bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Tracheal System of Collembola, with special reference to that of Sminthurus viridis, Lubb
Authors: Davies W. Maldwyn
Published: April 2021

No extensive study of the tracheal system of Collembola has previously been made. The general plan of the tracheae has been worked out on Sminthurus viridis; two independent systems exist. The presence of only a single pair of spiracles constitutes a unique condition among adult insects. The position of these is in the anterior region of the prothorax, and not in the head or cervicum as previously believed. The structure of the spiracles is extremely primitive and they possess no closing apparatus. The tracheae branch dichotomously, but no anastomosis exists between the systems of the two sides of the body. Taenidia are present, but no ‘transition cells ‘have been observed and the fine tracheae terminate in unbranched tracheoles. The initial entrance of air into the tracheae is through the spiracles ; the displacement of fluid is very slow and the. whole system is not completely filled with air until about fourteen days after emergence from the egg. Tracheae are found to be a constant feature in all members of the Sminthurinae examined. Various methods of technique adopted are given.
Observations on the Development of the Pronephros of the Sturgeon, Acipenser rubicundus
Authors: Fraser Elizabeth A.
Published: April 2021

The following observations were made from a series of embryos and young larvae of Acipenser rubicundus, which were kindly sent by Mr. W. J. K. Harkness of the Canadian Fisheries to Professor D. M. 8. Watson at this college. I am much indebted to Professor Watson for the loan of this valuable material.
The Origin of Dust-Cells in the Lung
Authors: Carleton H. M.
Published: April 2021

The vital injection experiments of Permar have been repeated. The transformation of endothelial cells of the lung capillaries into dust-cells, as claimed by this author, could not be established on a scale at all sufficient to account for the immense number of dust-cells. The evidence of tissue culture is discussed and is claimed to favour the idea that dust-cells are derived from the cells lining the alveoli, and that these are largely cubical epithelial cells (Binet and Champy; Carleton) and not histiocytes (Lang). That dust-cells are formed from the cubical epithelial cells is urged from the study of sections of dust-laden lungs. That the heart-failure cell has a similar derivation to the dust-cell is also urged. Stages in the formation of dust- and heart-failure cells are described and figured. The changes caused in the pulmonary alveoli by (i) poison gas, (ii) the disease 1 Jagziekte ‘, and (iii) collapse of the lung are discussed. The conclusion is formed that these changes favour the view that the cells lining the alveoli are epithelial rather than histiocytic. Some of the recent work of the Aschoff school (papers of Westhues and Seeman) is described and discussed. Policard’s theory that the final alveolar lining is histiocytic (i. e. mesodermal) is described.

Difficulties for accepting this view are given.
The Development of the Nucleus of Amoeba Proteus. Pallas (Leidy) [= Chaos Diffluens (Schaeffer)]
Authors: Taylor Monica
Published: April 2021

A very thorough knowledge of the nuclear phenomena in an organism so largely employed as is Amoeba proteus by investigators in many branches of science, no less than by teachers of biology, is greatly to be desired. That there are, at present, gaps in this knowledge is quite evident from an inspection of the literature. One such gap was responsible for a question asked of me by Professor Grégoire while I was working in the Carnoy Institute, Louvain, in 1924. This question emphasized the fact that, in my paper on ‘Nuclear Divisions in A. proteus’, I had, as had Doflein (8) before me, left it open whether or no the portions of the karyosome which stain more deeply than the rest consist of chromatin. When reading over the manuscript of my paper Professor Graham Kerr had said that he saw no reason for their not being chromatin, while fully sympathizing with my reluctance to decide the question from observation made on the nucleus of the adult. Griiber (11) had no hesitation in describing these portions of the karyosome as ‘chromatin-containing’? While I was working out the phenomena connected with the formation of encysted young, the karyosome of the fully mature individual had appeared to me to be nothing more than a portion of the nuclear reticulum where the meshes were not quite so large as in the surrounding areas. In contradistinction to this condition was that which obtained in those young A. proteus which I had been able to examine before the publication of my paper (25, p. 137, Text-fig. 10) and of which a preliminary account was given. In these the karyosome appeared much more solid and less reticulate, being quite the most conspicuous structure in the nucleus.
A Contribution to the Embryology of Pieris rapae
Authors: Eastham L.
Published: April 2021

Maturation of the ovum of Pieris rapae takes place immediately after oviposition. Cleavage begins within the first hour, and of the resultant nuclei those destined to form blastoderm move outwards to the cortical layer ; the remainder are left in the yolk as vitellophags. The movement outwards of the nuclei is partly attributed to a streaming of cytoplasm which drags the nuclei to the periphery. The formation of the embryonic rudiment is described, as also are its changes in form, which consist chiefly of an increase in length and decrease in width. These are accompanied by anterior and posterior flexures of the embryo into the yolk. Gastrulation is effected by a process of overgrowth of the middle plate by two lateral plates. This is preceded by differentiation of the middle plate by loss of cells from its whole length to the yolk, and by a shallow invagination developing along the median line of the ventral plate. Endoderm is formed in anterior and posterior rudiments, which develop as proliferations in the positions of future mouth and anus. Yolk-cleavage and amnion and serosa formation are described. All the processes examined in development take place from before backwards.
The Passage of the Spermatozoa into the Cocoon in the Brandling Worm (Eisenia foetida, Sav.)
Authors: Grove A. J.
Published: April 2021

