bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations and Experiments with the Microscope on the Effects of Prussic Acid on the Animal Economy
Authors: Shearman Ralph Thomas
Published: April 2021

Every year as it passes away leaves behind it additional testimony to the fact that the microscope is advancing to occupy a position of importance in medical practice equal to that which the stethoscope has attained ; and I feel satisfied that ere many more years have passed the regular employment of the microscope, as a means of diagnosis, will be maintained and duly acknowledged. The slow but steady progress which the use of this instrument has made in the hands of the medical profession should tend to point rather to the important nature of the results to which it is destined to lead us, than to accepting the doubts of some who occasionally assail its employment, and are unable or unwilling to avail themselves of its powers.
Description of the Peripheral Termination of a Motor Nerve
Authors: Moxon W.
Published: April 2021

In the spring of the year 1862 it chanced to me, in the course of observations upon the anatomy of insect larvæ, to light upon an example of a muscle on which the ending of a nerve can with certainty and exactness be seen.
Concerning some Little-known Forms of Animal
Authors: Mecznikow Elias
Published: April 2021

I publish the following remarks because, however deficient and incomplete they may be, yet they touch upon a number of interesting and almost forgotten animals whose natural history is so little known, that every fact that relates to them deserves attention.
On the Anatomy of Conus tulipa, Linn., and Conus textile, Linn
Authors: Shaw H. O. N.
Published: April 2021

SINCE 1895, few workers on the anatomy of mollusca have devoted their attention to the genus Conus. In that year Dr. Bergh (3) published an extensive memoir on a large number of species in this genus, and his work may be considered as the most complete, and embracing the greatest number of. species examined, though his description of each species was not exhaustive. Troschel (20) devoted most of his attention to the radulae of the different genera and species of which his excellent work is composed, and although he gives a certain number of figures with descriptions of various anatomical points, these latter are for the most part of rather a crude and diagrammatic kind.
A Further Study of the Mitotic Spindle in the Spermatocytes of Forficula auricularia.
Authors: Meek C. F. U.
Published: April 2021

The length of the spindle at the stage immediately preceding the conclusion of the primary spermatocyte metaphase is not a constant. The length of the spindle at the conclusion of the primary spermatocyte metaphase is not a constant, and is sometimes smaller than that observed at the stage immediately preceding the conclusion. The length of the spindle in the early primary spermatocyte anaphase is not proportional to the amount of chromosome divergence, and is sometimes smaller than the lengths observed at the stages mentioned in (1) and (2). The volumes of the primary spermatocyte cells vary in the metaphase. The length of the spindle at the conclusion of the primary spermatocyte metaphase is not proportional to the volume of the cell. The length of the spindle at the stage immediately preceding the conclusion of the secondary spermatocyte metaphase is not a constant. The length of the spindle at the conclusion of the secondary spermatocyte metaphase is not a constant, and is sometimes smaller than that observed at the stage immediately preceding the conclusion. The length of the spindle in the early secondary spermatocyte anaphase is not proportional to the amount of chromosome divergence, and is sometimes smaller than the lengths observed at the stages mentioned in (6) and (7).
Memoirs: The Chorda Tympani and Middle Ear in Reptiles, Birds, and Mammals
Authors: GOODRICH EDWIN S.
Published: April 2021

A comparison of the development of the various structures of the middle-ear region in the lizard, duck, and mammal, shows a remarkable uniformity in their origin and relation. The first gill-pouch separates off from the epidermis from below upwards; at its dorsal edge is an epiblastic proliferation contributing to the geniculate ganglion. The tympanum is formed between the outer epidermis and an outgrowing diverticulum of the hinder lower region of the first gill-pouch. The chorda tympani is a post-trematic branch of the facial nerve, developing behind the first or spiracular gill-slit, and passing down to the lower jaw between the tympanum and the closing spiracle. The relation of these parts to the skeleton and blood-vessels is (with the exception mentioned below) constant throughout the Amniota, and is only intelligible on the view of Reichert that the proximal region of the columella corresponds to the stapes, the quadrate to the incus, and the articular to the malleus.

In the chick the chorda tympani develops as a pre-trematic branch of the facial nerve from its first appearance. In adult gallinaceous birds the chorda passes down directly from the geniculate ganglion in front of the tympanic cavity. This exceptional position is probably due to some secondary modification at present unexplained.
The Placenta of a Lemur
Authors: Jenkinson J. W.
Published: April 2021

Our knowledge of the placentation of the lemurs begins with the publication, in 1875, by A. Milne-Edwards and A. Grandidier, in their Historio naturelle des Maminifères de Madagascar/ of an account of the placenta in Propithecus and some other forms.
Notes on the Morphology of Bathynella and some Allied Crustacea.
Authors: Calman W. T.
Published: April 2021

