bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies in the Retina
Authors: Bernard H. M.
Published: April 2021

This sixth paper concludes the series. 1 It was my original plan to publish any observations I might be fortunate enough to make which threw light on the general structure of the retina, as introductory to a series of comparative studies on the eyes of different groups of animals, the ultimate object being to accumulate and elaborate the evidence which had seemed to me to point to a mechanical theory of vision. 2 Whether the original plan will ever be carried out remains to be seen. I express the doubt because the new matter contained in this paper threatens to draw me off into other and larger fields than the retina. The discovery of continuous nerve-paths through the retina along lines in which no one acquainted with the current views and theories would have thought of looking for them, seems to demand some revision and readjustment of modern doctrines with regard to several important morphological problems. And yet there is not so much that is really new in this paper, for, when critically reviewed, it will be found that nearly every fact has been seen and described by other workers. What the retina has now revealed is not so much new facts as new clues, which will, I believe, enable us to co-ordinate a number of hitherto isolated and, on that account, often neglected observations.
The Descriptive Anatomy of the Brain and Cranial Nerves of Bdellostoma Dombeyi
Authors: Worthington Julia
Published: April 2021

The species principally used for this investigation was Bdellostoma Dombeyi, the ordinary hag-fish of the Pacific coast; some points of the gross anatomy, however, were worked out from specimens of B. Forsteri, from the Cape of Good Hope. There is no difference in the gross anatomy of the two species but that of size, and the B. Forsteri, being slightly larger, made some of the fine dissection easier.
The Fixation of the Cypris Larva of Sacculina carcini (Thompson) upon its Host, Carcinus mænas
Authors: Smith Geoffrey
Published: April 2021

The fixation of the Cypris larva of Sacculina has hitherto been successfully observed only by Delage (1), and since a considerable degree of doubt has been thrown on his account it may be of interest to record that I have been able this autumn, at Plymouth, to rear the larvæ and observe all the stages of fixation upon their host. My inability to obtain the Cypris larvæ of any of the Rhizocephala at Naples had left a gap in my observations, which I am now in a position to fill, and thus I am able to present a complete account of the life-history of Sacculina from my own observations (2).
Development and Origin of the Respiratory-Organs in Araneæ
Authors: Purcell W.F.
Published: April 2021

It is just one hundred years ago that the first anatomical account of the lung-books of Arachnida was published by Meckel (‘09), who, like his immediate successors, looked upon these organs as gills, and it was not until 1828 that their pulmonary nature was recognised by Johannes Miiller (‘28a, ‘28b) and Straus-Durckheim (‘28). The latter was also, I believe, the first to point out (p. 315) that the lung-books could be regarded as a special form of tracheae, a view which was later on elaborated by Leuckart (‘48, p. 119 note, and ‘49) and for a time generally accepted, until the appearance of Ray Lankester’s paper,”Liraulus: an Arachnid,”in 1881, opened up the probability of the branchial origin of these organs.
The Phylogeny of the Tracheæ in Araneæ
Authors: Purcell W. F.
Published: April 2021

In an excellent paper on the tracheæ of spiders E. Lamy (:02) has given an account of the tracheæ of thirty families of Araneæ, so that only four small and comparatively rare families, comprising 1—3 genera each, remain, of which the tracheæ are still unknown. It is now possible, therefore, to consider the tracheal systems of the Araneæ as a whole from a phylogenetic point of view, and as I barely touched upon this point in my paper (:09) on the development and origin of the respiratory organs in spiders, I propose to make it the subject of the present paper.
Some Points in the Physiology of Lamellibranch Blood-Corpuscles
Authors: Drew G. H.
Published: April 2021

The investigations described in this paper were carried out on the blood of Cardium norvegicum. This animal was chosen as a type as it presents several features which render it especially suitable for hæmatological work. Among these may be mentioned the ease with which the blood can be obtained in large quantities, the relatively large size of the corpuscles, the great vitality of the animal, and its large and readily protruded foot.
On the Development and Structure of the Trochophore of Hydroides uncinatus (Eupomatus)
Authors: Shearer Cresswell
Published: April 2021

While working at Naples some years ago, I was led to investigate the early development of the Annelid Eupomatus with a view to determining the origin of the mesoblast bands and their relation to the head-kidneys. This species is common at Naples and breeds throughout the year. The blastulae and gastrulæ are very hardy, and development is normal under the adverse conditions of beat and impure seawater incidental to their study under laboratory conditions. Fertilisation takes place quickly when the ripe generative products are brought together, and material can be easily obtained of any stage. The trochophores can be readily reared to the adult worm in small jars of sea-water to which sufficient food is added from time to time, in the form of cultures of the common Diatom Nitzschia closterium. On this they rapidly grow, and soon attach themselves to the sides of the culture jars and form their tubes.
Studies on Parasitic Protozoa: I. The Flagellate Polymastix and its Affinities with the Trichonymphida
Authors: Mackinnon Doris L.
Published: April 2021

The Protozoa known as Trichonymphids, parasites of the gut of certain orthopterous insects, have for long presented difficulties to the systematist.
Obituary
Authors: Kate Greville Robert
Published: April 2021