Sections through the albumen of a cocoon fixed some short time after deposition show spermatozoa in varying positions indicative of a condition of inactivity following upon failure to enter an egg. In the albumen of cocoons dissected from off the clitellum of the worm just prior to deposition, no spermatozoa could be detected. In freshly deposited cocoons spermatozoa are to be found surrounding the eggs, but not actually penetrating the vitelline membrane. The outline of the spermatozoa is sinuous, indicating that they were actively swimming at the time of killing.

It is evident, therefore, that although the eggs are passed back into the cocoon whilst the latter is still surrounding the clitellum, the spermatozoa enter during the passage of the cocoon over the apertures of the spermathecae.
Yolk-Absorption in Loligo and the function of the embryonic liver and pancreas
Authors: Portmann Ad. , Bidder Anna M.
Published: April 2021

Although many details of Cephalopod development have long been known to biologists, the physiology of the developing animal was, for many years, practically unstudied. The method by which the yolk is absorbed was, in particular, completely unknown. Faussek, in his paper of 1901, summarized the knowledge then existing, and so few have been the additions of later years that, in the brief abstract now given, we follow him almost verbatim.
The Cytoplasmic Inclusions of Certain Plant Cells
Authors: Patten Ruth , Scott Margaret , Gatenby J. Brontë
Published: April 2021

The plant cell has the following cytoplasmic inclusions : (a) Mitochondria (chondriome). (b) Plastids (plastidome), probably derived from mito chondria. (c) Golgi elements (osmiophilic platelets of Bowen). Plant cells often contain vacuolar spaces filled with a watery fluid. These spaces are sometimes canalicular in arrangement, as shown by Bensley eighteen years ago. There is no evidence that these vacuoles are : (a) Formed from self-perpetuating primordia. (b) Possessed of a lipoid membrane. (c) Associated with the Golgi elements (platelets). There is no reliable evidence that the plant-cell cytoplasm contains any type of protoplasmic inclusion not also found in animal cells, for the plasts are probably enlarged mitochondria, as has been suggested by Mottier, Guilliermond, and others. The so-called ‘vacuome ‘drawn by Bowen (this paper, p. 391) is found almost always in Weigl (Mann-Kopsch) preparations. Such ‘vacuoles ‘and primordia are possibly corro-sive-osmic artefacts caused by the non-ability of water to wash out the corrosive sublimate of the Mann’s fluid, previous to osmication. The osmiophilic platelets are demonstrable by the Kolat-chev and Mann-Kopsch methods, but we have not so far succeeded in showing them with Benda, Flemming-without-acetic, haematoxylin, Champy-haematoxylin, or the silver-nitrate Golgi methods. They resemble closely the dictyosomes of Hemipterous germ cells.
Arcella: A Study in Cell Physiology
Authors: Bles Edward J.
Published: April 2021

The experimental work described in the following paper was carried out, and, in the main, completed during the years 1910—13. But an earnest endeavour to interpret the facts aright, leading gradually to the personal views expressed in the later chapters of the paper, occupied the author’s mind almost up to the day of his untimely death in 1926. His work and thought suffered, however, frequent and long interruptions due to serious illness. Had not his activities been grievously inhibited by that failure of health, further experiments suggested from time to time by his maturing thought about his problem would certainly have been made ; while the results of his work and the conclusions arrived at would have been published long ago.
On the Development of the Skull of Leptodeira hotamboia
Authors: Brock Gwendolen T.
Published: April 2021

Accounts of the development of the Ophidian skull are not numerous. Rathke as early as 1839 described the development in Coluber natrix from a macroscopic point of view. Parker (1878) gave a full description, excellently illustrated, of Tropidonotus natrix, but his work is out of date and it is evident that he was misled in several points, especially over the condition of the orbito-temporal region. He does not appreciate the reduced state of the side-wall in this region, and claims to have identified both an orbito-sphenoid and an alisphenoid. Gaupp makes many valuable contributions to the understanding of the snake skull, but, as he had only a single specimen of a Tropidonotus natrix embryo, he was unable to settle definitely the doubtful points in Parker’s work. Peyer in 1912, with the intention of bringing Parker’s work up to date, gave an excellent account of the stages of development in Vipera aspis, but he failed to settle the problem of the orbito-temporal region satisfactorily. De Beer (1926), in his work on the orbito-temporal region, discussed the problem of the ophidian alisphenoid in the light of the present-day understanding of that bone, but had only one specimen of Tropidonotus and one of Pseudechis at his disposal. He suggested that I should undertake a full investigation of the developmental stages. The work was begun primarily in the hope of reaching a solution to the vexed problem of the ‘alisphenoid ‘. In the course of the investigations several interesting points have come up: the NO. 290 uposterior attachment of the nasal capsule, the probable absence of an extracolumella and the nature of the columella attachment to the quadrate; the homology of the fenestra cochleae.
The Oogenesis of Lumbricus: a Restatement
Authors: Harvey L. A.
Published: April 2021

My former results (1925) have been revised, and the following are now recorded:

The mitochondria are filamentous and granular. They are present in the oogonia as a cap over one pole of the nucleus.

