bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Reproductive Processes of Earthworms: Part I. The Process of Copulation and Exchange of Sperms in Eutyphoeus waltoni Mich
Authors: Bahl Karm Narayan
Published: April 2021

The method of exchange of the seminal fluid in Eutyp hoe us is very simple and direct as compared with the elaborate process in Lumbricus. No intermediate structures like the clitellum and temporary seminal grooves take part in the process in Eutyphoeus. During sexual congress, the co-operating worms become attached to one another in a head-to-tail position in such a way that the spermathecal apertures (7 /8) of one are apposed to the penial segment (seventeenth) of the other and vice versa. The male ‘genital pits’ are everted to form ‘genital cups’ and the penis is protruded. The genital cups produce a suction on the area of skin surrounding the spermathecal pores of the co-operating worm, and thus cause the formation of spermathecal papillae. In this way a ‘peg and socket’ joint is formed at four places in a copulating pair and, at each joint, the attachment is intimate, the genital cup closely embracing the spermathecal papilla and the penis penetrating the spermathecal duct. There is a further attachment between the ventral surfaces of the two worms by means of permanent copulating papillae and temporary integumentary outgrowths. The function of the penis as an intromittent organ in Eutyphoeus has been elucidated for the first time and a distinction has been made between ‘functional’ and ‘reserve’ penial setae. The exchange of sperms is mutual. The penes inject both spermatic and prostatic fluids into the spermathecae. The sperms are invariably found in the diverticula and n o t in the ampulla, which probably contains a secretion of its own epithelium. There is some evidence to believe that the prostatic fluid serves a nutrient medium for the sperms in the seminal chambers of the diverticula.
Memoirs: The Muscles of the Adult Honey-bee (Apis mellifera L.)
Authors: MORISON GUY D.
Published: April 2021

1. The entire musculature of the alimentary canal is described in gross and in histological detail. The development of the muscle is considered. The innervation is described, likewise the tracheation and its relation to muscular activity and the bloodstream.

2. The heart is described with a detailed histological account of its muscle-fibres. Its tracheation is described and its apparent lack of innervation is discussed.

3. The ‘alary’ muscles of the dorsal diaphragm are described with a detailed account of their histology, innervation, and tracheation.

4. The ventral diaphragm is described as well as the histology, innervation, and tracheation of its muscle-fibres. The course of blood and physiological questions connected with it receive discussion.

5. The muscles of the reproductive organs of drone, queen, and worker are described with particular reference to the histology, innervation, tracheation, and physiology of their fibres.

6. The indirect muscles of the wings (fibrous muscle) have their histology, innervation, and tracheation described in detail. The method of contraction of the entire muscles and of the individual fibres and fibrils is discussed. The sarcosomes are described with their physiological significance to contraction.

7. The attachment of all the types of muscle found in the bee is described in histological detail. Different opinions of muscle attachment to chitin are summarized.

8. Throughout the paper, histological measurements are given for the various types of muscle-fibres and their nuclei in the three castes of bee. Since in the three castes the histological appearance is so similar for each type of muscle, the illustrations have been limited to portions of the muscles of worker bees.
On the Development of Botrylloides
Authors: Garstang Sylvia L. , Garstang Walter
Published: April 2021

The development of Botrylloides adds a new feature to the already complicated structure of the neural canal in T u n i c a t a. The anterior pre-sensory region of the canal was already known in Ciona, Clavelina, and Distap 1 ia to become converted into part of the so-called hypophysial duct, which terminates in front in the ciliated funnel and gives rise to the subneural gland and adult brain. Here, in Botrylloides, the same pre-sensory region is much more pronounced and becomes longitudinally differentiated into two parts, lying one above the other—a large ventral precerebral lobe, which disappears entirely before the tadpole stage is reached, and a slender dorsal precerebral duct, which persists, and is comparable in all essential respects with the hypophysial duct of other Ascidians. The duct in Botryllids communicates with the oral region of the pharynx by a ciliated funnel and gives rise to the brain by proliferation from its ventral wall behind. It fails to produce a special neural gland, but as its own walls assume a glandular character in the adult stage, the difference in this respect is insignificant. Its position above the adult brain is shared with most Stolidobranchiate Ascidians, and in these the neural gland, when present, is developed above the brain, instead of beneath it. The one Botryllid feature which demands special explanation, therefore, is the peculiar development and fate of the large, transitory precerebral lobe in front of the cerebral vesicle.
Experimental Studies on the Histology of the Mammalian Thymus
Authors: Deanesly Ruth
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
A modified Gold Chloride method for the demonstration of Nerve Endings
Authors: Gairns Fred W.
Published: April 2021