We depart from our ordinary rule of not noticing the death of distinguished men, as those who contribute to our pages usually find a place in the annual address of the President of the Microscopical Society. In Dr. R. K. Greville, however, the world has not only lost a distinguished botanist, and a good and a great man, but we have lost a contributor whose place we cannot hope to supply, and whose contributions have been more numerous and more constant, and, we believe we may add without offending any one, more valuable, than any other papers in our pages. These papers have been entirely devoted to the Diatomaceæ, and present a series of minute and careful observations in these minute organisms such as has scarcely been presented during the same time in any other department of natural history. The illustrations of Dr. Greville’s observations were all made under his own superintendence, from the beautiful and accurate drawings of his own pencil.
On the Spermatogenesis of the Louse (Pediculus corporis and P. capitis), with some Observations on the Maturation of the Egg
Authors: Doncastcr L. , Cannon H. G.
Published: April 2021

The main facts of the spermatogenesis have been given in Section 3 A above. The most important points are as follows: The somatic chromosome number of both sexes is twelve, but spermatogonial mitotic figures show only six. There is some evidence that these are double, and we ascribe the existence of the apparently haploid number in the spermatogonia to premature pairing.There is only one spermatocyte division, which is extremely unequal, leading to the separation of a minute polar-body-like cell which degenerates.The centrosome of the spermatid is double, and from each half an axial filament grows out, so that the developing spermatozoa have two conspicuous axial filaments.The development of the mitochondrial body is described.The acrosome is derived from a deeply staining body which appears in the spermatocyte and becomes applied to the nucleus of the spermatid like a cap.The existence of a deeply stained rod, of unknown origin and fate, in the growing oocyte, and of a posterior mass of stained granules in the mature egg, is shortly referred to. The egg nucleus undergoes two polar1 divisions, and fertilisation appears to be essential if the egg is to develop.Breeding experiments did not confirm Handle’s observation that broods consisting only of males or only of females are frequent. Some broods with great preponderance of one or the other sex were obtained.
The Development of the Pronephros in the Common Perch (Perca fluviatilis L.)
Authors: Stroer W. F. H.
Published: April 2021

This investigation into a series of Perea fluviatilis started some time ago.
The Physiology of the Cuticle and of Ecdysis in Rhodnius prolixus (Triatomidae, Hemiptera); with special reference to the function of the oenocytes and of the dermal glands
Authors: Wigglesworth V. B.
Published: April 2021

Ecdysis in insects is the homologue of metamorphosis, and there can be small prospect of understanding the complex process of metamorphosis until the physiology of ecdysis has been adequately described. It is somewhat surprising, therefore, that so little attention should have been paid to the histological changes which take place during the moulting of non-metabolic insects ; and the present work is an attempt to describe certain of these changes in the blood-sucking bug, Rhodnius prolixus.
On the Nature and Functions of the Amoebocytes of Ostrea edulis
Authors: Takatsuki Shun-ichi
Published: April 2021

There are two kinds of corpuscles in the blood of the oyster; one consists of granular, the other of hyaline amoebocytes. The granular amoebocytes are amoeboid, though the speed of their movement is slow. The granules are yellow or yellowish green in the fresh condition. The granules are neutrophil with a tendency to become stained by the basic dyes intra vitam. Granules can never be distinguished in fixed and stained amoebocytes. The amoebocytes are distributed everywhere throughout the body, an especially large number being normally present around the gut. The so-called ‘pseudopodia’ of the amoebocytes are described and their nature discussed. The effects of several kinds of reagents on amoeboid movement and on the amoebocytes are described. The amoebocytes become entangled with one another by bristle-like ‘pseudopodia’, or by elongated strands of hyaline ectoplasm outside the body. There is no true coagulation of the blood, and no fibrin production. The mechanism of phagocytosis is described and discussed. Sucroclastic, lipoclastic, and proteoclastic enzymes are present in the amoebocytes and enable the amoebocytes to digest intracelluarly. The optimum action of the amylase is about pH 7·0 and of the proteoclastic enzymes about pH 8·0. These optima are not very well marked. A complete oxidase system is present, revealed by the indophenol reaction, by the power of reducing indigo carmine, a process which is irreversible, and by a slight reaction with guaiacum. The amoebocytes can absorb glucose both in the gut and the mantle cavity. There is no evidence of absorption of soluble matter nor of solid substances by the epithelium of the mantle cavity, e.g. gills, labial palps, &c., other than by the agency of amoebocytes. The amoebocytes play a prominent part in excretion. They reject directly foreign or indigestible matter by way of the epithelium of the excretory organ, pericardium, surface of the auricle, rectum, and mantle cavity.
The Cytology of the Mid-gut and Hepatic Caeca of Periplaneta orientalis
Authors: Gresson R. A. R.
Published: April 2021