This cap enlarges as the oocyte grows, and finally breaks up and spreads as loose clouds over the entire cytoplasm. Under darkground illumination the mitochondria appear as areas showing a milky scintillation, owing to Brownian movement.

The Golgi bodies are in the form of curved rodlets tapering towards each end and having a patch of sphere material on the concave side. The rodlet only is visible in living cells. Darkground illumination fails to differentiate the Golgi elements from the ground cytoplasm. It is uncertain whether they are derived from one only or more than one Golgi body in the oogonium.

Droplets containing weak fat are present in all older oocytes, and in some ovaries in the younger cells, even being present in oogonia. They arise de novo in the cytoplasm.

The vacuome in this material is a function of the cell’s reactions to neutral red, and is not present in the unstained egg. It arises in close relation to the Golgi apparatus, but in later phases of staining wanders away from it.

Nath’s observations on earthworm eggs, and his theory of the vacuolar nature of the Golgi body, are discussed in detail.
On the Autonomic Nervous System of the Teleostean Fish Uranos copus scaber
Authors: Young John Z.
Published: April 2021

The sympathetic ganglia of Uranoscopus resemble those of mammals in that they are connected with the spinal nerves by white rami consisting of medullated (pre-ganglionic) fibres, and grey rami of non-medullated (post-ganglionic) fibres. The sympathetic ganglia are connected together by a chain in which the medullated fibres may run forwards or backwards and may also cross in transverse commissures to the opposite chain. No sympathetic nerves to the heart were found. The cardiac nerves spring from the vagus and consist of medullated fibres. The gonads and the mesonephros and its derivatives (kidneys, urinary bladder) receive nerves only from the sympathetic system, with the exception of the sphincters round the external openings of the gonads and bladder which are innervated by branches of the spinal nerves. There is, on each side, only a single anterior splanchnic nerve from the sympathetic system to the gut; there is therefore nothing corresponding to the pelvic nerves (sacral parasympathetic outflow) of Tetrapods. The sympathetic chain extends into the head and bears sympathetic ganglia in connexion with the vagus, glossopharyngeus, facialis, and trigeminus nerves. The rami communicantes between these sympathetic ganglia and the cranial nerves consist almost entirely of non-medullated (post-ganglionic) fibres; the pre-ganglionic fibres for these ganglia run out in the white rami of the third and fourth spinal nerves and thence forwards in the sympathetic chain. The ciliary ganglion resembles that of mammals, receiving fibres from the trigeminal sympathetic ganglion (radix sympathica), profundus ganglion (radix sensoria) and oculomotor (radix brevis). The sympathetic fibres in the long and short ciliary nerves (though post-ganglionic) are medullated. There is a bundle of fibres running from the trigeminal sympathetic ganglion via the radix longa and radix brevis to the oculomotor nerve. There is a separate profundus ganglion in Uranoscopus from which a small nerve passes to join the trigeminus (portio ophthalmica profundi?) while larger branches run to the long and short ciliary nerves.
On the Function of the so-called ‘Rectal Glands’ of Insects
Authors: Wigglesworth V. B.
Published: April 2021

It is a characteristic of those animals, such as birds and reptiles, which eliminate their nitrogen in the form of uric acid, that they show an active reabsorption of water from the excrement in the cloaca; so that there is a continuous circulation through the excretory system, enabling the animal to accomplish its excretion with a minimal supply of fluid. In the large bowel of mammals, also, the water secreted in the digestive juices is reabsorbed, and the faeces rendered more or less dry before they leave the body.
The Histochemical Recognition of Certain Guanidine Derivatives
Authors: Baker John R.
Published: April 2021

1. A review of known facts indicates that Sakaguchi’s test gives a positive reaction with all substances having this formula (and with no others):

where α is H or CH3 and β is also H or CH3.

2. Arginine, being a constituent of most proteins, is by far the commonest positively-reacting substance that occurs in the tissues of plants and animals. Galegine and agmatine, which also react positively, are of very restricted occurrence.

3. Details are given of a method whereby Sakaguchi’s test may be applied to paraffin sections.
Ester Wax: A New Embedding Medium
Authors: Steedman H. F.
Published: April 2021

Ester wax is a new ribboning embedding medium. It consists of five substances which may be varied in proportion so that media of different characteristics may be produced. A mixture which will meet most requirements is as follows:

The following facts relate to this mixture:

Melting-point. 46-8° C.

Section range. 2-20 μ at a room temperature of 64° F.

Ribbon range. 2-15 μ at a room temperature of 64° F.

Final compression loss. 7·6 per cent, at 10μ (after flattening).

Solvents. Alcohols, ethers, esters, ketones, hydrocarbons, aldehydes, chlorinated hydrocarbons, natural oils, &c.

