bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the Structure of the Golgi Apparatus. IV. Endostyle of Branchiostoma indicum.
Authors: Subramaniam M. K.
Published: April 2021

The work on Branchiostoma was undertaken with a view (1) to study the relation between the centi J and Golgi apparatus in a ciliated cell where the parts of the central apparatus are supposed to be associated with the cilia, and (2) also to see whether any hint as to the mode of evolution of the network can be obtained.

Each group of mucous secreting cells seems to be in a particular stage of activity. The variations in activity between the individual cells in a particular group is very small. It was observed that generally, while two groups of gland-cells are loaded with mucus, the other two are at the beginning of the secretory cycle.

The mitochondria, which appear as a few large grains in the cells at the beginning of secretory activity, break up into small granules before mucous droplets put in their appearance. Most of these mitochondrial granules are extruded with the mucus.

The Golgi apparatus occurs as a few small grains having an indefinite distribution. There is no ‘Golgi zone’, nor are these elements collected around a centriole. These increase in size and number and as they do so in many of them the central area becomes brownish. The Golgi elements finally get scattered through the cell. This scattering is soon followed by the appearance of mucus in the chromophobic areas of the elements. Increase in size of secretion droplets leads to rupture of the osmiophilic portion in regions where it is thin, and mucous globules with Golgi caps may be seen in the cytoplasm. Most of the Golgi elements degenerate, and those left behind apparently become reorganized for the next secretory cycle.

Examples and results are cited to show that the chromophobic part has nothing to do with the centrosphere. It appears difficult to decide whether the presence of Golgi apparatus in the form of discrete elements is the retention of an invertebrate characteristic by Branchiostoma.

The recent conclusions of Hirsch and Duthie are discussed, and it is shown that unless equal importance is given in future studies to the shape and structure of the Golgi apparatus and mitochondria as is at present given to the function of these cytoplasmic components we cannot accept the claims put forward by these authors. There appear to be exceptions to every rule, and in order to accept these as exceptions critical evidence is necessary.
The Alimentary Canal and Pro-epithelial Regeneration in Coccinella septempunctata with a comparison of Carnivorous and Herbivorous Coccinellids
Authors: Pradhan S.
Published: April 2021

The paper incorporates: The anatomy of the alimentary canal of Coccinella septempunctata as a type of carnivorous Coccinellid.A detailed account of the extrinsic musculature and the nerve-supply of the cephallic stomodaeum, which have been studied in very few insects and never in Coccinellids.The histology of the alimentary canal, specially the midgut, distinguishing four definite types of epithelium, one of which is surprisingly peculiar and has not been described before. This type of epithelium shows apparently two layers of cells, one superimposed over the other, the outer having large, regularly arranged, intercellular vacuoles as have not been described before, at least in the gut of insects.A discussion on the relations of the four types of epithelium to one another, recognizing that this peculiar type of epithelium is just a phase in a unique process of Pro-epithelial Regeneration in the mid-gut epithelium.A comparison of the chief characteristics of the alimentary canal of carnivorous and herbivorous Coccinellids based on the study of seven species of lady-bird beetles.Probable explanations of the differences between the alimentary canals of the carnivorous and herbivorous Coccinellids.
A Cytological Study of the Centrifuged Oocyte of the Mouse
Authors: Gresson R. A. R.
Published: April 2021