The observations here recorded on the general structure and arrangement of the epithelial cells of the mid-gut and hepatic caeca agree fairly closely with previous accounts for the cockroach; The hepatic Caeca and anterior region of the mid-gut are chiefly secretory, while the posterior part of the mid-gut is mainly absorptive in function. In the caeca and anterior part of the mid-gut periods of secretion alternate with periods of absorption. The secretory cells degenerate after a time, and are replaced by young cells which are at first, in all probability, absorptive in function. The mitochondria of the secretory cells are in the form of filaments in the basal region and in the neighbourhood of the nucleus; those between the nucleus and the lumen are usually granular. In certain cells most or all of the mitochondria are granular. The mitochondria of the absorptive cells are closely similar to those of the secretory cells. Mitochondria were identified in the replacement cells. The Golgi elements of the secretory cells are in the form of rods and granules; some of the curved rods enclose a lightly impregnated material; the elements are situated chiefly in the neighbourhood of the nucleus. The Golgi bodies of the absorptive cells are often smaller, and extend farther towards the lumen than do those of the secretory cells. Golgi elements were identified in the older replacement cells. It is suggested that material is separated out under the influence of the mitochondria, chiefly in the basal region of the cell, and that this material moves to the vicinity of the nucleus, where, under the influence of the Golgi elements, it is used in the formation of the secretory granules. Recent work having a bearing on the present investigation is discussed.
The Origin and fate of the Membranes surrounding the Grasshopper Egg; together with some Experiments on the Source of the Hatching Enzyme
Authors: Slifer Eleanor H.
Published: April 2021

Campbell (1929) and Jahn (1935 a, 1935 5, 1936) have recently investigated the chemical and physical properties of several of the egg coverings of Melanoplus differentia li s. A detailed account of the formation, structure, and fate of the membranes surrounding the acridian egg is, however, still lacking. Observations already in the literature are incomplete and frequently contradictory (Meissner, 1855; Leuckart, 1855; Riley, Packard, and Thomas, 1877; Korschelt, 1887; Uvarov, 1928; McNabb, 1928; Nelsen, 1931, 1934a, 19345; Husain and Roonwal, 1933; Slifer and King, 1934; Roonwal, 1936). In the first part of the present paper an attempt has been made to follow the history of the egg coverings from the time of their formation to the time when the young insect hatches.
On the Nature of the Discoloration of the Arctic Seas
Authors: Brown Robert
Published: April 2021

The peculiar discoloration of some portions of the frozen ocean, differing in a remarkable degree from the ordinary blue or light green usual in other portions of the same sea, and quite independent of any optical delusion occasioned by light or shade, clouds, depth or shallowness, or the nature of the bottom, has, from a remote period, excited the curiosity or remark of the early navigators and whalemen, and to this day is equally a subject of interest to the visitor of these little-frequented parts of the world. The eminent seaman, divine, and savant, William Scoresby, was the first who pointedly drew attention to the subject, but long before his day the quaint old searchers after a North-west Passage “to Cathay and Zipango “seem to have observed the same phenomenon, and have recorded their observations, brief enough it must be acknowledged, in the pages of ‘Purchas—His Pilgrimes.’ Thus, Henry Hudson, in 1607, notices the change in the colour of the sea, but has fallen into error when he attributes it to the presence or absence of ice, whether the sea was blue or green—mere accidental coincidences. John Davis, when, at even an earlier date, he made that famous voyage of his with the “Sunshine “and the “Moonshine,” notes that, in the strait which now bears his name, “the water was black and stinking, like unto a standing pool.” More modern voyagers have equally noted the phenomenon, but without giving any-explanation, and it is the object of this paper to endeavour to fill up that blank in the physical geography of the sea. In the year 1860 I made a voyage to the seas in the vicinity of Spitzbergen and the dreary island of Jan Mayen, and subsequently a much more extended one through Davis’ Straits to the head of Baffin’s Bay, and along the shores of the Arctic regions lying on the western side of the former gulf, during which I had abundant opportunities of observing the nature of this discoloration. At that period I arrived at the conclusions which I am now about to state. In the course of the past summer I again made an expedition to Greenland, passing several weeks on the outward and homeward passages in portions of the seas mentioned, during which time I had an opportunity of confirming the observations I had made seven years previously, so that I consider that I am justified in bringing my researches, so far as they have, gone, before the Botanical Society.
On the Structure of the Lachrymal Glands
Authors: Boll Franz
Published: April 2021

Recently, in histological researches, peculiar star-shaped cells have been noticed in the aciniferous glands. Krause was the first man who isolated these, in the case of the parotid of a cat, by means of maceration in vinegar. He is inclined to treat them as nervous organs. Henle also describes stellate cells in the walls of the rennet glands, as well as the parotid and mammæ. He also thinks that they are most likely of a nervous character, although he has. never seen any connection with the nerve-fibres. Pflueger describes multipolar cells in the salivary glands of the rabbit. He holds them to be multipolar ganglion-cells, and observed on one side their connection with the fibres, and on the other-side with the secretory epithelial cells. Finally, Kölliker has made closer researches concerning the cells in question in the salivary glands. He considers them to be simply forms of the covering structure of the alveolus, which seem to him to represent a kind of reticulum.
Observation, on the Breeding and Development of the viviparous fish, Heterandria formosa
Authors: Fraser Elizabeth A. , Renton Rachel M.
Published: April 2021