Cutting. This must be done more slowly than with paraffin wax.

Flattening. Sections may be flattened on tap-water or aqueous staining solutions. Flattening must be completed in a drying oven at 40-5° C. with sufficient water under the sections to float them.

Staining. Two methods: (1) In the ribbon; (2) As for paraffin wax sections.

Pre-mounting fluid. Xylene, benzene, ligroin, &c.

Mounting fluid. ‘Sira’, or Kirkpatrick and Lendrum’s polystyrene mounting medium.

Conclusion. It is believed that ester wax may open up new methods in histology and cytology. Its greater water tolerance and its property of ribbon staining followed by drying constitute an advantage found in no other embedding medium. Greater use of the wide range of solvents as stain carriers is indicated.
A Quantitative Study of the Osmium Impregnation of the Contractile Vacuole of Chilomonas paramecium (Cryptomonadina)
Authors: Smyth J. D.
Published: April 2021

1. Examination of the contractile vacuole of Chilomonas paramecium during progressive impregnation by the Weigl osmic technique revealed that the so-called ‘osmiophil cortex’ appeared first as a number of perivacuolar osmiophilic granules. Prolonged impregnation caused these to fuse to form a closed ring which, after very prolonged incubation, became a solid osmiophilic mass.

2. Cultures fixed together and osmicated in separate tubes gave more consistent impregnations, in any one series, than those both fixed and osmicated separately.

3. With the two samples of osmium tetroxide used, after normal fixation, A consistently gave impregnations of 62-85 per cent., and C impregnations of 25-36 per cent.

4. Constant mixing during fixation and osmication was not advantageous, and gave more irregular results than normal methods.

5. Time of fixation, between the limits of 5’ to 90 minutes, had no effect on the impregnation.

6. It was suggested that the irregularities of impregnation with a given sample of osmium tetroxide were due to the presence of a trace of some retarding agent, possibly introduced at the time of fixation.

7. It was shown that the osmiophily of the perivacuolar region in Chilomonas did not vary with the vacuolar phase.
On the Structure, Division, and Systematic Position of Trichomonas vaginalis Donné, with a Note on its Methods of Feeding
Authors: Hawes BY R. S.
Published: April 2021

1. Trichomonas vaginalis has been cultivated on various media and a simple method of maintaining cultures on Boeck and Drbohlav’s egg-Ringer-albumen medium is described.

2. The feeding methods of the flagellates in culture have been studied and some evidence of extracellular digestion is recorded.

3. When cultivated on media deficient in carbohydrate, T. vaginalis is reduced to the dimensions of T. hominis, but when adequately fed it maintains its distinctively larger size. Out of forty-eight strains of T. vaginalis, only two developed in culture the long undulating membrane and free posterior flagellum typical of T. hominis in nature.

4. The structure of T. vaginalis has been reinvestigated, (i) It differs constantly and significantly from the intestinal trichomonads of man in size, nuclear organization, and the form of the axostyle and basal fibre, (ii) It also differs from T. hominis in the characters of its parabasal apparatus and cytoplasmic inclusions, and, in nature, in the length of its undulating membrane and in lacking a free posterior flagellum, but for reasons discussed in the text these points are at present considered less reliable in diagnosis than those given under-4 (i).

5. It is concluded that T. vaginalis is a species distinct from all other human trichomonads.

6. The method of division has been described. In general, it follows the same course as T. hominis, but separation of the old, and growth of the new, cytoplasmic structures occurs somewhat later in T. vaginalis, and the old axostyle is retained throughout division. There are five chromosomes, formed during prophase from aggregations of extra-karyosomatic granules.
The Cytology of the Neurones of Helix aspersa
Authors: Thomas Owen Lewis
Published: April 2021

Within recent years the important investigations of Parat (1928), Hirsch (1939), Worley (1943), and Baker (1944) have extended our knowledge of the form, function, and cyclical activity of the intracellular organoids, more especially with regard to the so-called Golgi apparatus.
Further Remarks on the Histochemical Recognition of Lipine
Authors: Baker John R.
Published: April 2021

In an earlier paper (Baker, 1946), a technique was described for the histochemical recognition of lipine. This technique was called the acid-haematein test. It was shown that lipines, after appropriate fixation and subsequent mordanting with potassium dichromate, display a special affinity for hae?atein, with which they react to give a blue, blue-black, or grey colour. If certain precautions are taken, lipines can thus be distinguished from other substances occurring in the tissues of plants and animals. It was found, however, that the crude galactolipine used in the investigation reacted much less strongly than lecithin, cephalin, and sphingomyelin. It will be recollected that galactolipine differs from these other lipines in containing no phosphoric acid radicle. The suggestion was made that if the galactolipine used in the test had been completely free from contamination with sphingomyelin, it might have proved negative to the test. If so, the acid-haematein test would be a test not for lipines in general, but for lipines other than galactolipines; that is to say, it would be a test for phospholipines. It is the purpose of the present paper to report the reaction of purified galactolipine.
The Structure and Deposition of the Cuticle in the Adult Mealworm, Tenebrio molitor L. (Coleoptera)
Authors: Wigglesworth V. B.
Published: April 2021