The ovaries of the mouse were ultra-centrifuged at a force of about 130,000 times gravity. The young oocyte is stratified into three layers: lightly stained cytoplasm, usually containing a few small granular Golgi elements, in the centripetal end of the cell; a middle layer of Golgi elements containing the nucleus; a centrifugal layer of mitochondria. In the larger oocytes a thin layer of yolk is present between the Golgi layer and the centripetal pole, while a layer of nongranular substance is present at the centrifugal pole. The mature oocyte is stratified into four layers: a lightly stained centripetal layer; a layer of yolk; the Golgi layer; a centrifugal layer of mitochondria. The Golgi layer is now divided into two parts; the centrifugal part contains numerous mitochondria amongst the Golgi elements. The nucleolar material is the heaviest substance in the nucleus; it increases in density with the growth of the egg. In the mature oocyte the nucleus lies in the mitochondrial layer; the nucleus is thrown towards the centrifugal pole by the weight of the nucleolus. The Golgi elements are in the form of granules, rods, and of irregularly shaped bodies. It is probable that the localized Golgi material of the mouse egg is not in the form of a network. Fat was not identified in the normal ovarian eggs, but is present in degenerating ova. The Golgi elements give rise to the fat of degenerating eggs. The inclusions and components of the follicle-cells were not always affected by the force necessary to bring about stratification of the oocyte. The degenerating eggs were not stratified.
The Golgi Apparatus and Pyrenoids of Chilomonas paramecium, with remarks on the Identification of Copromonas subtilis
Authors: Gatenby J. Brontë , Smyth J. D.
Published: April 2021

In Chilomonas paramecium the contractile vacuole is surrounded by a cortical substance (Golgi apparatus) which has the power of reducing osmium tetroxide solution and thus impregnating black (Nassonow). This cortex blackens thus in over 99 per cent, of individuals in a culture which has not been dividing. In a culture in which the individuals have been rapidly dividing, the percentage of unimpregnated contractile vacuoles increases considerably, up to about 5 per cent. During division of Chilomonas in about 70 per cent, of cases the osmiophile substance is very equally divided between the daughter cells. The dividing cortex comes away from the contractile vacuole, which eventually collapses, new contractile vacuoles arising in the site of the divided osmiophile material. In about 25 per cent, of division stages osmication of the cortex fails to a greater or lesser degree. There is always a very distinct tendency for this failure to take place even in the best of preparations. In some cases (about 3 per cent.), during division, the entire contractile vacuole and its cortex goes over whole to one individual. A new vacuole, apparently without cortex, arises spontaneously in the other individual. It is unlikely that all of these cases are due to failure of impregnation in one of the individuals, though this possibility cannot be ruled out completely. The behaviour of the original contractile vacuole cavity before separation of the daughter cells is as follows. The lipoid, having partially retreated from the vacuole, becomes separated into two parts, and the centrally placed vacuole disappears (figs. 4 and 6, Pl. 36; figs. 10 and 15, Pl. 37). New vacuoles appear in the site of the lipoid bodies in each daughter cell (fig. 5, Pl. 36). Two ellipsoidal accessory bodies or pyrenoids lie on a level with the vestibule. In older cultures the two bodies are often exactly the same size and colour (corrosive osmic followed by neutral red or haematoxylin), but in rapidly dividing cultures, one body may be of normal size, whereas the other may be absent or much smaller. During cell division, one body is carried across to each daughter. No exception to this was ever found. Identification of the smaller Peranemidae is in a confused state. Probably several species, and possibly even genera, have been described by various authors as S cy t o mon as (Copromonas) subtilis.
Studies on Lagenophrys tattersalli sp. n. (Ciliata Peritricha, Vorticellinae). Part I. Structure, Asexual Reproduction and Metamorphosis
Authors: Willis A. G.
Published: April 2021

1. The diagnostic characters of a new marine ciliate, Lagenophrys tattersalli, have been described. The lorica is chiefly distinguished by the possession of a ventral shelf, a clearly defined central cap and a marginal zone formed during metamorphosis. The adoral spiral of about two turns is distinguished by the possession of an undulating membrane.

2. The macronucleus consists of a chromatin network with a plastin component in the form of interspersed spherical plasmosomes.

3. Reserve substances are present at certain stages of the life cycle in the form of spheres composed of mixtures of fats and lipoids (chiefly cholesterol and cholesterol esters). The reserve substances accumulate during the trophic period and reach their maximum abundance prior to division.

