bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Studies on the Histology of the Mammalian Thymus
Authors: Deanesly Ruth 
Published: April 2021

ABSTRACT
A number of male mice 4-6 weeks old were subjected to irradiation and killed at intervals of 2 hours to 12 days after the treatment. A detailed study was made of the resulting histological changes in the thymus. Immediately after irradiation most of the small thymus cells comprising the cortex of the organ degenerate. Simultaneously the existing connectivetissue elements in the thymus proliferate amitotically, and fresh connective tissue and blood-vessels invade the periphery of the organ from its sheath. Numerous ciliated cysts develop in the thymus, derived from the blood-vessels and their adjacent connective tissue; the majority of these disappear 28 hours after irradiation when resorption of the cell debris is complete. Regeneration is initiated 3 days after irradiation by an enlargement of the nuclei of the thymus cells persisting at the edge of the organ; these, by repeated division, reconstitute the cortex. Fresh medullary areas are formed by the aggregation of the connective tissue and blood-vessels which are carried centripetally during regeneration; most of this tissue degenerates, giving rise to a fresh series of corpuscles of Hassall and cysts. These are transitory structures and have almost all disappeared from the medulla by the time histological regeneration of the thymus is complete, 12 days after irradiation. Small pieces of thymus from an advanced cat embryo were cultivated in normal maternal plasma; the implants were fixed after various periods of incubation, embedded in paraffin and sectioned. The histological changes after incubation are similar to those in the irradiated thymus, before the latter begins to regenerate; they include pycnosis of the small thymus cells and proliferation of fibrous connective tissue. This forms a border round the implant in which fresh corpuscles of Hassall develop, their outer cells being continuous with the fibrous connective tissue. The significance of these results with regard to the normal histology of the thymus is discussed, as are the conclusions of other workers who have studied similar changes in the thymus after experimental involution. Both these experimental studies of the histology of the thymus indicate the complete absence of an epithelial reticulum, such as is frequently postulated; the corpuscles of Hassall, and cysts generally associated with it, are derived from the blood vascular and accompanying connective tissue. A note is added on the reaction of typical lymph nodes to the irradiation; this is slight in comparison with that of the thymus.
Studies in the Origin of Yolk. I. Oogenesis of the Spider, Crossopriza lyoni (Blackwall)
Authors: Nath Vishwa 
Published: April 2021

ABSTRACT
The oogenesis of the spider Crossopriza has been worked out by fresh cover-slip preparations stained with neutral red and Janus green B or kept in 2 per cent, osmic acid from ten minutes to half an hour. Routine laboratory methods have also been used. Treatment with 2 per cent, osmic acid for the period mentioned above does not introduce any artifacts. In the youngest oocyte the Golgi elements are in the form of vacuoles containing a watery and non-fatty fluid, and are embedded in the mitochondrial mass. The solid granular Golgi elements are artifacts produced by the excessive precipitation of metallic silver or osmium inside the vacuoles. The crescent-shaped Golgi elements are also artifacts produced possibly by the incomplete blackening of vacuoles. More probably, however, the crescents are the optical sections of the vacuoles. A process of growth and deposition of fat not miscible with the general cytoplasm inside the Golgi vacuoles gives rise to the fatty yolk-vacuoles. The mitochondria are granular and form a horse-shoeshaped cap on one side of the nucleus of the youngest oocyte. The cap gradually grows into a complete circum-nuclear ring. The ring breaks up, and ultimately the mitochondria are distributed uniformly throughout the cytoplasm. There are no nucleolar extrusions. The albuminous yolk arises independently in the cytoplasm. Experiments with the centrifuge have been performed. The earlier literature on the origin of fatty yolk has been reviewed. There is no structure in the egg of Crossopriza comparable to the ‘yolk-nucleus’ of the spider Tegenaria described by earlier writers.
Reactions of Gammarus to Injury and Disease, with notes on some Microsporidial and Fungoid Diseases
Authors: Goodrich Helen Pixell 
Published: April 2021