The recent re-discovery of Bathynella nutans by P. A. Chappuis (1914A, 1915)1 throws welcome light on one of the most remarkable of living Crustacea. In the thirty years that had elapsed since its first description by Vejdovsky (1882), from two specimens found in a well in Prague, this minute form had not been obtained by any other naturalist. Some eighteen years ago a re-examination of the solitary remaining specimen enabled me, in spite of its poor state of preservation, to add some details to Vejdovsky’s account, and led me to the conclusion that it was allied to An aspides (Caiman, 1899). The scantiness of information regarding it, however, has caused most writers who have had occasion to refer to Bathynella in text-books or elsewhere to suspend judgment as to its affinities, and the late Geoffrey Smith (1909) omitted it altogether from his revision of the Anaspi-dacea. The detailed account of its structure now provided by Chappuis from the specimens found in Switzerland entirely confirms my earlier conclusions as to its systematic affinities, and enables us to say that Bathynella is undoubtedly a degenerate member of the Syncarida, a group of Crustacea which has persisted from Carboniferous times, and of which the only other living representatives are found in Australia and Tasmania.
Polyembryony in Parasitic Hymenoptera : A Review.
Authors: Gatenby J. Bronté
Published: April 2021

Among the specially remarkable facts in the study of embryology that of polyembryony or germinogony in Parasitic Hymenoptera is not the least noteworthy. Polyembryony consists in the production from one single egg, by a process of gemmation, of a large number of separate embryos. Polyembryonic species of Hymenoptera are known from the Chalcididæ and the Proctotrypidæ ; many of these insects are jet black or brownish creatures about 1 or 2 mm. in length, with gaudily sheeny wings and bodies ; in many cases they are so small as to be almost invisible to the naked eye, in others these insects are much larger, but British species above 5 mm. in length are not common.
The Pseudopodia of the Leucocytes of Invertebrates
Authors: Goodrich Edwin S.
Published: April 2021

It is to Wharton Jones that we owe the first comprehensive account of the leucocytes in the various groups of Invertebrata : in an important paper, published in 1846 (6), he described and figured them as of “stellate appearance,” and sometimes as shooting out “cilia-like processes.” Since then numberless authors have studied these cells and pictured them as provided with free outstanding pseudopodia. Evidence is brought forward in this paper that the spiny appearance of leucocytes is of the nature of an optical illusion or due to changes taking place under abnormal conditions, that freely projecting fine processes are seldom, if ever, produced in the fluids of living invertebrates, and that the pointed pseudopodia so often figured are merely the optical sections of delicate, more or less folded films.
On the Classification of Actiniaria: Part I.—Forms with Acontia and Forms with a Mesoglœal Sphincter
Authors: Stephenson T. A.
Published: April 2021

Whilst working out recently the species contained in two collections of Actiniaria (the “Terra Nova” collection (79)1 and one made by the Irish Fisheries Department (80)) , I have been led to develop certain views on Actinian classification. Some of the families of Actiniaria are defined by only a small number of the more important characters possessed by the contained forms, with the result that some of them (e. g. Uyanthidæ, Sagartiidæ, Paractidæ) represent not so much families as series of forms, each series including a number of animals which differ among themselves in ways so important as to be fundamental, although presenting a few common features. This arrangement neither represents the natural affinities of the genera nor does it throw much light upon their evolutionary history. It is often difficult also to allocate new species and genera to their correct position, because in a good many cases sufficiently precise generic definitions have not been arrived at. I have therefore thought it would be the best thing to set out for what they are worth the ideas I have developed during the course of my work. I have as yet applied them in detail to only one particular portion of the Actiniaria, and that application constitutes the following paper. I have begun with the group of forms belonging to the Actiniina which possess acontia or mesoglœal sphincters, because the collections I have been working at happened to present a preponderance of those forms ; I am also well acquainted with some living members of it. I am hoping in due course to work out schemes on similar lines for the classification of those Actiniina not included in the present paper and of the Stichodactylina. As yet, however, I have made only a beginning on the two latter groups, so am publishing the finished section at once. More work on these two groups may throw fresh light on various Actinian problems, but is not very likely, I think, to affect the section dealt with in this paper to any extent.
The Eye of Peripatus.
Authors: Dakin William J.
Published: April 2021

The first description of the minute structure of the Eye of Peripatus was given by Balfour (1) in his memorable paper on the anatomy of Peripatus capensis. So far as I am aware nothing has been added to our knowledge of the structure since that date, despite the advances in microscopical technique, and the rather therough investigation of invertebrate visual organs. Other arthropod eyes have received considerable attention, and this seems strange at first because a comparison of the Peripatus eye with that of other arthropods should be highly interesting by reason of the phyletic position occupied by the Onychophora.
Review
Authors: Gatenby J. Bronte
Published: April 2021

This eighth edition of Mr. Bolles Lee’s well-known Microtomist’s Vade-Mecum has been edited and entirely revised by Professor J. Bronte Gatenby with the assistance of five collaborators.
Studies on Insect Spermatogenesis: V. On the Formation of the Sperm in Lepidoptera
Authors: Bowen Robert H.
Published: April 2021