In three earlier papers (Wigglesworth, 1933, 1945, 1947a) the structure and deposition of the cuticle of Rhodnius prolixus have been described. The main conclusions reached were as follows. The epicuticle is a composite structure made up of four layers: (i) a ‘cuticulin’ layer composed of a condensed lipoprotein subsequently tanned by quinones; (ii) a layer of material rich in dihydroxyphenols; (iii) a thin layer of crystalline, orientated wax molecules responsible for the waterproofing of the cuticle (cf. Beament, 1945); and (iv) an outermost ‘cement’ layer protecting the wax.
An Easily Controlled Method for Staining Mitochondria
Authors: Cain A. J.
Published: April 2021

The great disadvantages of the standard staining methods for mitochondria are that they are very complicated and cannot be applied to different tissues until suitable times for the action of the various stains have been worked out by a long process of trial and error.
Studies on Lagenophrys tattersalli (Ciliata Peritricha, Vorticellinae) Part II. Observations on Bionomics, Conjugation, and Apparent Endomixis
Authors: Willis A. G.
Published: April 2021

A study of the bionomics of L. tattersalli shows that the initial infection of the host is by the passage of swarmers from the gill-plates of the female host to those of the embryo in the brood-pouch. The transmission of the infection from instar to instar is about 50—70 per cent, effective. It is brought about by (i) the mobilization of the entire colony at ecdysis by an obligatory type of division (second-type division), and (ii) by the penetration of the swarmers to the surface of the new instar through splits which appear in the old cuticle as it is shed. The term ‘protoconjugant’ is applied to the organism from which the two microconjugants are formed by binary fission. The protoconjugant is formed by the unequal fission of the parent, and not by budding as in L. platei (Ubisch, 1913). The divisions which produce the proto- and micro-conjugants are compared with the normal asexual reproductive process (first-type division, Willis, 1942). The conjugation process is described. In view of the early fusion of both conjugants, the term ‘synconjugant’ is proposed for the macroconjugant after its fusion with the microconjugant. There are no visible nuclear preparations for conjugation in either conjugant before their attachment. The evidence for a state of ‘Conjugationserwartung’ (Ubisch, 1913) is criticized and shown to be based, in all probability, on specimens produced by the distributive divisions of the synconjugant. The term ‘necrochromidium’ is proposed for the mass of vesicles formed by the degeneration of the macronucleus in conjugation and endomixis. Before the formation of the necrochromidium the macronucleus of the macro-conjugant becomes elaborately branched. The distributive divisions of the synconjugant are described for the first time. Resemblance to other vorticellinids is shown during the intermoult period of the host. At ecdysis, the distribution of the nuclear Anlagen is adapted to the obligatory second-type divisions which are undergone by L. tattersalli at this period. In some cases one of the divisions of the synkaryon is cytoclastic. A process of apparent endomixis is described. In this process unequal fission produces a small organism, resembling a protoconjugant which fails to separate, and a larger organism. The micronucleus of the smaller organism remains undivided and soon degenerates. The micronucleus of the larger organism undergoes two successive divisions to form four nuclear Anlagen. An anomalous process of micronuclear division and reduction is described. One of the micronuclei produced by the division passes into a small bud of protoplasm. Later the latter falls off and degenerates.
The Golgi Material and Mitochondria in the Salivary Glands of the Larva of Drosophila melanogaster
Authors: Hsu W. Siang
Published: April 2021

The salivary glands in the larvae of Drosophila show evidence of serving two functions: (1) production of digestive secretion, (2) accumulation of reserve food for the period of pupation. The two functions proceed simul- taneously within the same cell during certain stages of its development. A single droplet of digestive material has been seen to originate and grow within each Golgi body in the gland-cells. When a certain size is reached the droplet is released into the cytoplasm and by the fusion of two or more of them bigger vacuoles are formed. The secretory material is discharged into the lumen by means of a merocrine mechanism. Neither mitochondria nor nucleus has been observed to take any visible part in the elaboration of secretion droplets. The storage granules found in older and larger cells have been observed to be direct transformations of chondriomites, and neither the Golgi material nor the nucleus shows any sign of participation in the formation of these granules. From the standpoint of morphology and behaviour, the Golgi bodies found in the salivary gland cells are the same as found in the cells of the glandular portion of the proventriculus and the epithelium of the anterior portion of the midgut of the larva. My observations do not lend themselves convincingly to a two-compo- nent conception of the structure of Golgi bodies.
A Simple Method for Orientating Small Objects for Sectioning, with Special Regard to Nematodes
Authors: Overgaard C.
Published: April 2021

For solving certain anatomical problems in free-living nematodes serial sections are necessary. Various methods of orientation proved unsatisfactory for these small objects (in this case 700μ. in length and 30μ in width). The following method was worked out and found excellent:
The Mechanism of Insemination and the Mode of Action of the Spermatophore in Gryllus domesticus
Authors: Khalifa A.
Published: April 2021

The house cricket spermatophore is largely protein and does not contain any chitin. It is composed of an ampulla, a handle, and a long capillary tube terminating in a pointed closure.