ABSTRACT
Since May 1923 numerous specimens of the fresh-water amphipod Gammarus pulex L., from various parts of England, have been kept in my laboratory, and I have made observations on some of the many diseases to which this species is subject. The investigation was started owing to an epidemic of microsporidiosis occurring in Gammarus brought to the Department from Liverpool by Mr. C. S. Elton.1 He and others were using these animals for ecological and genetical experiments, and the disastrous loss of offspring from disease was stopped when the nature of the epidemic was recognized. The infecting organism was Thelohania mulleri, the lifehistory of which is to a great extent known (Stempell, 1902; Léger and Hesse, 1917). There are certain points, however, that still require careful investigation, especially with regard to the propagation of the disease. The following incidents, which came under my observation, throw a little light on this problem. In October 1924 there was a second small outbreak of this same microsporidial disease among some Gammar us chevreuxi, Sexton, which had been bred in the department for three or four generations at least. I am indebted to Mr. E. B. Eord for drawing my attention to this outbreak among his specimens and for handing over to me any that succumbed to it. In two of these the disease had reached the spore stage, and could therefore be definitely recognized as due to Thelohania: one of these specimens had been hatched 21 weeks, the other only 16 weeks. The Gammarus chevreuxi were attaining sexual maturity at that season in from 6 to 7 weeks.
A species of Proboscidiella from Kalotermes (Cryptotermes) dudleyi Banks, a termite of Central America, with remarks on the oxymonad flagellates
Authors: Kirby Harold 
Published: April 2021

ABSTRACT
An interesting group of Protozoa living in termites is that comprising the oxymonads, which in many ways are very different from other known flagellates. By prolongations of the anterior ends of the bodies they may attach themselves to the lining of the intestine, but they are also able to swim about in the lumen of the canal. Having no cytostomes they ingest wood, as do many termite flagellates, through the general surface of the body.
Studies on the Origin of Yolk: II. Oogenesis of the Scolopendra, Otostigmus Feae (Pocock)
Authors: Nath Vishwa , Husain Mian Tasdique 
Published: April 2021

ABSTRACT
In a previous paper (1924) on the egg of the centipede, Lithobius forficatus, one of us (V. N.) described two kinds of yolk, albuminous and fatty. The albuminous yolk is preceded by nucleolar extrusions of a remarkable type, and its origin seems to be associated with them, although no evidence could be adduced that they are directly transformed into the yolk. It was further shown that the juxta-nuclear Golgi apparatus fragments into small granules and small crescentshaped Golgi elements. The former grow in size and give rise to the fatty yolk. Miss S. D. King (1924) confirms the above account of the association of the albuminous yolk with the nucleolar extrusions, but in her opinion this type of yolk arises directly from these extrusions. With regard to the Golgi apparatus she admits that it fragments into small granules. Furthermore she describes fatty yolk :—’ the origin of this fatty yolk is doubtful, but it may possibly be connected with the Golgi apparatus, although no evidence in support of this theory has been discovered ‘. In our opinion Miss King is doubtful of the origin of fatty yolk from the Golgi apparatus, because ‘both Mann-Kopsch and Da Fano material was studied, but the latter gave such favourable results that it was used almost exclusively ‘(spaced words ours). Now it is well known that the Da Fano method fails to show fat in the finished slides, while the Golgi apparatus is preserved. On the other hand the Mann-Kopsch method preserves both Golgi apparatus and fat, and thus enables one to study the transformation of the former into the latter. Furthermore, Flem-ming-without-acetic, which Miss King has used, shows fat, but not the Golgi apparatus, at least in the egg ofLithobius. In a later paper (1926), however, Miss King has shown that ‘the formation of fatty yolk from the Golgi elements in O ni sous is strictly comparable to the process described by Nath in Lithobius… .’
The Muscles of the Adult Honey-Bee (Apis mellifera L.)
Authors: Morison Guy D. 
Published: April 2021

ABSTRACT
The chemistry of the muscles is described in outline. With it are included pH values and pigment. The appearance of muscle under polarized light is discussed. The effects of age and fatigue on muscle could not be determined by the techniques adopted. The theories of muscular contraction are summarized briefly.
Physophaga sappheira, n.g., n.sp
Authors: Percy Muriel 
Published: April 2021