During a series of histological investigations into the nervesupply of certain skeletal muscles, which have from time to time been undertaken in this laboratory, great difficulty has been found in obtaining constant and satisfactory results.
The development of the Club-shaped Gland in Amphioxus
Authors: Goodrich Edwin S.
Published: April 2021

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

Hatching 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

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

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.
The Biological Relationship between Septobasidium retiforme (B. & C.) Pat. and Aspidiotus Osborni New. and Ckll
Authors: Couch John N.
Published: April 2021

S. retiforme (B. and C.) Pat. is associated with A. Osborni New. and Ckll. The fungus insect relationship is perennial, depending only upon the life of the tree. The fungus furnishes a home and protection for the scale insects. The scale insects suck the juices of the host plant, grow, and finally reproduce their young in vast numbers. These young may pursue one of three courses: (1) they may settle down beneath the same fungus under which they were born and repeat the cycle; or (2) they may crawl out to other fungus-insect colonies; or (3) they may crawl out and settle down on the clean bark. The latter insects are entirely responsible for the dissemination of the fungus. Certain young become infected soon after they are born. The manner of infection; the development of the fungus within the bodies of the young; and the final growth and establishment of new fungus-insect colonies are described. Parasitized insects are proportionately much more abundant during the late spring and summer months than during the fall and winter months. The type of parasitism is of a highly specialized nature. The fungus enters the circulatory system of the living insects and there develops numerous coils which absorb food from the insect. A number of the insects are finally killed and used up by the fungus; others, though infected, may digest the fungal haustoria and survive to reproduce, and some are free from any infection. Such a conjoint relationship beneficial both to the fungus and to the scale insects is obviously symbiotic.
A New Protozoon, Hyperidion thalassemae n. gen., n. sp., from the intestine of Thalassema neptuni Gärtner
Authors: Mackinnon D. L. , Ray H. N.
Published: April 2021

In the spring of 1930 we found in the intestine of the echiurid worm Thalassema neptuni at Plymouth a peculiar protozoan organism which seems worthy of some description. During the summer term we had additional specimens of the worm sent to us from Plymouth and kept them under observation in the laboratory, but we learnt little more about the parasite than we had already gathered from our earlier observations. We examined, in all, 145 worms: 20 per cent, of those dredged in the sound were infected, but we never found the parasite in those taken between tide-marks.
The Development of the Skull of Scyllium (Scyliorhinus) canícula L
Authors: Beer G. R. de
Published: April 2021

The development of the skull of Scyllium canicula has been studied from the first appearance of cartilage, through thirteen stages, up to the point at which the main features of the adult skull have been acquired. The parachordals are the first elements to chondrify, and evidence is presented confirming Goodrich’s observations con- cerning the visible traces of metameric segmentation of the metotic region of the parachordal. The auditory capsule chondrifies from the first in con- tinuity with the parachordal, to which it is attached by the anterior basicapsular commissure. The polar cartilages have not been found separate, but they appear as nodules of cartilage attached to the under surface of the anterior ends of the parachordals. The orbital cartilage becomes attached to the parachordal by means of the pila antotica, and to the trabecula at the base of the lamina orbitonasalis by means of the preoptic root. The hind wall of the pituitary fossa is formed in a complex manner, from a postpituitary commissure between the polar cartilages, and a pair of inwardly directed processes from the foremost ends of the parachordals forming the dorsum sellae. There is also a precarotid commissure, enclosing the carotid arteries in a foramen between itself and the postpituitary commissure. The basicranial fenestra has been demonstrated. Arguments are given for rejecting Allis’s view that the so-called basicranial fenestrae throughout the craniates are not homologous. Attention is called to the vacuity in the median wall of the auditory capsule through which the posterior canal bulges, and to the fact that this vacuity is not to be confused with the fora- men endolymphaticum. The relations of the glossopharyngeal nerve are described, and it is shown that its apparent passage through the cavity of the auditory capsule is to be ascribed to the fact that the lamina hypotica of the parachordal acts as a false floor to the auditory capsule, the true floor of which is in this region un- chondrified. The problem of the relations of the jaws to the brain-case is reviewed in the light of recent investigations, and a reasoned classification is attempted. It is noticed that chondrification is delayed in embryonic material collected from Naples, as compared with material of similar size and degree of development obtained from Plymouth.
The Activities of the Tube Feet of Asterias rubens L.: I. The Mechanics of Movement and of Posture
Authors: Smith J. E.
Published: April 2021