The wall of the ampulla comprises four different layers: an outer thin layer, an evacuating fluid, a thick strong inner layer, and a transparent inner membrane. In between the inner layer and the inner membrane, at the top of the cavity, there is the pressure body, a protein mass, divided into two halves. Each half is surrounded by a thin membrane.

The process of emptying a spermatophore is due to osmosis. It has been shown experimentally that the strong inner layer of the ampulla acts as a semi-permeable membrane separating two fluids of different osmotic pressure —the evacuating fluid and the pressure body. When the closure at the tip of the tube is removed, the pressure body swells, exerting a pressure on the sperm as the evacuating fluid passes inwards.
Alkaline Phosphatases and the Cycle of Nucleic Acids in the Gonads of Some Isopod Crustaceans
Authors: Nicola Marina De
Published: April 2021

1. The distribution of alkaline phosphatases and their relation to nucleic acids have been investigated by means of Gomori’s technique in the gonads of Isopod Crustaceans (Asellus aquaticus and some Cymothoids).

2. Alkaline monophosphatases are distributed over the Feulgen-positive structures, in nucleolus, and in_the cytoplasm of young oocytes. They disappear from every place, except nucleoli, during yolk formation. The close coincidence of their localization with that of nucleic acids indicates that they are involved in the metabolism of the latter. The cytoplasmic localization is probably connected with RNA distribution only where this is being actively metabolized.

3. RNA diphosphatases have a similar distribution ; they are present where the acid is present, but they do not follow so closely its cycle. Contrary to monophosphatases, they do not disappear gradually from the cytoplasm of the oocyte, where RNA does so.

4. DNA diphosphatases are partially independent from DNA, because they are present also in some Feulgen-negative structures (cytoplasm and nucleolus). As the RNA diphosphatases, they do not disappear gradually during vitellogenesis.

5. Diphosphatases show also a depolymerizing action on DNA. It seems more likely that this fact is due to a nucleasic action intrinsic in diphosphatases than to an association of these enzymes with a nuclease.

6. The interpretation of diphosphatases as a storage of phosphorylizing enzymes in the cell is discussed.

7. The possibility that Gomori’s reaction of diphosphatases fails to show their exact localization in the cell is considered, and, as far as the present material is concerned, discarded.
Cytochemical Studies on the Embryonic Development of Drosophila melanogaster: I. Protein Sulphydryl Groups and Nucleic Acids
Authors: Yao T.
Published: April 2021

In the egg of Drosophila the distribution of sulphydryl and ribonucleic acid compounds has no apparent connexion with the dorso-ventral organization, contrary to the situation found in the amphibian egg.

Histochemical evidence suggests that the nucleic acid metabolism of the Drosophila egg may be similar to that of the chick embryo.

During embryogenesis the contraction of the germ band can be considered as an important morphogenetic stage which marks the beginning of the histo-differentiation of all larval structures.
A Critique of the Plasmal Reaction, with Remarks on Recently Proposed Techniques
Authors: Cain A. J.
Published: April 2021

1. The acetalphosphatides which are the precursors of the aldehydes (‘plasmal’) responsible for Feulgen’s plasmal reaction are extremely labile compounds wbich hydrolyse very rapidly in acid media, and are destroyed more or less rapidly during fixation. The liberation of aldehydes from them is catalysed by mercuric chloride.

2. Ordinary unsaturated lipoids, if exposed to air, become capable of producing a colour with Schiff’s reagent, which, unless a control section is

Cain—A Critique of the Plasmal Reaction 425

used, can be misinterpreted as a positive result for Feulgen’s plasmal reaction. Mercuric chloride has little or no influence over the oxidative rancidity of unsaturated lipoids.

3. Any technique prescribed for showing the plasmal reaction must avoid acid media and prolonged fixation and handling of the tissues. A control section is a necessity.
A Dye Phosphate for the Histo- and Cytochemical Demonstration of Alkaline Phosphatase, with some Observations on the Differential Behaviour of Nuclear and Extranuclear Enzymes
Authors: Loveless A. , Danielli J. F.
Published: April 2021

1. A new method is described for the cyto- and histochemical demonstration of alkaline phosphatase (monoesterase), a synthetic substrate p-nitro-benzene-azo-4α-naphthol-phosphate being employed as the sodium salt. Two methods for preparing a solution of this substance are described, and optimal conditions for enzymic hydrolysis of the ester worked out by the use of kidney sections.

2. Experiments are also described” in which the substrate has been used to demonstrate phosphatase activity in calcifying tissues of dogfish and rat.

3. The results of the experiments with rat kidney indicate that traces of end-products are necessary before the enzyme can attack this substrate.

4. When results obtained with the new substrate are compared with those obtained with β-glycerophosphate, it is found that some sites display more activity towards one substrate than to the other.