ABSTRACT
If Gammarus pulex can be caught in the act of moulting, the cast-off chitinous exoskeleton will often be found to contain a crowd of minute ciliates that dart to and fro with extraordinary rapidity. At this stage they are quite transparent and colourless, but in the course of a few minutes they begin to swell and turn faintly blue, and their movements become less violent. They remain for some hours in the moult, passing ceaselessly up and down inside the appendages and about the proctodaeum, increasing to three or four times their original size and often deepening in colour to a rich sapphire blue.
The Conus Arteriosus in Fishes
Authors: Parsons C. W. 
Published: April 2021

ABSTRACT
The term ‘conus arteriosus’ is used to define the whole of the headward portion of the heart in fishes which intervenes between the ventricle and the anterior boundary of the pericardiac space. A brief description of the conus arteriosus in a number of different forms is given and attention is directed particularly (a) to the musculature of the conus wall, (b) to the number of endocardiac ridges or valves which it contains, and (c) to the position of these ridges in relation to the headward boundary of the pericardiac cavity. The latter is taken as a fixed point morphologically and therefore as giving true indications of the positions of the ridges (right, dorsal, left, and ventral). Thus, in Dipnoi, the conspicuous longitudinal ridge or fold which forms the conus septum is morphologically right in position. The hearts examined include those of Acanthias, Raia, Scyllium, and Pristiurus, Polypterus and Lepidosteus, Amia, the Dipnoi, and various Teleostei. Among the latter are Megalops, Gymnarchus, and Symbranchus. The tendency to reduce the contractile function of the conus and to restrict its valves to the ventricular end is noted even within the Elasmobranchii. The process has advanced so far in Teleostei that the entrance to the lumen of the conus is protected by only one pair of valves as a rule, and the conus has lost its myocardiac covering. Megalops is one of a small number of exceptional Teleostei in which the endocardiac valves are more numerous. The number and position of endocardiac valves in Cyclostomata is similar to their number and position in Teleostei. Discussion is confined (1) to the primitive number of endocardiac ridges ; (2) to the evolutionary significance of the conus arteriosus in fishes ; (3) to the function of the conus arteriosus in Teleostei.
Studies in the Origin of Yolk: III. Oogenesis of the Firefly, Luciola gorhami
Authors: Nath Vishwa , Mehta Dev Raj 
Published: April 2021

ABSTRACT
In the first two papers of this series1 one of us has shown, by studying both fixed and fresh preparations stained with vital dyes, that the Golgi elements in the youngest oocytes of the spider and Scolopendra consist of vacuoles which, after treatment with various fixatives, do not show any coagulum inside their interior, indicating that their contents are watery and non-fatty. When the oocyte begins to enlarge, the majority of these vacuoles, by a process of growth and deposition inside their interior of colloids in the form of free fat not miscible with the general cytoplasm, give rise to fatty yolk-vacuoles, which henceforward show a distinct black coagulum inside their interior after treatment with osmic acid. By this process the refractive index of the Golgi vacuoles is considerably raised, and it becomes increasingly easier to study them in fresh preparations. In the case of the firefly, Lucióla gorhami, however, which forms the subject of the present paper, we observed the remarkable thing that the Golgi vacuoles of the female primordial germ-cells contain free fat as proved by their blackening in 2 per cent, osmic acid in ten minutes. When the oocyte is differentiated and begins to enlarge many of these vacuoles grow in size and give rise to fatty yolk-vacuoles. Lucióla, therefore, is a very valuable material for the demonstration of the origin of the fatty yolk-vacuoles from the Golgi vacuoles, inasmuch as the latter are fatty from the very beginning.
Nucleolar Phenomena During Oogenesis In Certain Tenthredinidae
Authors: Gresson R. A. R. 
Published: April 2021