1. An account is given of the muscular anatomy of the foot and ampulla of Asterias rubens. An intrinsic musculature of the sucker figured by Cuénot (1891) and Chadwick (1923) is shown not to be present; on the other hand, postural muscles responsible for orientating the podium, levator fibres which ‘cup’ the sucker, and radial fibres which flatten it are described and figured for the first time.

2. The role of the different muscle systems, the collagen connective tissue, and the fluid of the hydrocoel in protracting and retracting the foot, and in effecting the attachment and detachment of the sucker, is discussed.

3. Evidence is presented, to show that postural pointing of the foot is brought about by the contraction of a ring of muscles encircling the base of the podium. The orienting muscles are functionally, but not anatomically, distinct from the longitudinal fibres of the retractor sheath.

4. The ambulatory step is shown to comprise a series of linked phases of static posture and of movement. Each phase is characterized by the contraction of one member of each of the two opposing pairs of muscles engaged in the development of the step. The two pairs of muscles are (1) the anterior and posterior orienting fibres, and (2) the protractors and retractors of the foot. In its ideal form the step comprises four phases of static posture alternating with four movements. Each movement is ushered in by a reversal of the contraction-relaxation relationships of one of the two pairs of opposing muscle systems. Four such changes are possible and they occur in a sequence that ensures the orderly succession of the four movements of protraction, swing back, retraction, and swing forward, of which movements the idealized stepping cycle is composed.

5. The actual locomotory step departs from the ideal form in two respects: (1) it is liable to become disrupted by a delay in the initiation of the protraction or of the backswing movement, and (2) withdrawal of the podium occurs simultaneously with its re-orientation in the forward direction. It is pointed out that these variations are explicable on the assumption that, in the two series of opposing muscle pairs, the retractor fibres are more readily excited to contract than are their antagonists, and the anterior postural muscles than the posterior postural fibres.
The Nephridia of Geonemertes dendyi
Authors: Pantin C. F. A.
Published: April 2021

Geonemertes Dendyi (Dakin) is a terrestrial nemertine. The genus has a predominantly Australian distribution, but in recent years this species has been recorded from the western parts of England and Wales (Waterston and Quick, 1937; Pantin, 1944). In this genus the nephridial system is highly developed, and its structure in several species has been described by Hett (1924), Coe (1929), and others. Stammer (1934) mentioned the existence of a nephridial system in G. dendyi but did not describe it. The present work arose from a study of this species collected in South Devon, in all stages from the newly hatched young to the adult. The nephridial system proves to be at least as highly developed in this as in other species, and there are points of some interest regarding its function.
The Behaviour of Mammalian Skin Epithelium under Strictly Anaerobic Conditions
Authors: Medawar P. B.
Published: April 2021

In the course of some experiments on the nature of skin transplantation immunity, it became necessary to find out for how long (if at all) mammalian skin epithelium can survive in the total absence of atmospheric oxygen. The results of the investigation are summarized here in the hope that they may be useful to other students of tissue behaviour.
Further Observations on the Glomerular Root of the Vertebrate Kidney
Authors: McManus J. F. A.
Published: April 2021

There is a gap in the reticulin at the glomerular root of the mammalian kidney. This gap leaves the macular segment of the second convoluted tubule in intimate contact with the arteriolar cells, which in this region contain granules consisting of or containing masked lipoid. Methods are given for the demonstration of these granules in the mouse, rabbit, and man.