In a paper published several years ago by Gatenby (1917 a) an account of sperm formation in Lepidoptera was given, certain features of which departed rather widely from the results of previous workers on similar material. Particularly interesting from my own point of view were the descriptions of the origin of the acrosome and the history of the mitochondria (‘macromitosome’ or nebenkern) in the spermatid, these matters having proved especially difficult to elucidate in the Hemiptera upon which I had resumed work early in 1919. As this work progressed, it became increasingly evident that the facts in the Hemiptera (and in other forms which I have studied subsequently) did not agree with certain important features of Gatenby’s account, and aroused the suspicion that perhaps the facts in the Lepidoptera might be open to a somewhat different interpretation. I decided accordingly to put up some lepidopteran material for purposes of comparison, and during the last three years this has been done whenever opportunity offered. Considerable difficulty was encountered, due to the impossibility of accurately determining the age of pupae from their external appearance, and a proper range of preparations was therefore not easy to obtain. Certain stages are in fact still incomplete, but the general features are now sufficiently clear to permit comparisons with other insects and it did not seem worth while to pursue the matter further at present. This paper will deal, therefore, only with the mitochondria and Golgi apparatus (‘acroblasts’), and with them particularly in the older spermatids.
On Sexual Differentiation In The Infusoria
Authors: Dogiel V. A.
Published: April 2021

The object of this preliminary note is to describe a very curious type of conjugation which may throw light on the process of sexual differentiation in the Infusoria—a type leading from conjugation between two hermaphrodite individuals to copulation between male and female specimens. In his very lucid account of the genetics of the Ciliata, C. Dobell (1914),x with good reason, points out that in cases of typical conjugation both the conjugants are to be looked on as hermaphrodites which are performing cross-fertilization. Only in Vorticellids there are males and females, and the sexual process changes to copulation, while the dwarf-like male perishes after fertilizing the larger female. In other Ciliata there are no well-proved cases of sexual differentiation of the conjugants, although some hints at it are to be found in the works of Cull, Doflein, and Enriques. Doflein states that the conjugants of the same pair in Paramecium putrinum differ very much in size, a feature which he is ready to attribute to sexual differentiation. Enriques relates of Chilo don that the conjugants, which are very much alike at the beginning of conjugation, become differentiated into a longer and a shorter one during the process of conjugation. The meaning of such conjugants—termed by Enriques ‘male and female hemisexes ‘—remains obscure, as also the extensive discussion of the author on the subject of sexual differentiation. The observations of Cull on ‘incipient sexuality ‘in Paramecium proved to be erroneous (Jennings and Lashley), and need no further mention. But in this paper I propose to describe a case of conjugation in the Ciliata where the members of a pair show very marked differences, which may have a relation to sex.
Sanguinicola From The Sudan
Authors: Woodland W. N. F.
Published: April 2021

In 19081 the description by Dr. Marianne Plehn of Sanguinicola as the only known example of a Cestode (Cestodarian) infesting the blood aroused considerable interest, and though the subsequent conclusion by Odhner in 19112 that Sanguinicola was rather to be regarded as an extreme form of suckerless haematobic Trematode somewhat detracted from the significance of the discovery, yet on account of its plesio-Turbellarian structure and possible Turbellarian affinities, Sanguinicola still remains a zoological type of importance.
On Centropygus joseensis, a Leech from Brazil
Authors: Badham Charles
Published: April 2021

During the Percy Sladen Expedition to Brazil in 1913 Professor J. P. Hill collected six specimens of land leeches, and while I was on leave from the Australian Imperial Force in France, and acting as Demonstrator in his department, he requested me to describe them. I was glad of this opportunity, for these leeches, themselves earthworm-like in appearance, were easy to determine as close relatives of Lumbrico-b d e 11 a, that interesting leech from Brazil, which has so closely copied the form and habit of an earthworm.
The Relation of the form of a Sponge to its Currents
Authors: Bidder G. P.
Published: April 2021

All zoologists know that from the large holes, which we call oscula, on a sponge, an outgoing current may be detected in life. During several months in Naples I investigated this current, using litmus and carmine solutions, and carmine and indigo in suspension. I worked with two calcareous species of sponges, having oscula at the end of tubular prolongations, which reach the size and shape of a child’s thumb in the case of Leucaltis, and of a child’s finger in the case of Leucandra aspera (Text-fig. 1). The solutions were either placed on the surface of the sponge, to be sucked in by its currents (Text-fig. 2), or dropped by a pipette through an incision into the cloaca—the cavity of the tubular prolongation. In the latter case the time taken for the colour to be thrown out at the osculum, though liable to many corrections, afforded on the whole the most trustworthy determinations of oscular velocity: the cloaca being wider than the osculum, the observed cloacal velocity would be multiplied by 4, 5, or 6, as the case might be, to obtain the oscular velocity. A pretty method was arrived at accidentally (Text-fig. 3), when I found the coloured jet marked by dark beads or nodes, caused by my pulse shaking the pipette; the length between any two nodes, divided by three-quarters of a second, gives the core-velocity at that part of the jet.
The Golgi Bodies of a Coccidian
Authors: King Shana D. , Gatenby J. Brontë
Published: April 2021