A short account is given of the breeding habits of Heterandria formosa in an aquarium. The ovary and the mature ovum are briefly described, the noteworthy feature of the ripe ovum being the small quantity of yolk. 8. Degeneration of ova is found to be a common occurrence in unfertilized females, and to a less extent in those full of developing embryos. The method for ensuring the fertilization of the egg within the follicle is portrayed. Over the area where the spermatozoa have entered the cells of the ovarian epithelium and those of the follicle form a solid plug which eventually disrupts to enable the fully developed embryo to escape into the cavity of the ovary. It is characteristic of early development that the egg is encircled by a unilaminar ectoderm before there is any visible differentiation into endoderm and mesoderm. Owing to the scarcity of yolk only a few periblast cells arise and no syncytial layer is formed. The primitive-germ cells are visible at an early stage within the apparently undifferentiated mesendoderm cells. A striking feature is the large size of the pericardium and its growth upwards as a pericardium hood which completely surrounds the head region of the embryo. Over the walls runs a network of blood-vessels from which the maternal capillaries become eventually separated by only an attenuated layer of protoplasm. Both respiration and nutrition are effected through the follicle. A remarkable specialization is the development of a urinary bladder which expands into a thin-walled vesicle of enormous dimensions, finally occupying almost the entire area formerly filled by the pericardium and the yolk-granules. The development of Heterandria is compared with that of other viviparous fishes. The significance of the unusual features in early and late development is discussed and some comparisons are made with the conditions in higher vertebrates.
Facts bearing on the Structure and Arrangement of a Nervous Mechanism demonstrated in the Auricle of the Frog’s Heart
Authors: Beale Lionel S.
Published: April 2021

The rhythmic contractions of a portion of the muscular tissue of the heart continue for some time after it has been severed from the rest of the organ and removed from the body. A closely allied fact is observed in the case of the muscular coat of the intestinal canal; and in some muscles of insect larvæ, which have been removed from the body with due care, the muscular tissue continues to contract for some time after its removal. The muscles of the common maggot will retain their contractility for an hour or more after they have been placed upon a glass slide (“Croonian Lecture,”‘Proceedings of Royal Society,’ May 11, 1865, p. 229).
Monograph of Monera
Authors: Häckel Ernst
Published: April 2021

While on the one hand the kingdom of the Protista is increased by the Labyrinthulea with a separate class, on the other hand it may now be satisfactorily proved that another group of Protista should be removed from this kingdom, and referred to the animal kingdom as decided animals. These are the Sponges, of whose animal nature very decided morphological indications have been very reeently discovered. As long ago as 1854, Leuckart, the illustrious founder of the sub-kingdom Coelenterata, in his yearly report upon the progress of zoology (in the ‘Archiv für Naturgeschichte’), united the sponges or Poriphera with the Coelenterata, by a comparison of the canal system of the sponges with the cœlenteric gastrovascular apparatus of the true Coelenterata.
A Phase Contrast Study of the Blood-cells in Prodenia Larvae (Order Lepidoptera)
Authors: Colvard Jones Jack
Published: April 2021

The various classes of blood-cells in air-dried, Wright-stained blood-smears described by Yeager (1945) from heat-fixed Prodenia can be recognized in unfixed and unstained preparations with the phase microscope. With only one exception, the blood- cells do not undergo extensive transformations in vitro for at least one hour. Hence, the blood-cells may be accurately identified and differentially counted by phase microscopy. Two kinds of blood-cells undergo marked alterations in appearance on heatfixation, whereas the other types remain mostly unmodified. One type of blood-cell, the oenocytoid, typically undergoes a marked change in character in vitro in unfixed blood. Several changes in Yeager’s classification of insect blood-cells are proposed, and it is suggested that this new system will be found sufficient for identifying and comparing blood-cells in the different orders of insects.
The Innervation of the Gut of the Brown Trout (Salmo trutta)
Authors: Burnstock G.
Published: April 2021

The extrinsic and intrinsic innervation of the trout gut has been examined by using methylene blue, osmium tetroxide, and silver staining techniques. Left and right vagus nerves penetrate the oesophageal wall and run between the longitudinal and circular muscle-coats of the stomach, but do not reach the intestine. Branches of these nerves anastomose with each other and become incorporated into Auerbach’s plexus. Pericellular endings of vagal fibres are found about enteric neurones in the stomach, while some fibres end directly on the striated muscle-cells of the oesophagus. A single, fine, anterior splanchnic nerve anastomoses along the major branches of the coeliaco-mesenteric artery to supply both the stomach and intestine. Most of the splanchnic fibres pass directly into the smooth muscle-coats, but some fibres run into the subserous plexus. Two posterior autonomic nerves provide separate innervation of the rectum. Three main types of nerve-cells have been distinguished in the gut by their distribution as well as structure. (a) Small uni-, bi-, and multi-polar cells (10-15 μ in diameter) form the main body of Auerbach’s plexus, lying between the muscle-coats. Throughout most of the gut they are not arranged in true ganglia, since only from 1 to 3 neurones occur at the nodes and many cells lie singly along the internodal connectives. (v) A smaller number of large multipolar neurones (30-60μ in diameter) lie halfembedded in the longitudinal muscle along the whole length of the gut, their principal axons passing down to lie between the muscle-coats in Auerbach’s plexus. (c) A third cell type consisting mainly of large mono-or bi-polar cells (30-70 µ in diameter) contributes to Auerbach’s plexus in the stomach only and is associated with the endings of vagus nerve-fibres. Bundles of nerve-fibres pass down through the circular muscle-coat from Auerbach’s plexus to join a loosely arranged plexus of nerve-fibres, the submucous plexus; but unlike Meissner’s plexus of mammals, which occupies a similar region, no nerve-cells are present. Nerve-endings, some of which may be sensory, are located at the bases of the mucous epithelial cells and are continuous with fibres forming a prominent subepithelial plexus from which fibres pass to both submucous and Auerbach’s plexuses. A subserous plexus and ‘interstitial cell network’ are also present in the fish gut. A quantitative study of nerve-cell densities in different regions of the trout gut revealed density peaks of 93 cells per square mm and 170 cells per square mm in the posterior cardiac stomach and anterior duodenum respectively. The ratio of small to large neurone types in Auerbach’s plexus is about 20 to 1 in all regions. The total number of nerve-cells in the whole gut was calculated to be about half a million.
The Feulgen Reaction in the Different Stages of the Life-cycles of Certain Sporozoa
Authors: Dasgupta B.
Published: April 2021