The cells of the macula densa of the mouse are poor in lipoid, and there is thus a striking contrast both with the adjoining cells of the same tubule and with the adjacent arteriolar cells.
The Golgi Material of the Neurones of the Central Nervous System of Sheep Infected with Louping-ill
Authors: Gresson R. A. R. , Zlotnik I.
Published: April 2021

1. The Golgi material of the pyramidal cells of the cerebral cortex, the Purkinje cells of the cerebellum, and the multipolar cells of the medulla oblongata and ventral horns of the spinal cord of the sheep is present as filaments and as irregularly shaped bodies. In some of the cells, particularly in the lamb (Sheep V), the Golgi material has the appearance of a network. As it is frequently present as separate bodies it is suggested that it may always consist of discrete Golgi elements which are sometimes situated in close proximity or in contact with one another. Filamentous Golgi elements are present in the basal part of the cell processes.

2. An examination of neurones from the corresponding regions of the central nervous system of sheep infected experimentally with louping-ill showed that the Golgi material undergoes changes consequent upon the invasion of the cells by the virus. The Golgi material undergoes hypertrophy, and at the same time there is a reduction in the number of filamentous Golgi elements and a reduction in the amount of Golgi substance present in the cell processes. These changes are followed by fragmentation. All the neurones of a particular region are not affected equally at the same time. The Golgi material of the Purkinje cells tends to form groups in the cytoplasm prior to fragmentation. In the multipolar cells of the medulla oblongata the hypertrophy of the Golgi material is not as great as in the other regions of the central nervous system. The Golgi material of the motor nerve-cells of the ventral horns of the spinal cord undergoes considerable hypertrophy which is followed by a grouping of the Golgi elements and fragmentation.
Amoeba kerrii (n. sp.): Morphology, Cytology, and Life-History
Authors: Taylor Monica
Published: April 2021

1. An amoeba characteristically blackish when viewed under the low power of a Greenough binocular in reflected light was discovered and isolated from macerating water weeds found in fresh-water pools on the shore near the Marine Biological Station of Keppel.

2. A study of its morphology revealed its relationship to Schaeffer’s genus Metachaos. For reasons given above, the name Amoeba has been retained for the genus and the specific name kerrii has been given in honour of Sir John Graham Kerr.

3. The life-history has been worked out by means of pure-line cultures.

4. The cyst measures about 9µ in diameter. The newly hatched amoebulae grow slowly and develop eventually into young adults which, because of the small size of their crystals and nutritive spheres, are much less dusky than the mature individuals first discovered. An average adult size in creeping is 504 by 576µ.

5. The nucleus, which divides by mitosis, has the same general build as that of A. discoides, A. proteus Y, A. lescherae. Immediately under the nuclear membrane is an achromatic network containing chromatin blocks and connected with a more or less centrally placed karyosome, the whole immersed in-nuclear sap. The nucleus assumes varying shapes as it is rolled about by the streaming endoplasm.

6. Morula-like spheres (= the fission-spheres) give rise to two daughter amoebae by cleavage along a meridional central plane. Fission is confined to young adults.

7. A fission cycle is succeeded by a reproductive cycle. Any mature amoeba can give rise to encysted young which are formed by the action of chromidia escaping from the nucleus. The cyst-wall is single. Hundreds of encysted amoebulae may be formed from one mature amoeba. No sexual stages occur.
The Developmental Cycle of Botrylloides
Authors: Berrill N. J.
Published: April 2021

Of the many studies made on ascidians in the past, few have included the organism in its entirety. The present account is of the whole developmental cycle of an organism exhibiting exquisite timing in its four-dimensional relationships, with an interpretation of a colonial organism as the result of a few interacting processes. A comparison of Botrylloides with Botryllus affords some analysis of the nature of differences of generic magnitude, as modifications of several basic activities.
Some Observations upon the Golgi Elements of the Anterior Pituitary Cells of Normal and Stilboestrol-treated Male Rats, using the Sudan Black Technique
Authors: Foster C. L.
Published: April 2021