For many months we have been collecting material of the protozoan fauna of the gut of Lithobius forficatus. Our object was to study the Golgi apparatus, if such were present, and to examine also the behaviour of the mitochondria. We chose the form Adelea because we believed that its lifehistory was well known, and that there would be no special difficulty in identifying the stages. In this we have been disappointed—we found that Siedlecki and other workers have left the matter in a confused state : we have been obliged to spend many months trying to piece together the various parts of the life-history : at present we are not sure of any of the stages except those described in this paper.
Some Observations upon Spirostomum ambiguum (Ehrenberg)
Authors: Bishop Ann
Published: April 2021

The genus Spirostomum was first mentioned by Ehrenberg, but no definition nor description was given. Its systematic position and the question of the number and identity of the species contained in it was a subject for discussion for many years. Later, Dujardin (7) gave a very satisfactory description of the genus in the following words :
Head Length Dimorphism of Mammalian Spermatozoa
Authors: Parkes A. S.
Published: April 2021

Chromosome dimorphism of the spermatozoa has been shown for a variety of mammals, and in some cases this has been shown to be correlated with dimorphism in the head lengths of the spermatozoa. In the present paper this correlation has been extended to the spermatozoa of man, the mouse, and the rat, in which chromosome dimorphism of the spermatozoa had previously been shown, and in which head length dimorphism seems to exist. The interest of these results lies in the probability that the histological difference in the X- and Y-spermatozoa may account for the inequality of the sexes at conception in mammals.
On Brinkmann’s System of the Nemertea Enopla and Siboganemertes Weberi, n.g.n.sp.
Authors: Stiasny-Wijnhoff Dr. Gerarda , Leiden
Published: April 2021

All text-books of zoology give the Nemertean system as Bürger published it several times in his monographs on this subject (6, 7, 8). The old systems of Schultze, McIntosh, Hubrecht have been forsaken, and our textbooks do not divide the Nemertini any more in Anopla and Enopla, or Palaeonemertea, Hoplonemertea, and Schizonemertea. The armature of the proboscis and the arrangement of the cephalic slits are believed to be of secondary importance, and Bürger divided the Nemertini into four orders, three of which, his Protonemertini, Mesonemertini, and Metanemertini are supposed to be closely related by having a body-wall that consists of an epithelium, a basement membrane, and two muscular layers. Benham, in Ray Lankester’s ‘Treatise on Zoology ‘, unites them as Dimyaria, and his Trimyaria consist of one order only, the Heteronemertini Burger. The Protonemertini are McIntosh’s family Carinellidae, Mesonemertini are his family Cephalotricidae and the genus Carino ma (Hubrecht) ; Metanemertini is a new name for Hoplonemertini (Hubrecht) or Enopla (Max Schultze), and Heteronemertini are Hubrecht’s Schizonemertini and his families Eupoliaidae and Valenciniaidae. Everybody agrees that the last two families are more nearly related to Lineids and Cerebratulids than to the Protonemerteans, and their enclosure in the order Heteronemertini seems to be well founded. The following schema gives the synonyms in the different systems.
Notes on Sporozoa parasitic in Tubifex: 1. The Life-history of Triactinomyxon Štoic
Authors: Mackinnon Doris L. , Adam D. Ines
Published: April 2021

The Thames mud below Waterloo Bridge is full of reddish masses of small interlaced worms ; these are the oligochaetes Tubifex tubifex (Müll.) (= T. rivulorum Lmk.) and Limnodrilus hoffmeisteri Clap. While examining their gut-contents we found in Tubifex three species of that rare and little-studied organism Triactinomyxon Štolc, and having such large quantities of the host at our very doors we continued our search in the hope of elucidating some parts of the life-history.

Though we dissected 1,250 Tubifex we found the actinomyxidian only five times. This is approximately in agreement with Štolc’s statement that only one worm in 300 is infected. In three worms the infection was heavy, and in the other two it was comparatively light.1
On a new Prorhynchid Turbellarian from Tasmania
Authors: Hickman V. V.
Published: April 2021

1. Prorhynehus tasmaniensis sp. nov. is found under alpine conditions in Tasmania.

2. It is allied to Prorhynehus putealis Haswell, but exhibits the following differences: (a) Larger size, (b) Posterior excretory canal does not bifurcate, (c) Female genital pore almost in line with excretory pores and below pharynx, (d) Female genital pore only one-eighth of body-length from anterior end. (Difference from all other members of the genus.) (e) Germo-vitellarium in middle line ventral to intestine. (f) Testis follicular, extending from the right side over the intestine on to the left side. (Difference from all other members of the genus.)
Note on the Amoeboid Elements in the Blood of Helix aspersa
Authors: Haughton Isabel
Published: April 2021