5. The cytochemical localization of phosphatase with the new substrate is not as precise as with β-glycerophosphatel
On the Significance of the Plasmal Reaction
Authors: Cain A. J.
Published: April 2021

1. Two different reactions have been confused under the name ‘plasmal’. One, the true plasmal reaction, is due, as its discoverer Feulgen showed, to the liberation of higher aliphatic aldehydes from acetalphosphatides, the reaction taking place very rapidly under the influence of mercuric chloride, the products being coloured deeply with Schiff’s reagent. The other reaction is due to the oxidation, by atmospheric oxygen, of double bonds in unsaturated fatty acid radicles. It is affected only slightly, if at all, by mercuric chloride, and increases with exposure of sections or pieces of tissue to atmospheric oxygen.

2. There is no completely satisfactory method for the histochemical demonstration of plasmal. Sections of fresh tissues are not usually suitable for cytological work, and fixation causes a reduction in intensity of the reaction. Also, the permissible fixatives are not all of the highest quality. Short fixation in a formaldehyde fixative (e.g. formal-calcium) followed by careful washing is probably the best, but the results should be compared with those obtained by the direct reaction of small pieces of fresh tissue. A suitable technique is described.
The Localization of Alkaline Phosphatase during the Post-embryonic Development of Drosophila melanogaster
Authors: Yao T.
Published: April 2021

1. The localization of alkalii1e phosphatase during the post-embryonic development of Drosophila melanogaster has been described.

2. In the larvae, nuclear phosphatase is always demonstrable, but cytoplasmic phosphatase shows a more restricted distribution. Salivary glands, mid-gut, Malpighian tubes, and pericardial cells are richest ‘in cytoplasmic phosphatase.

3. The larva prior to puparium formation is characterized by a decrease of alkaline phosphatase in the internal organs with a simultaneous increase in the hypodermis.

4. The phosphatase data support the view that the prepupa is actually an intrapuparial larval instar.

5. Pupation is accompanied, by a very noticeable increase of alkaline phosphatase which is mainly confined to the cytoplasm. The high enzyme activity is maintained for the first day and a half after head eversion: there is a subsequent decline until at the time of emergence most organs are inactive. However, certain organs retain their alkaline phosphatase activity.

6. As in embryogenesis, alkaline phosphatase seems to be more concerned with histo-differentiation than with chemo-differentiation.

7. Alkaline phosphatase (and also acid phosphatase) actively participates in the process of histolysis or cellular degeneration.

8. The alkaline phosphatase activity of the pericardial cells, together with other morphological evidence, indicates that these cells are endocrine organs which play important roles in Drosophila metamorphosis.

9. Cytochemical evidence suggests that alkaline phosphatase in Drosophila is probably playing a part in the carriage of organic substances across the membrane barrier.
A Study of the Testis Tubules, Interstitial Tissue, and Sex Characters (Thumb-pads and Wolffian Ducts) of Normal and Hypophysectomized Frogs (Rana esculenta)
Authors: Sluiter J. W. , Oordt G. J. Van , Mighorst J. C. A.
Published: April 2021

1. After hypophysectomy in October the testes and some sex characters (Wolffian ducts and thumb-pads) of Rana esculenta were investigated during 9 subsequent months.

2. The so-called prespermatogenesis (Champy, 1913) is completed normally after hypophysectomy, but the primary spermatogonia lose their capacity for division. Therefore 8 months after the operation the testis tubules contain only primary spermatogonia.

3. The spermatogonia of the testes of control frogs, kept under laboratory conditions from October onwards, show a precocious activity during the winter, but in July new spermatozoa have not yet been formed.

4. In both control and experimental frogs the spermatozoa, formed during late summer and autumn, almost entirely disappear in the spring, even in the absence of copulations.

5. During the winter and spring months the interstitial testis cells of the control frogs undergo a reduction in both number and function, and this coincides with the increased activity in the testis tubules which occurs under laboratory conditions.

6. Conversely the decreased spermatogenetic activity, caused by hypophysectomy, coincides with an increase in the number of interstitial cells. The cytoplasm of these cells, however, is greatly reduced, although the nuclei maintain their typical form and size till at least 9 months following the operation.

7. Thumb-pads and Wolffian ducts are strongly affected by hypophysectomy.

8. The cytological changes brought about in the interstitial cells of R. esculenta after hypophysectomy do not quite coincide with changes in the development of the thumb-pads and Wolffian ducts. Therefore no new evidence for the endocrine function of these cells can be given.
The Structure and Development of the Larval Cuticle of Diataraxia oleracea (Lepidoptera)
Authors: Way M. J.
Published: April 2021

The main layers comprising the soft cuticle of the Diataraxia larva have been defined and a study made of their formation during development of the 5th instar larval cuticle.

In soft cuticle the epicuticle is thrown into minute tubercles and consists of three layers—the cuticulin layer, the wax layer, and the cement layer. The cement layer lies outside or partly embedded in the wax layer, but it is either absent or extremely thin over the tips of the tubercles. A polyphenol layer is absent and it is suggested that this layer is present only in hard cuticle.

Beneath the epicuticle is a thin, lightly tanned exocuticle approximately 0.5µ thick.