The nuclei of the male and female gametocytes of the malarial parasites (Plasmodium and Hepatocystis) are Feulgen-negative, while the nuclei of the gametocytes of Hepatozoon, which are not sexually differentiated, are Feulgen-positive. The nuclei of the male gametocytes of Eimeria are strongly Feulgen-positive, while the nuclei of the female gametocytes are Feulgen-negative. The nuclei of the male gametes of Plasmodium are Feulgen-negative, while the nuclei of the male gametes of Eimeria are strongly Feulgen-positive. DNA appeared to be present in the gametocytes of Plasmodium when the fluorescence method of Armstrong (1956) was employed.

Feulgen-positive inclusions have been found to occur in the cytoplasm of some of the oocysts of Plasmodium. The oocysts containing such inclusions may degenerate totally or partially. There is no evidence to relate this type of degeneration with the formation of Ross’s black spores. These inclusions have been found in abundance in the oöcysts of P. cynomolgi, while in those of P. gallinaceum they were found only once.

Certain Feulgen-positive granules have been found in the cytoplasm of some of the oocysts and the female gametocytes of Eimeria. These granules did not appear to be related to any degenerating changes. A probable loss of some of the nuclei during sporogony of Eimeria is discussed.

The nuclei in the early pre-erythrocytic schizonts of Plasmodium cynomolgi are Feulgen-positive, notwithstanding an earlier report to the contrary.
The Masked Lipids of Nuclei
Authors: Chayen J. , Gahan P. B. , La Cour L. F.
Published: April 2021

The histochemistry of masked lipids of chromosomes has been investigated with the aid of paper chromatographic procedures. At least three tightly bound associations of phospholipid with protein have been identified in calf thymus nucleohistone. Hence it seems likely that the ‘spurious’ reactions of nuclei and of nucleohistone, especially after extraction with lipid solvents, is a true indication of the increased availability of these closely linked phospholipids. Moreover, not more than about 10% of the material extracted by hot pyridine from calf thymus was fatty, the rest being watersoluble. After treatment of plant cells with hot trichloroacetic acid had produced increased staining with methods for demonstrating lipids, fatty matter could be extracted from the tissues. This demonstrates that the cells which gave the ‘spurious’ reaction did contain lipid. Hence it seems probable that extraction with solvents does not remove all lipids but may make those that remain more availabel for staining, so giving rise to what has been considered to be a spurious reaction.

The nature of the binding of lipid to protein and the relevance of such complexes to histochemistry and the composition of nuclei are discussed.
Neurosecretory Cells in the Abdominal Ganglia of Larvae of Lucilia caesar (Diptera)
Authors: Fraser Alastair
Published: April 2021

Ten neurosecretory cells can be found in each of the first 5 abdominal ganglia of the larva of L. caesar L. These are arranged as two lateral pairs and a single ventral cell in each half of a ganglion. Half the lateral cells go through a cycle of secretory activity before pupation in developing larvae. In diapause larvae while half the lateral cells are in a resting phase the remainder are in various stages of secretory activity. The destination of the product is not known. Chemically this product is, unlike that of brain neurosecretory cells, PAS-positive. It may contain a glyco-or phospholipid or lipoprotein component.
The Connective Tissue Sheath of the Locust Nervous System: A Histochemical Study
Authors: Ashhurst Doreen E.
Published: April 2021

The connective tissue sheath surrounding the nervous system of Locusta migratoria has been studied histochemically. It consists of an outer non-cellular layer, the neural lamella, and an inner layer of cells, the sheath-cells.

The neural lamella has been identified as being composed of a collagen-type protein and neutral mucopolysaccharide on the evidence of its histochemical reactions and the identification of hydroxyproline by paper chromatography in a hydrolysate of the neural lamella.