Recently a considerable amount of work has been carried out in this laboratory by Gatenby, Duthie, Hill, and Macdougald on invertebrate tissue culture (4, 5, 6, 7, 8). Bohuslav also figured growths from various organs of Helix (1), notably the atrium (2). As the work quoted above has been done with species of Helix only, it is desirable at this point to notice and compare the behaviour of the leucocytes in the blood of Helix aspersa. Kollmann (12), by his comparative studies, demonstrated the homology of the leucocytes in all groups ; there is, therefore, no reason to suppose that the cell elements found in the blood are other than leucocytes.
Epiphysial Growth in the Branchial Skeleton of Fishes
Authors: Wheeler Haines R.
Published: April 2021

The branchial bones of several bony fishes were studied in longitudinal section, and in one case a reconstruction model was made. A massive cartilaginous epiphysis lies partly enclosed within the shaft of the bone and partly beyond it. In the cartilage there can be distinguished a zone of undifferentiated cells lying beyond the bony shaft, a proliferative zone of flattened cells at the level of the end of the shaft, and a zone of hypertrophied cells no longer undergoing division enclosed within the shaft. In some cases there is a secondary centre of calcification in the zone of undifferentiated cells.

The mechanism of growth of the epiphysis and the formation of endochondral bone are similar to those found in the long bones of tetrapods, but in their details they are more simple in the fish.
Some remarks on North Atlantic Non-Pelagic Polystylifera
Authors: Stiasny-Wijnhoff Gerarda
Published: April 2021

This publication contains the description of three previously but insufficiently known representatives of the former genus Drepanophorus, that live in the northern Atlantic Ocean. They are, together with the two species of Uniporus described by Brinkmann (1913), the only Beptantia that are known from the Atlantic. One of them, Punnettia splendida, lives in the English Channel, and was described by Keferstein and McIntosh as a distinct species, different from Hubrecht’s Drepanophorus rubrostriatus. Bürger included all these species in the Mediterranean D. spectabilis, and so did Riches and the author. After my publication on Mediter- ranean Polystilifera (1926), in which the Atlantic species as being separate was not mentioned, the late Professor McIntosh asked why I had been silent on this question. The present article gives my answer. The material has partly been collected by me in Plymouth, and partly consists in a series of sections from Professor Brinkmann.
The Germ-Cell Cycle in Phytophaga destructor Say
Authors: Metcalfe Margot E.
Published: April 2021

The somatic cells in both sexes of Phytophaga destructor Say contain four pairs of V-shaped chromosomes, the sex-group being indistinguishable in size or form. The germ-cells in both sexes contain eight pairs of chromosomes. The maturation of the egg follows the normal course of development, eight bivalents being formed. After polar body formation the female pronucleus has eight chromosomes. The polar bodies are never extruded from the egg. Spermatogenesis is a complicated process, the details of which have not been satisfactorily determined. The growth stage appears to take place before the last spermatogonial division. No pairing of chromosome has been observed, and apparently no metaphase plate is formed at meiosis. Reduction is effected by the expulsion of two buds each containing four chromosomes. Thus only one sperm is produced from each spermatocyte. One or more sperms may enter the egg at fertilization. The germ-line is differentiated from the soma at the eightcell stage. At the fifth cleavage the somatic nuclei eliminate half their number of chromosomes, and are left with eight chromosomes. Migration of the germ nuclei takes place at the sixteencell stage. The relation of the chromosome numbers in the somatic and germ lines is discussed.
On the Formation of the Ground Substance of Loose Connective Tissue
Authors: lasswoin G.
Published: April 2021

The formation of the ground substance of connective tissue has for long been one of the most controversial problems of histology. In spite of the diversity of the material studied, and of the methods of investigation used, there exists on this problem as yet no generally accepted view. Thus, we have at present several theories treating differently of the process of the formation of the ground substance and of its fibres.
The Spermatogenesis of Stenophylax stellatus, Curt. (Trichoptera)
Authors: Gresson R. A. R.
Published: April 2021

The structure of the nuclei of the spermatogonia, spermatocytes, and the nuclear changes during the division of the spermatocytes are described. The nucleolus of the spermatocytes of Stenophylax does not contribute directly to the formation of the chromosomes as claimed by Lutman (8) for Platyphylax designatus. The diploid chromosome number of Stenophylax stellatus is sixty. The Golgi material of the spermatogonia and of the early primary spermatocytes is in the form of a dense mass; in the primary spermatocytes this mass separates to form two masses. The Golgi material of the spermatogonia and spermatocytes breaks up to form Golgi bodies which move towards the poles of the spindle, and are thus distributed with approximate equality to the resulting cells. Granular mitochondria are present in the spermatogonia; during the metaphase they are distributed throughout the cytoplasm. During the division of the spermatocytes the mitochondria come together to form two masses at the side of the spindle; in the telophase these masses are separated into two approximately equal parts. The acrosome is formed under the influence of some of the Golgi material; after its formation the Golgi material breaks up into smaller bodies which become distributed through the tail region. The mitochondria, in the form of a tangled mass of filaments, become arranged around the axial filament; later they form a compact sheath. A vesicle makes its appearance in the nucleus of the young spermatid and increases in size, but later becomes smaller and finally disappears. A structure which is probably a post-nuclear body was observed in the young spermatid.
The Embryonic Development of the Stick- Insect, Carausius morosus
Authors: Thomas A. J.
Published: April 2021