It was found possible to demonstrate the Golgi zones of the cells of the anterior pituitary (pars distalis) of the rat with Sudan black. The position and general morphology of the Golgi bodies closely resembled that revealed by the standard osmium tetroxide techniques. The Golgi zone was generally found to contain three sorts of element: (?) diffuse sudanophil material in which were embedded: (b) clear vacuoles and (c) strongly sudanophil bodies. The latter were often associated with the surfaces of the vacuoles, when they were in the form of (1) crescentic caps, (2) partial or complete rims of apparently uniform thickness, or (3) small granules. Sometimes the strongly sudanophil bodies were granular and unassociated with vacuoles; there were also vacuoles with no demonstrable lipoid material in association with their surfaces. The effect of stilboestrol was to cause hypertrophy of the Golgi zones and this was associated with (a) an increase in volume of the region of diffuse lipoids, (b) an increase in vacuolation, and (c) a rather more variable increase in the amount of strongly sudanophil material. These changes would appear to indicate a state of heightened secretory activity. The strong affinity of the Golgi area for sudan black suggests that it consists, at any rate in part, of lipoids.
A Comparative Histological Study of Haemosiderin in the Uteri of Mice of Cancerous and Non-cancerous Strains
Authors: Jones Vera E.
Published: April 2021

In mice, haemosiderin is formed in the wall of the uterus from the blood extravasated into the tissues when the placenta breaks away at parturition. The pigment is formed, probably exclusively, within the phagocytes, and forms a mass in the mesenteric wall of the uterus. In mice of the cancerous strain used in this study (R III strain of Dobrovolskaia-Lavadskaia) the haemosiderin is formed more slowly and is disposed of much more slowly than in the non-cancerous strains examined. Phagocytic inefficiency in the cancerous strain is suggested and its possible connexion with susceptibility to cancer is discussed.
Some Applications of Phase-contrast Microscopy
Authors: Barer Robert
Published: April 2021

Some extensions of the simple theory of phase-contrast microscopy are considered. It is emphasized that transparency, rather than thickness, is the limiting factor for the successful employment of the method. Certain transparent insect larvae (Chaoborus, Chironomus) can be observed in the living state by phase-contrast illumination.

The statement that the method is of no value for the examination of fixed and stained sections is based on consideration of an ideal physical case. In practice the method may be a valuable adjunct to routine examination of such material. Examples are given of the application of phase-contrast microscopy to normal and pathological stained sections.
A New Method for Oblique Microscopical Illumination
Authors: Baker John R.
Published: April 2021

The purpose of the technique described in this paper is to provide the easiest possible means of controlling the direction and degree of obliquity of the light used to illuminate microscopical objects.
A Simple Method for Phase-Contrast Microscopy
Authors: Kempson D. A. , Thomas O. L. , Baker John R.
Published: April 2021

The method described in this paper enables anyone to use phasecontrast microscopy without waiting to obtain special objectives or condensers.
Nervous Structure of the Spinal Cord of the Young Larval Brook-Lamprey
Authors: Whiting H. P.
Published: April 2021

It is intended to describe here the spinal cord of recently hatched ammocoetes of Lampetra planeri (Bloch). Particular attention will be given to those neurons which may be involved in the somatic sensori-motor arc. It is hoped to base upon this description a subsequent account of the embryo and young ammocoete, which will deal with the successive stages of nervous structure and their relation to the successive patterns of behaviour.
Phosphatase Activity of Drosophila Salivary Glands
Authors: Doyle W. L.
Published: April 2021

The presence of alkaline phosphatase in chromosomes has been demonstrated by means of histochemical staining methods (Danielli, 1946; Krugelis, 1942, 1946). These studies indicated the effects of various fixatives and substrates on the subsequent staining reactions. The present study presents certain quantitative aspects of the effects of acetone, alcohol, and pH on the phosphatase activity of whole salivary glands of Drosophila.
A Further Note on Nile Blue
Authors: Cain A. J.
Published: April 2021

In a previous paper (Cain, 1947) it was shown that nile blue can be used to distinguish between acidic and non-acidic lipoids, and that lecithin stained very deep blue with a 1 per cent, solution, while oleic acid was only faintly coloured. Since lecithin stains, it was suggested that other lipines might stain blue also and that the oleic acid used might be impure.