 per cent. Very similar values were obtained from eggs 10 minutes after fertilization.

(2) There may be a small drop in the R.I. during the interphase before the first cleavage and during mitosis, but this is not greater than about 0·2 per cent., which is equivalent to a change in concentration of 2 per cent.

(3) The nucleus of the unfertilized egg has an R.I. of 1·360, equivalent to a concentration of 16 per cent.

(4) The R.I. of the mitotic figures is lower than that of the cytoplasm, by a ratio of 0·89 in metaphase. This is probably due to the absence of granules in the mitotic figures, since a similar ratio is obtained between the clear and the granular regions in centrifuged eggs.

(5) In metaphase, the chromosomes have the same R.I. as the spindle and are invisible. During the later stages of mitosis their R.I. drops, and they become visible.

(6) The dry thickness of the fertilization membrane is about 160 A. There is evidence of a colloid in the perivitelline space at a concentration of about 0-07 per cent.

(7) The jelly has a concentration of less than 0·0055 per cent.