The maturation of the egg takes place in the ovarian tube, and is immediately followed by the formation of the cleavagenucleus and its division into many nuclei. The entire products of the cleavage-nucleus migrate to the surface to form the blastoderm. Cleavage of the yolk was not observed even in late stages. Yolk-cells are absent when the blastoderm is being formed. Primitive endodermal cells are proliferated from the middle of the germ-band, and form a membrane between the germ-band and the yolk. The membrane is present only in embryonic stages ; some of the cells proliferated wander into the yolk and act as vitellophags. Mesoderm is formed by proliferation of cells from the ventral plate. It is preceded by the formation of a shallow gas- trular furrow, and from the bottom of this furrow proliferation takes place. The mesoderm becomes arranged in segmental masses. Two masses of cells proliferated at the anterior and posterior ends of the germ-band are shown to be the endodermal rudiments from which the mid-gut epithelium is formed. The invaginations of the stomodaeum and proctodaeum grow against these masses and carry parts of the proliferating areas near their blind ends. It is shown that the various methods of mid-gut formation which have been described could be reconciled with the process described in Carausius. The hinder end of the mid-gut is flanked by two plates of ectoderm which are forward extensions of the proctodaeum. Into these extensions the Malpighian tubules open, and, as their histology is identical with that of these extensions and widely different from that of the mid-gut, these tubules must be ectodermal in nature. The formation of the amnion and serosa are described.
On the Nature of the Free Cell-Border of certain Mid-Gut Epithelia
Authors: Newell G. E. , Baxter E. W.
Published: April 2021

The terms cilia, rod-border, brush-border, and other terms used in this paper are defined. The epithelium lining the mid-gut of Melinna is described with special reference to the cell-border. Variation between different regions of the gut are noted. There are two main types of epithelia: (i) ciliated, (ii) rod-bordered. The presence of a peritrophic membrane in the middle region of the stomach is noted. A description of the mid-gutepithelium of Locust a and Chironomus is given, and the essential similarity between the brush-borders of the two is stressed. The ciliated effect described by Vignon in Chironomus is shown to be due to the presence of motile bacteria. From a thorough survey of the literature and from our own observations, it is concluded that there are two main types of cell-borders: A. Motile, i.e. ciliated; with which basal corpuscles, derived from division of the centrosomes, are always associated.B. Non-motile.—It is held that these are of two distinct types: (i) Rod-border, where the elements are probably homologous with the basal segments of cilia. This type occurs in Melinna, Lumbricus, and probably in other animals, and it is possible that the striated free border found in the epithelium of the vertebrate intestine is of a somewhat similar nature.(ii) Brush-border, where the elements are simple filaments and bear no relation to cilia. This type is found typically in insects and in a slightly modified condition in the uriniferous tubules of vertebrates. Both motile and non-motile elements lie above the free surface of the cell which is marked by the limiting membrane. Mention is made of the brush-border epithelium of the Malpighian tubules of insects.
The Effect of Ultra-Centrifuging Vertebrate Neurones
Authors: Brown R. H. J.
Published: April 2021

The Golgi apparatus may appear as a network or incomplete reticulum; it is lighter than the other cytoplasmic inclusions but its form makes its displacement difficult. Its parts never approach the periphery of the cell. The neutral-red bodies have no part in its composition. There exists a separate canalicular system which is connected with the surface of the cell, and otherwise is of similar dimensions to the Golgi apparatus. It is thought to represent the trophospongium of Holmgren. It is unaffected by the centrifuge. The vacuome appears in the form of isolated granules which can be osmicated after staining in neutral red. They are lighter than the cytoplasm and are separate from the Golgi apparatus, though on account of their similar density they are thought to have some spatial connexion with it. The mitochondria are in the form of rods and granules which are very slightly denser than the cytoplasm, and show no evidence of having any connexion with the Golgi apparatus. The Nissl substance occurs as large irregular bodies in the fixed material. It is thought to be in a diffuse form in the living cell. It is much denser than the cytoplasm.
Two Polymastigote Flagellates of the Genera Pseudodevescovina and Caduceia
Authors: Kirby Harold
Published: April 2021