The sheath-cells possess large numbers of lipochondria composed of phospholipids and cerebrosides, and small spherical mitochondria. The cytoplasm also contains lipids (some of which may be cerebrosides), glycogen, and RNA.
Histochemical Studies of Herpetomonas muscarum
Authors: Dutta G. P.
Published: April 2021

The cytoplasm of the ‘leptomonas form’ of Herpetomonas muscarum contains a parabasal body, mitochondria, and so-called ‘volutin’ granules. The parabasal body consists of neutral lipid (probably triglyceride), lipoprotein, and DNA. The mitochondria are in the form of granules. The volutin granules are more numerous and smaller than the mitochondria. The volutin granules appear to be composed of ribonucleoprotein. Glycogen is dispersed homogeneously in the cytoplasm. The cytoplasm is rich in RNA and protein. The nucleus is DNA-positive. Near the parabasal body lies a basal granule; a long flagellum arises from it. A flagellar vacuole lies near the base of the flagellum.
A New Method for Staining Connective Tissue Fibres, with a Note on Liang’s Method for Nerve-fibres
Authors: Owen G.
Published: April 2021

A new method of staining connective tissue fibres is described. The stain used is alcohol-soluble aniline blue (spirit blue), after oxidation with potassium permanganate. The method is rapid and easy in application. Liang’s method for staining nerve-fibres is discussed briefly and its use in demonstrating the excretory system of Fasciola described.
The Central Nervous System in Larval Acraniates
Authors: Bone Quentin
Published: April 2021

This paper describes a part of the organization of the spinal cord of the larva of the Acrania, dealing chiefly with those tracts and cell groups that are probably concerned. with the control of the swimming pattern.

These observations serve as a basis for the comparison of the organization of the cord of the larva with that of the adult, and with that known for the larvae of the Agnatha and higher vertebrates. Other observations are concerned with the arrangement of the peripheral nervous system, which differs in some respects from that of the adult. The first section deals with the arrangement of the fibre tracts in the cord, and of the cell-bodies which give rise to these fibres.

The form and connexions of the giant cells are then described; it is shown that these cells are equivalent to the Rohon-Beard sensory cells of vertebrate embryos. They send peripheral processes out through dorsal root nerves, but they differ from the vertebrate sensory neurones in their greatly enlarged dendrite field and the longitudinal axon in the cord.

Thirdly, the innervation of the gill musculature is described. A ventro-lateral asymmetrical nerve is found, formed by the junction of fibres from the right anterior dorsal root nerves.

Lastly, the arrangement of the whole system is discussed in relation to the systems found in the larval stages of other primitive chordates.
The Use of Fixed and Stained Sections in Quantitative Studies of Peripheral Nerve
Authors: Williams P. L. , Wendell-Smith C. P.
Published: April 2021

A technique which has been widely used in quantitative studies of peripheral nerve involves fixation in Flemming’s fluid, embedding in paraffin wax, and staining with haematoxylin. An appraisal of the size changes induced by a standardized form of this technique has been made. Observations have been confined to changes in the thickness and external diameter of the internodal compact myelin sheath of the non-fasciculated nervus gastrocnemius medialis of the adult rabbit.

For a comparison of external diameters, sections from adjacent parts of the chosen nerve were prepared (a) by the standardized Flemming-Wolter technique; (b) by the rapid freezing technique, previously shown to reproduce accurately the dimensions present in fresh teased unfixed nerve-fibres. There was no significant difference in distribution of external diameters between sections prepared in the two ways.

For a comparison of sheath thicknesses, a regression line of 2 × myelin sheath thickness on external diameter was derived from each type of preparation. As external diameter was not appreciably affected by processing, a direct comparison of these regression lines could be made. It was found that regardless of external diameter or original sheath thickness, processing caused a reduction of sheath thickness of some 20% as a result of increase in internal diameter. This latter increase ranged from about 50% to under 20% with increasing fibre size.

Single frozen sections were passed through the series of reagents used in the Flemming-Wolter technique and photographed after each of seven stages. The principal changes in sheath thickness occurred in the first and last stages of processing. External diameter was not appreciably affected whereas the internal margin of the sheath was extremely labile. Observations suggest that slight inconsistencies in technique may be accompanied by relatively gross errors when measurements are undertaken. All stages need careful standardization, the most important in this respect being fixation, differentiation, final dehydration, and photographic exposure.
The Cytoplasmic Inclusions of the Neurones of Crustacea
Authors: Malhotra S. K.
Published: April 2021

Those who have studied the neurones of Crustacea have given very- divergent accounts of the ‘Golgi apparatus’ of these cells. Poluszynski (1911) described only short, straight or slightly sickle-shaped threads; he considered them as the Golgi apparatus. Monti (1915) believed that the Golgi apparatus of this cell was constituted by the mitochondria. She thought that they were long, wavy threads, which were blackened by the Golgi methods and formed a reticulum of the type seen in the neurone of vertebrates. Ross (1922) described a framework of ‘trophospongium’ connected with the surface of the cell. He thought this was additional to a reticular ‘Golgi apparatus’.
The Histology and Activities of the Tube-feet of Antedon bifida
Authors: Nichols David
Published: April 2021

The histology of the tube-feet and adjacent parts of the water-vascular canal of the crinoid Antedon bifida is described. The tube-feet possess the same basic structure as other, better-known tube-feet; here, however, they are adapted to collect food particles. They shoot out mucus by means of special muscle-operated glands and bend rapidly inwards to waft the mucus with entrapped particles into the food-grooves. The protraction of the tube-feet is probably brought about by a mechanism very similar to the ampulla system of other extensile tube-feet, but here the contraction of restricted portions of the water-vascular canal provides the necessary hydrostatic pressure.
A Study of Potassium Permanganate ‘Fixation’ for Electron Microscopy
Authors: Bradbury S. , Meek G. A.
Published: April 2021

The action of buffered potassium permanganate as a fixative for electron microscopy has been investigated. Electron contrast has been shown to be produced by the deposition of granular material in the tissue. The particles are about 50 A in diameter. Actual fixation of the tissue is performed by the dehydrating alcohol.