4. Asexual reproduction takes place by two types of division leading in each case to the separation of motile organisms or swarmers and non-motile residual organisms.

5. The swarmer is always provided with a considerable quantity of fatty and lipoid reserve material. This is derived by the equal or unequal partition of the reserve material of the parent.

6. The peristome and ciliary girdle of the swarmer are formed from the division of the peristome and adoral spiral, respectively, of the parent and do not arise de novo.

7. It is maintained that the ciliary girdle of L. tattersalli does not correspond to the true ventral cilia of forms like Trichodina.

8. The ciliary girdle of the swarmer is disposed around a cavity (the sucker cavity) which was originally continuous with the vestibule of the parent. The ciliary girdle and the contractile vacuole of the swarmer are associated with the sucker cavity in the same way as the adoral spiral and contractile vacuole of the parent are associated with the vestibule.

9. In metamorphosis the sucker cavity of the swarmer becomes distended, probably by the secretion of fluid. This growth cavity, as it may be termed, increases the superficial area of the protoplasm until the dimensions of the adult lorica are attained. The marginal zone of the lorica is laid down at this period and the growth cavity afterwards decreases in size. The adoral spiral of the adult is formed from the ciliary girdle of the swarmer after the cilia of the latter have become absorbed. The growth cavity is absorbed into the vestibule.

10. The reserve materials of the swarmer are completely used up before the end of metamorphosis.
A New Method of Dissociating Cells
Authors: Goodrich Edwin S.
Published: April 2021

A method for the dissociation of the cells of Metazoan tissues is described consisting in their treatment with a saturated solution of boric acid in normal saline to which a trace of Lugol’s solution of iodine has been added. Examples of the results obtained are described and figured.
On the Pituitary of the Perch (Perca fluviatilis).
Authors: Kerr T.
Published: April 2021

1. A general description is given of the pituitary of the perch (Perca fluviatilis L.), and histological details of its various parts. The subdivisions of the glandular component are confluent with each other but distinguished by their different cell types. The nervous lobe makes contact with all three of the subdivisions, but is separated from them by a layer of connective tissue, incomplete in particular areas.

2. The anterior glandular region (anterior lobe) has an anterior chromophil and a posterior chromophobe zone. The middle glandular region (transitional lobe) possesses brightly staining acidophils and basophils as well as chromophobes. The acidophils form a dorsal sheet, deeply indented by processes of the nervous lobe, the basophils lie ventrally and posteriorly, and chromophobes are common towards the extremities of the indentations. The posterior glandular region (intermediate lobe) is elaborately penetrated by nervous lobe processes ; the cells are small and consist of amphiphils, dull basophils, and occasional dull acidophils. The possible homologies of these regions to the lobes of higher types are discussed. The nervous lobe is of loose glial tissue with many nuclei and blood vessels and some reticular and collagenous fibres.

3. Strongly acidophil spheres of various sizes and in various numbers occur in the middle glandular region. They originate in ‘sphere cells’ resembling eosinophil leucocytes and after enlarging become free in the tissues of the region. Later they appear to pass into the posterior processes of the nervous lobe to be the larger bodies of the Herring material. Finally these larger elements appear to break down to form a fine granulation, whose further fate could not be followed.
Amoeba lescherae (nov. spec.)—Its morphology, cytology, and life-history
Authors: Taylor Monica , Hayes Catherine
Published: April 2021

1. The discovery of a new species of large, free-living freshwater amoeba is recorded, and a description of the adult and of its reproduction is given. Although provisionally called Amoeba lescherae, it may have to be placed in the genus Chaos.

2. A method of cultivating it in the laboratory on a diet of small flagellates and ciliates subsisting on a pabulum of wheat grains is detailed. By starting them in Petri dishes pure line cultures are shown to be easily obtainable.