ABSTRACT
1. Oxyphil nucleolar emissions have been found in two Tenthredinid species of two different genera. In origin the emissions are buds from the oxyphil nucleolus, and in T h r i n a x macula also from a large oxyphil body; their fate appears to be extrusion to the ooplasm.
2. Basophil material has also been found in both species, but whereas in T h r i n a x macula it originates by budding from the basophil nucleolus, in Allantus pallipes it is found as spherical bodies residual after the transformation of the early basophil nucleolus into an oxyphil nucleolus. Regarding the fate of these buds and bodies everything points to their being extruded into the ooplasm.
3. These two kinds of nucleolar emissions are elaborated practically simultaneously in Thrinax macula, but in Allantus pallipes their presence together has only been detected, so far, after the original basophil nucleolus has become transformed into an oxyphil one.
4. These observations on oxyphil and basophil nucleolar emissions, produced in the manner described under 3, appear novel in the study of insect oogenesis at least, and their nearest parallel appears to exist in the mollusc Patella.
The Early Prophases of the First Oocyte Division as seen in Life, in Obelia geniculata
Authors: Faulkner G. H. 
Published: April 2021

ABSTRACT
Obelia is a very suitable subject for the observation of living oocytes, for although the eggs attain a comparatively large size, e.g. 0·2 mm., the yolk deposited in them is perfectly colourless and transparent, and allows the whole of the nuclear cycle to be examined in considerable detail; a - inch objective was used in this case, but an even higher power could be used equally well. As the medusa itself is perfectly transparent, the eggs may be examined in situ in the gonads, hence they undergo the minimum amount of handling and interference, and remain healthy during prolonged observations. It is even possible to keep isolated individuals alive and examine the gonads from day to day.1
The Histology of the Alimentary Tract of the Plaice (Pleuronect?s plat?ssa)
Authors: Dawes Ben 
Published: April 2021

ABSTRACT
Structures similar in detail to the taste-buds of mammals occur in the epithelium of the pharynx, which is considered as a distinct region for reasons given. The oesophagus possesses an extremely well-developed musculature composed of striated fibres and an intensely folded mucosa liberally beset with goblet-cells. There are no glands present, and it is sharply defined from the stomach. The musculature of the stomach consists of non-striated fibres, and there is no differentiation between the gastric glands at the ‘cardiac ‘and ‘pyloric ‘ends of the stomach, except that in the former position they are more shallow. Three types of cells enter into the composition of the gastric mucosa, superficial cells forming the surface epithelium and that lining the crypts, mucus-producing cells forming the neck of the tubule, and granular cells forming the basal, secretory portion of the tubule. Parietal or oxyntic cells do not occur, nor do goblet-cells, in any part of the gastric mucosa. The intestinal mucosa is folded so as to simulate crypts and villi, but it is shown that these structures do not occur. There is no differentiation of the intestinal epithelium except into goblet-cells. Leucocytes are seen in all zones of the epitheliumat all times but in relatively small numbers which appear constant, so that they probably do not play any considerable part in food absorption. The pyloric caeca exhibit the same histological structure as the intestine and are in open communication with this part of the alimentary tract. They are probably secretory and absorptive like the duodenum and intestine. A well-developed valve occurs at the junction of the intestine and the rectum. The rectum shows the same structure as the intestine except that the folds are deeper and more considerably beset with goblet-cells and the musculature thicker. Goblet-cells disappear from the mucosa near the anus.
Metamerism in Enteropneusta
Authors: van der Horst C. J. 
Published: April 2021

ABSTRACT
The Chordate affinities of the Enteropneusta were advocated first by Bateson, who even included this group of animals amongst the Chordata. Most subsequent investigators of the Enteropneusta (MacBride, Willey, Ritter, and Heider in particular) supported Bateson’s conception and even tried to give it more evidence. On the other hand, Spengel, the accepted imperator in the knowledge of the group, as Ritter rightly observes, denies all relationship between the Enteropneusta and the Chordata; he believes that Balanoglossus is distantly allied to the Annelida, and that the Tornaria is a modified Trochosphere. If the relations of the Enteropneusta with the Pterobranchia, Phoronis, and Echinoderms be left out of the question, as these can be considered to be mere side-lines in the course of evolution, it becomes apparent that the Enteropneusta, either through their relation to the Annelida or to the Chordata, are allied to segmented animals.
The Cytology and Binary Fission of Peranema
Authors: Brown Virginius E. 
Published: April 2021