The previously published description of Pseudodevescovina uniflagellata from Kalotermes (Neotermes) insularis is incorrect in practically all points. The flagellate is a devescovinid which, like other members of the subfamily, has three anterior and one trailing flagellum. The trailing flagellum is relatively small and slender. The most unusual characteristic is the parabasal apparatus, which consists of a C-shaped or L-shaped main limb adjacent to the nucleus and seven to nineteen cords attached to the transverse portion of this. A sinuous movement of the cresta has been observed in living material. The flagellate moves forward steadily with considerable vigour as compared to Devescovina lemniscata and even Stephanonympha with its hundreds of flagella. Yet the small trailing flagellum seems to be the main cause of this movement, as the anterior whip often is turned back against the body and trailed. This suggests that increase in size of the trailing flagellum, which is a broad ribbon in Devescovina lemniscata, or increase in number as in Stephanonympha, does not necessarily enhance the locomotor efficiency of the flagellate. The body is completely covered with a dense investment of relatively short spirochaetes, the ends of which appear actually to be embedded in the cytoplasm and, taking an iron-haematoxylin stain, simulate basal granules. There are eight chromosomes, which can be recognized most clearly when they are granules or short, stout rods in the early telophase. At the beginning of binary fission, the main limb of the parabasal apparatus breaks. A portion of length about equal to that of the nucleus is left attached to the centriole at one pole of the spindle; at the other pole a parabasal develops d e novo, doubtless in connexion with the centriole. This is at first a filament, which reaches a size equal to the part of the old parabasal that remains attached, then both grow equally. After division of the body, new cords grow out from this main limb. The detached part of the old parabasal apparatus breaks up into successively smaller vesicular bodies, which are noteworthy for a deeply staining cap sharply distinguished from the chromophobe substance, appearing like diagrams of dictyosomes. These fragments are resorbed before plasmotomy. Grassi’s Devescovina nova has been found in the species of termite from which he described it, Kalotermes (Neotermes) erythraeus from Eritrea. Its characters indicate that it must be removed from Devescovina, and it has been placed in the genus Caduceia. The parabasal apparatus consists of a main limb, which in this case is loosely spiralled around the trunk of the axostyle, and from one to six attached cords directed more or less parallel to it.
On the Ciliary Mechanisms and Interrelationships of Lamellibranchs: PART IV: Cuticular Fusion, with special reference to the Fourth Aperture in certain Lamellibranchs
Authors: Atkins Daphne
Published: April 2021

A form of fusion involving only the cuticle has been found in certain Lamellibranchs between the outer demibranchs and the mantle or the visceral mass; between the two inner demibranchs; and, in forms possessing a fourth aperture, between the mantle lobes in the mid-ventral line between this and the pedal aperture. The histological structure of the junction is described, and is especially considered in relation to the condition of the fourth aperture in the Solenidae.
Microscopic Illumination
Authors: Smith Edwin
Published: April 2021

It is often difficult to obtain an equally illuminated field for both eyes when a half-inch object-glass is employed with the binocular. The prism causes the field to be darkened on opposite sides for the two tubes of the body. This defect becomes more apparent when the lenses of the object-glass are further separated from the prism by the additional thickness of the nose-piece. Diffusing the light with ground glass partly remedies the defect, but not entirely; moreover, diffused light is not suitable for many objects, where definite shadows are desired for the purpose of displaying structure. I find, however, that an achromatic combination with wide aperture as condenser, and a half-inch mounted in short cells, completely satisfy the conditions of the problem, and I am now able to employ the half-inch binocularly with perfect ease, by night or day.
On the Sexual Reproduction of the Infusoria
Authors: Eberhard Ernst
Published: April 2021

After a delay which must have appeared of long duration to all who are interested in the study of the INFUSORIA, the second volume of F. Stein’s excellent work* has made its welcome appearance. The volume contains a general review of the present state of our knowledge respecting the Infusoria ; and especially discusses the difficult problems that have arisen concerning their sexual reproduction, connected with which is the question of the value of the systematic arrangement of the Infusoria, as proposed by Stein himself, to be based upon the mode of disposition of the cilia. This part is followed by a detailed exposition of the systematic arrangement of the heterotrichous Infusoria, in which will be found a full account of Bursaria truncatella, one of the giants of a pigmy world, and whose structure and organization is, for the first time, fully expounded.
The Formation and Structure of a special Waterabsorbing Area in the Membranes covering the Grasshopper Egg
Authors: Slifer Eleanor H.
Published: April 2021

Needham (p. 1272, 1931) divides all eggs into three classes: (a) those which, when first laid, contain too little inorganic matter and water for their complete development and which, consequently, must take in these substances, as well as oxygen, from the medium surrounding them; (b) those which are dependent upon their environment for additional water and oxygen; and (c) those which need only oxygen. Many insect eggs, available data indicate, belong to the second group, and during their development require, besides oxygen, a supply of water greater than that with which they are furnished at the time when they are laid.
The Vitellogenesis of Gasterosteus aculeatus (the stickleback) investigated by the Ultra-centrifuge
Authors: Singh B. N. , Boyle W.
Published: April 2021

1. In the young oocytes the Golgi apparatus has the form of a solid body situated at one side of the nucleus. This body fragments and the pieces spread around the nucleus where they elongate and join up to form a network. This network moves out to the periphery of the cell where it fragments into pieces. No chromophobe part could be seen at any stage.