Histochemical studies have shown that RNA and histones are removed, whereas phospholipid-protein complexes are ‘unmasked’. The reaction of the permanganate with unmasked protein gives rise to high membrane contrast in electron micrographs.
The Demonstration of Glycogen in Liver Cells fixed in Osmium Tetroxide
Authors: Foster C. L.
Published: April 2021

Glycogen can be demonstrated histochemically in mammalian liver cells fixed in osmium tetroxide and embedded either in gelatine or in media used in electron microscopy. The form and distribution of the glycogen correspond very closely with those of structures seen in electron micrographs and which have been presumed to be glycogen.

Evidence was obtained which suggests that the glycogen occurring in some cells as small particles is probably not associated with mitochondria.
The Chorionic Plastron and its Role in the Eggs of the Muscinae (Díptera)
Authors: Hinton H. E.
Published: April 2021

In flies of the subfamily Muscinae the egg-shell has both an outer and an inner meshwork layer, each of which holds a continuous film of air. Between these two meshwork layers there is a more or less thick middle layer to which the shell chiefly owes its mechanical strength. Holes or aeropyles through the middle layer effect the continuity of the outer and inner films of air. Both meshwork layers consist of struts that arise perpendicularly from the middle layer. In both layers the struts are branched at their apices in a plane normal to their long axes. These horizontal branches form a fine and open hydrofuge network that provides a large water-air interface when the egg is immersed.

When it rains or when the egg is otherwise immersed in water, the film of air held in the outer meshwork layer of the shell functions as a plastron. To be an efficient respiratory structure a plastron must resist wetting by both the hydrostatic pressures and the surface active materials to which it is normally exposed. The plastrons of all the Muscinae tested resist wetting in clean water by pressures far in excess of any they are likely to encounter in nature. The resistance of a plastron to hydrostatic pressures varies directly as the surface tension of the water, and the surface tension of water in contact with the decomposing materials in which the Muscinae lay their eggs is much lowered by surface active materials. These considerations seem to provide an explanation for the great resistance of the plastron of the Muscinae to wetting by excess pressures and for the paradox that the plastrons of these terrestrial eggs are more resistant to high pressures than are the plastrons of some aquatic insects that live in clean water.
Axon Structure and the Dictyosomes (Golgi Bodies) in the Neurones of the Cockroach, Periplaneta americana
Authors: Wigglesworth V. B.
Published: April 2021

The large axons in Periplaneta are composed of bundles of osmiophobe strands about 0·5 µ thick which fan out into the body of the nerve-cell. These strands are here termed ‘neurofibrils’; it is suggested that the dictyosomes (Golgi bodies) are concerned in their secretion.

The dictyosomes are well stained by the osmium and ethyl gallate method. Each dictyosome surrounds or is applied to an unstained canal which runs into the cytoplasm and is believed to be continuous with the ‘neurofibrils’ as defined. There are all intermediate stages between thin fusiform sheaths of osmiophil material around the ‘neurofibrils’ and the thick rings or cuffs which form the dictyosomes. The clear canals through the dictyosomes are arranged in the main concentrically around the nucleus in the body of the cell; they commonly converge upon the nerve-fibre in the axon cone.
Development of the Testis Tubule in the Fowl
Authors: Kamar Gamal A. R.
Published: April 2021

Three phases of tubule development can be distinguished in males of the Fayomi breed :

the first 12 weeks, when only slight increase in tubule diameter and cell count occurs. During this period two stages in spermatogenesis are to be found. from the 16th to the 24th week, when rapid increase in tubule diameter and cell count occurs, and all stages of spermatogenesis are present. Sexual maturity, judged by the appearance of the first spermatozoa in the seminiferous tubules, occurs at about 16 weeks and is associated with a rapid increase in the size of the testes. The increase in testis weight is due, however, to increase in length of the tubules rather than to increase in diameter. from the 24th to the 52nd week, when only slight changes occur in microscopical appearance.
The Spermatophores of Dolops ranarum (Crustacea, Branchiura): their Structure, Formation, and Transfer
Authors: Fryer Geoffrey
Published: April 2021

Sperm transfer in the genus Dolops involves the employment of spermatophores. In this respect the genus is unique within the Branchiura.