The 7-10p. thick outer endocuticle is perforated by well-defined pore canals and consists of lamellae containing chitin fibres varying from 100 to 2,000 A in diameter. Pore canals are absent in the inner endocuticle which when fully developed may be more than 5oµ in thickness.

At 25° C., moulting of the 4th-5th instar takes less than 48 hours. The cuticulin layer is laid down about 12-24 hours before ecdysis. At about 6-12 hours before ecdysis the exocuticle is formed beneath the cuticulin layer in the outer part of the developing outer endocuticle. Formation of the wax layer begins about 1 hour before ecdysis, while the cement layer is secreted only a few minutes prior to ecdysis. The inner endocuticle is laid down during the 5 days after ecdysis.

Prior to ecdysis the pore canals connect the hypodermis to the epicuticle and open into the exuvial cavity at the tips of the epicuticular tubercles. Probably the pore canal lumen is responsible for conduction of the moulting fluid.

Each pore canal contains a well-defined strand of material which occupies but a small part of the pore canal lumen. Thè pore canal strands, conduct protein and dihydroxyphenol from the hypodermis to form the exocuticle. Exocuticle formation is complete by about 112 days after ecdysis. At this stage the pore canal strands become chitinized and sclerotized and the pore canals are cut off from the hvpodermis by the developing inner endocuticle. The pore canals are not responsible for transport of regenerative waxes from the hypodermis after abrasion of the epicuticle.

In areas of hard cuticle there is a relatively thick and heavily tanned exocuticle which continues to develop during the life of the instar. The pore canals maintain contact with the hypodermis throughout the instar and probably remain functional as a conducting system for transport of exocuticular materials.

A study of Verson’s glands suggested that the large gland cell secretes a lipoprotein which is discharged on the surface of the epicuticle to form the cement layer. The intercalary cell secretes a phenol which is responsible for the tanning of a plug that blocks the opening of the gland duct after discharge.
Perinuclear Sudanophil Bodies in Mammalian Epidermis
Authors: Montagna William
Published: April 2021

1. In the epidermis of laboratory mammals there are perinuclear lipid spherules which are demonstrated clearly with sudan black. The centre of the larger of these droplets is occupied by a sudanophobe core of varying dimensions.

2. The distribution of the bodies corresponds to the osmiophil elements in comparable tissues, and the structural pattern is similar to that of the Golgi elements in other tissues, as described by Baker and his associates.

3. With the exception of the skin of the monkey, the lipid bodies are negative to the acid haematein test.
A New Method for injecting the Tracheae and Tracheoles of Insects
Authors: Wigglesworth V. B.
Published: April 2021

A simple method of evacuating and injecting the tracheal system is described.

The injection fluid consists of copper, cobalt or lead naphthenate in light petroleum (‘white spirit’). This is converted to the black metallic sulphide by exposing the insect to sulphuretted hydrogen after injection.

Tracheae and tracheoles are revealed. After fixation the tissues may be cleared and mounted in Canada balsam or sectioned and stained.

Methods of bleaching dark coloured insects after injection are described.
The Structure of the Foetal Yolk-sac Splanchnopleur of the Rabbit
Authors: Morris B.
Published: April 2021

At the 16th day post coitum, a remnant of the bilaminar omphalopleur is present in the form of a short tag. The further shortening of this tag is effected by two concurrent processes ; firstly the degeneration at its free end, and secondly the pulling out of the ectodermal and endodermal epithelia of which it is composed. This latter process is accompanied by the further growth of mesoderm in the vicinity of the tag, and leads to the appearance of squamous cells in the endodermal epithelium of the yolk-sac splanchnopleur. The active production of multinucleate spherules by the chorionic ectoderm is decreasing in intensity by the 24th day. At this stage the vitello-allantoidean vessels in the mesoderm of the chorion, linking the omphaloidean and placental circulations, have mostly disappeared, only a few small vessels remaining. The apical concentration of the eosinophilic granules and mitochondria in the cytoplasm of the endodermal cells of the yolk-sac splanchnopleur, and the frequent basal position of the nucleus, suggests a secretory polarity. The manner in which the endodermal epithelium is folded and pleated suggests an absorptive function. On the side next to the exocoel the yolk-sac splanchnopleur is lined by a coelomic mesothelium of flattened cells which form a continuous pavement epithelium. The entry of circulating maternal antibodies into the foetal circulation is discussed.
The Effect of Inhibitory Substances on Cell Division: A Study on Living Cells in Tissue Cultures
Authors: Hughes A. F. W.
Published: April 2021

The effect of inhibitory substances upon cell divisions in chick tissue cultures has been studied mainly by phase-contrast cine-micrography. Fluoride and powerful -SH reactants prevent the entry of cells into prophase within I hour. Aminopterin and colchicine are complete spindle inhibitors; they prevent its formation at the end of prophase, and can act on all metaphase cells in the culture. The effect of fluoride, cyanide, and urethane on the spindle is much less drastic. Most substances can retard nuclear reconstruction in telophase to some extent, but only chloracetophenone acts in the way already described for iodoacetamide. Malonate appears to have no effect on mitosis, and fluoracetate only at very high concentrations. Possible interpretations of some of these results are discussed.