2. The mitochondria are seen in the earliest stages in the archoplasmic area. Here they occur as a number of scattered granules. In the later stages they are seen distributed in clumps throughout the cytoplasm.

3. Pat arises in the area which has been vacated by the juxtanuclear Golgi apparatus (archoplasmic area). Prom here it spreads around the nucleus and out through the cytoplasm. There is no connexion between the Golgi apparatus and the secretion of fat.

4. The passage of material from the nucleoli through the nuclear membrane as fine granules has been described. These granules pass to the periphery of the egg where they swell up, become surrounded by a vacuole, and give rise to yolk.

Only the nucleolar extrusions and the yolk stained with neutral red.

5. After centrifuging, the contents of the egg become separated into five distinct layers as follows, beginning at the centripetal pole: fat, cytoplasm, Golgi material, yolk, and nuclear material with mitochondria.
On the Antennal Musculature in Insects and other Arthropods
Authors: Imms A. D.
Published: April 2021

The first antennae of arthropods are divisible into two main types, viz. (1) segmented antennae and (2) annulated antennae. In the first type the antenna consists of a variable number of segments, each having intrinsic musculature. The antennae of the Chilopoda, Diplopoda, Pauropoda, Symphyla, Collembola, and Thysanura Entognatha all pertain to this type; also, the first antennae of many Copepoda and Ostracoda.

In the second type the antenna consists of a peduncle or protopodite composed of one or more segments, each with intrinsic musculature. Distally it bears an annulated flagellum, or a pair of flagella, devoid of intrinsic muscles and whose movements are effected by muscles originating within the peduncle. The first antennae of the Crustacea Malacostraca and the antennae of the Thysanura Ectognatha and of all the Insecta Pterygota belong to this type.

The greatly elongated antennae of the Schizotarsia are intermediate between these two types. They are composed of an immense number of small annuli and an elaborate intrinsic musculature is present, thus allowing these appendages a wide range and flexibility of movement.

The absence of intrinsic muscles in the antennal flagellum throughout the Insecta Pterygota and the Malacostraca appears to be irreversible in the sense that such muscles are never reacquired. It thus lends support to the generalization known as Dollo’s Law.

The presence of segmented antennae in the Thysanura Entognatha affords additional evidence in support of the Symphylan theory of the ancestry of insects.
Spolia Bermudiana. I. On a remarkable new type of Auricularia larva (A. bermudensis, n.sp.)
Authors: Garstang Walter
Published: April 2021

During a visit to the Biological Station at Bermuda in February 1935, I collected many specimens of Chun’s large, highly frilled Auricularia nudibranchiata, originally discovered off the Canary Islands, and in addition found several smaller Auriculariae with arms and bands of simpler type, yet of more than usual complexity. Thinking that these larvae might possibly be the unknown early stages of Chun’s species, I postponed their description in the hope of eventually securing intermediate stages which would establish the relationship. On my second visit in June-July 1938 A. nudibranchiata was scarce, but one small, frilled Auricularia turned up which hade fair to fill the gap. On my return to England I carefully compared the new specimen with its predecessors, and found to my surprise that, while approaching A. nudibranchiata in the ‘arabesque’ folding of its ciliated bands, and fitting the smaller specimens as a further stage in their development, it was itself at the climax of development, and presented clear and specific differences from A. nudibranchiata. Moreover, the life-history of the new species, thus pieced together, exhibits certain anatomical features and changes of exceptional interest. The present paper is devoted to a description of this new type, based on the four specimens secured, its comparison with A. nudibranchiata, and some general observations arising out of its examination.
The Myenteric Nerve-Plexus in some lower Chordates
Authors: Kirtisinghe P.
Published: April 2021

The arrangement of the myenteric nerve-plexus is simpler in fish, much simpler in Amphioxus, than in the higher forms. The nerve-cells in it are not grouped into distinct ganglia at the points of crossing of the fibre-bundles. In Scylliorhinus only two or three cells are present at such points, while in Teleosts the nerve-cells are situated in the meshes of the plexus, as is also the condition in Amphioxus.

In Scylliorhinus these nerve-cells are all of Dogiel’s type II; in Teleosts they belong to both types I and II. In Amphioxus bipolar nerve-cells are definitely present in addition to the stellate ganglion cells described by Boeke.

Synapses between (a) the pre-ganglionic fibres and the enteric neurons, and (b) the enteric neurons themselves are figured and described.

The ‘interstitial cells’ of Cajal are present in the muscle-wall of the gut of fish. A connexion between this system and the enteric plexuses is not to be observed.

The enteric plexuses of fish and Amphioxus are not in the form of a nerve-net. It is not possible to compare the enteric plexus of Amphioxus with the system of ‘interstitial cells’ of the higher chordates. The stellate ganglion cells of Amphioxus are to be compared with the neurons of type I in the higher forms.