Proteinaceous wall material is secreted by arborescent spermatophore glands located in the carapace lobes of the male and is passed into a pair of long canals which terminate posteriorly as a pair of spermatophoric vesicles, part of whose walls are glandular. Spermatozoa from the vasa deferentia are injected into these vesicles and become surrounded by wall material. During the mating process the contents of each vesicle are squeezed out through the common genital orifice, where they become con- fluent and form a single, globular spermatophore. While its walls are still soft this is pressed against the base of the abdomen of the female, where it is pierced by two perforated spines at the end of the spermathecal ducts. The spermatophore hardens and remains attached to the female, thus giving the spermatozoa opportunity to migrate through the spermathecal ducts to the spermathecae. Not until after a moult of the female, however, during which the spermatophore is shed with the old cuticle, are the spermatozoa free to enter the eggs, each of which is believed to be pricked by the spermathecal spines during oviposition.

By virtue of the fact that it involves quite different organs and processes in the two groups, spermatophore formation indicates that the Branchiura and Copepoda are not closely related. On the other hand, the process is in no way suggestive of a close relationship of the Branchiura and Branchiopoda, and the isolated position of the Bran- chiura is emphasized.
Ester Wax 1960 : a Histological Embedding Medium
Authors: Steedman H. F.
Published: April 2021

A modification of the original formula (Steedman, 1947) is given which still retains the softness of infiltrated tissues. The section, both wax and specimen, flattens on water. The sections of a ribbon adhere during flattening. Adhesion of sections to the slide is good. The room temperature for successful ribboning may vary from 17° to 25° C or higher.
The Interstitial Cell in the Testis of the Foetal Sheep
Authors: Baillie A. H.
Published: April 2021

The testes of 18 foetal sheep, of crown-rump length from 2·8 to 40 cm, have been studied by the PAS, Sudan black, and plasmal tests. Typical interstitial cells differentiate from mesenchymal precursors; the nucleus alters first, becoming ovoid and vesicular; then the cytoplasm increases in amount, its processes become fewer and smaller, sudanophil lipid droplets appear, and the result is a lipid-laden epithelioid cell. Two atypical forms of interstitial cell have been noted: the first has groups of eosinophil granules in its cytoplasm, the second is shrunken and has a pycnotic nucleus. The interstitial cell of foetal sheep, unlike that of poikilotherms, contains no glycogen. The PAS-positive polysaccharide / protein granules found in the interstitial cells of adult homiotherms are absent from the interstitial cells of this foetal homiotherm. While sudanophil lipids appear at an early stage, Schiff-positive lipids (plasmalogens, acetal phosphatides, and possibly steroids) are entirely absent from the interstitial cells of the foetal sheep.
The Nerve-net of the Sea-Anemone Metridium senile : the Mesenteries and the Column
Authors: Batham E. J. , Pantin C. F. A. , Robson E. A.
Published: April 2021

The actinian nerve-net has been examined in the mesenteries and column of Metridium senile (L.) after staining with silver and with methylene blue. Modified staining methods are described. The synaptic nature of the junctions between bipolar nerve-cells, of their expanded terminations over the muscle-field, and of their contacts with the neurites of sense-cells is reviewed. The neurites always run in the space between the epithelium and underlying muscle. They follow the distribution of the main contractile systems, including the passage of circular fibres beneath the mesenteries. The richer innervation of the retractor surface of a mesentery compared to the radial is correlated with the ability of this hypertrophied muscle to contract rapidly. The distribution of nerve-cells and sense-cells in the mesenteries and column is related to physiological evidence concerning the through-conduction pathways, facilitated and slow contractions, and other aspects of the behaviour of Metridium. It is concluded that although features such as reciprocal inhibition in the column are still unexplained, there is as yet no histological or physiological evidence for double innervation of the muscles in this anemone. The terminations of sensory neurites, on musclefibres or elsewhere, have not yet been seen in any actinian.
The Chemical and Physical Nature of the Visible Regions of Mouse Ascites Tumour Cells, and of the Cells of Solid Tumours grown from them
Authors: Ross K. F. A.
Published: April 2021

A new technique was used to embed separate mouse ascites cells of 7 different strains in a supporting medium so that they could be sectioned, and a number of histochemical tests were carried out on this material. The results of these were in good general agreement with the findings of Love & others (1953, 1956), who investigated the histochemical properties of dried smear preparations of ascites cells of very similar strains; but certain important differences were found, notably the present investigation revealed the presence of phospholipid in almost all the lipid droplets in the cytoplasm. No important differences were found in the histochemical properties of the cells of the 7 different strains examined, nor between these and the cells of subcutaneous solid tumours grown from them.

The solid content of the cytoplasm, nuclear sap, and nucleoli of the living cells of 6 of these 7 strains were measured by immersion refractometry and interference microscopy. The mean total solids in the cytoplasm were, in all strains, near to 14% w/v and the concentration in the nuclear sap was usually a little lower than this. The total solid in the nucleoli was approximately 50% w/v. Intact living cells were also isolated from the solid tumours by means of a special ‘homogenizer’, and the total solid in their cytoplasm was in all cases identical with that of the ascites cells from which they were derived.

From these data it seems probable that the chemical and physical characteristics of many different strains of ascites cells, including those of carcinomatous, sarcomatous, and leukaemic origin, do not differ markedly from one another; and are also probably not very different from those of the cells of the solid tumours from which they were originally derived.