ABSTRACT
The Peranemidae are animals of a primitive type and they show rather close phylogenetic relationships to the lower protistan forms. Peranema affords good cytological material. They have a clear cytoplasm and therefore their kinetic elements are easily determined. Likewise they are easy to culture. Thereby they can be obtained in quantities large enough to allow of good cytological investigation. Also the study of their cytology is of interest, for the conception of the Protozoa as a primitive type has led to various studies which may bring to light a better interpretation of the riddles of protozoan morphology.
The development of the Club-shaped Gland in Amphioxus
Authors: Goodrich Edwin S. 
Published: April 2021

ABSTRACT
The club-shaped gland of the larva of Amphioxus has attracted much attention since its development was first studied by Kowalevsky in 1877 (4), who believed it to be derived from the first mesodermal segment. Hatschek, in his classical work published in 1881 (3), corrected this error, and described the origin of the gland from a transverse thickening of the endodermal wall of the gut on the right side opposite the mouth in the region of the first myotome. He states that, in the embryo of about 10 segments, this thickening extends dorsally up the right side, and ventrally on to the left side ; that it becomes folded, a groove being formed on its inner surface ; and that by the closing of the lips of the groove it finally becomes separated off as an elongated sac from the gut (‘Gegen das Ende der embryonalen Période erfolgt der Verschluss der Rinne und die Abschnürung dieser Bildung vom Darme ‘, p. 74). This sac on the right of the gut has a narrower prolongation to the left, which soon acquires an opening to the exterior just below the edge of the mouth (see Text-fig. 1). In the larva, then, the gland, whose wall is now formed of a layer of characteristic large cubical granular cells, opens by means of a duct partly ciliated and lined with flattened cells ; while at an earlier stage it is supposed to be a closed sac (‘der ganzen Lange nach zur Abschnürung gekommen ‘, p. 75).
The Hatching of Insects from the Egg, and the Appearance of Air in the Tracheal System
Authors: Sikes Enid K. , Wigglesworth V. B. 
Published: April 2021

ABSTRACTHatching spines are described in the bugs, Cimex and Rhodnius; and in the lice, Polyplax, Pedicinus, Pediculus, Phthirus, and Haematopinus. In all these insects the spines occur on the embryonic cuticle which is shed at the time of hatching.The mechanism of hatching is described in the following insects: the flea (Ceratophyllus), the mealworm (Tenebrio), the grain moth (Sitotroga), the blow-fly (Lucilia), the bed-bug (Cimex), and the sucking-louse (Polyplax).In the light of these, and other observations in the literature, the general mechanism of the hatching of insect eggs is discussed.The first appearance of air in the tracheae of these insects is described and the mechanism of the process considered. It is suggested that the fluid in the tracheae is absorbed by the osmotic pressure of the tissue-fluids, and that since osmotic pressure is increased by muscular activity, air appears earliest in those insects which show the greatest activity while in the egg. It is argued that osmotic pressure will account also for the appearance of gas in the closed tracheal system.
The Structure of the Clitellum of Alma emini, Mich
Authors: Grove A. J. 
Published: April 2021

ABSTRACT
Through the kindness of Dr. J. Stephenson, I have been able to examine a specimen of Alma emini, Mich, (from Tanganyika), a Glossoscolecid belonging to the sub-family Micro-chaetinae. This worm possesses several remarkable features, particularly, an unusually long clitellum, the investigation of which seemed likely to throw some light upon the relation of the clitellum to the generative apertures in the evolution of the Oligochaeta, tentative suggestions regarding which were put forward by me as a result of the observations upon the reproductive processes of the Lumbricids Lumbricus and Eisenia (Grove, 1927, p. 471).
Notes on Protodrilus
Authors: Goodrich E. S. 
Published: April 2021

ABSTRACT
The following paper contains some observations on Protodrilus flavocapitatus Uljanin, made chiefly on material from Plymouth. Although Professor U. Pierantoni in his beautiful and valuable monograph on the genus Pro.todrilus (10) added much to our knowledge of these interesting little worms, there remain still many points to be elucidated with regard to their nephridia, genital organs, and mode of reproduction. The work was carried out here, in the Marine Biological Laboratory at Plymouth, and in the Stazione Zoologica at Naples. The worms were studied alive; and also in sections, and in whole and teased preparations of preserved material.