3. The resting nucleus, discoid in shape, has been shown to bear a general resemblance to that of Amoeba discoides as well as Amoeba proteus Y. Division is mitotic, and occurs once in twenty-four hours under optimum conditions. In contrast to Amoeba proteus Y the separation of the daughter amoeba is facilitated by the mechanical support of minute fragments of floating debris.

4. The cytoplasmic contents include square prismatic crystals, nutritive spheres, fat globules, neutral red bodies, and mitochondria.

5. It has been shown that while the adult has a general resemblance to Amoeba proteusY the respective developmental stages of the two amoebae are in marked contrast.

6. Agametogony is seen to begin with the emission of ‘chromidia’ from the nucleus. These chromidia form the rudiments of the agametes which differentiate into cysts. Excystationis described.

7. Agametogony occurs more frequently in Amoeba lescherae than in Amoeba proteus Y, the intervals between the ‘depression’ periods being shorter in the former than in the latter.

8. The development of the nucleus from the newly hatched amoeba to its adult condition has been traced, and the immature nucleus has been contrasted with that of species of M a y o r e l l a.
The Meiotic Phase of Calandra oryzae
Authors: Gunson Mary M.
Published: April 2021

The somatic chromosome number for the female of Calandra oryzae is twelve ; for the male, eleven. The latter is presumably of XO composition. In both sexes the haploid number of loosely paired threads is present at early diplotene. Upon condensation, the ex-conjugant chromosomes undergo a temporary complete dissociation into their univalent constituents, so that the diploid number of separate elements is reconstituted. At the equatorial plate stage the twelve univalent chromosomes associate once again into .six bivalents. In the female this is followed by a precocious separation of the anaphase chromatids, so that by the conclusion of the first meiotic division the diploid number of chromosome elements is evident at both ends of the spindle. There is no comparable process during the course of spermatogenesis; at anaphase I the haploid set of chromosomes passes to each pole, the nuclei so produced entering a resting condition.
On the Origin of the Acrosome and the Be-haviour of the Nebenkern in Diestrammena sp
Authors: Wu Chang-Chun
Published: April 2021

In the early spermatocyte of Diestrammena the Golgi material and the chondriosomes are aggregated on one side of the nucleus. During the growth period both spread out around the nucleus and become evenly scattered through the cytoplasm.

During the maturation divisions the chondriosomes, in the form of threads, surround the mitotic figure as a mantle and are distributed equally to the daughter cells during telophase. During these stages Golgi bodies could not be demonstrated by any of the methods used.

The acrosome is of multiple origin. It is formed separately from the chromophobic material of the Golgi bodies, which never fuse together to form a single acroblast, as is frequently observed in other forms. After the acrosome is complete the Golgi remnants migrate posteriorly and slough off along the tail with the cytoplasmic remnant.

The acrosome sphere migrates to the anterior pole and presses on the nuclear membrane. Within this sphere two portions of chromatic substance are formed; these fuse and elongate to form the front piece of the sperm.

As spermiogenesis goes on, the chromatin within the nucleus forms a peripheral layer inside the nuclear membrane. Finally the nucleus elongates to form the head of the sperm.

The chondriosomes condense to form the Nebenkern. This then differentiates into chromophilicand chromophobic substance. The former appears as a plate embedded in the latter and gradually decreases in amount. At the same time the central substance appears within the chromophobic substance. When the chromophilic substance has completely disappeared,, the Nebenkern divides into two equal parts. It then spins out as two series of blebs. Eventually the blebs disappear and the materials thus left twist around each other to form the sheath of the tail.

On the anterior side of the nucleus there exist some granules. Their origin and nature are doubtful. They resemble the fat droplets in the spermatid of Hemiptera. Ultimately they are sloughed off along the tail together with the cytoplasmic remnant.
Development of Olfactory Organ in Rana nigromaculata
Authors: Tsui Chi-Lan
Published: April 2021

The anlage of the olfactory placode arises from the sensory layer of the ectoderm. There is no oro-nasal groove between the olfactory placode and stomodaeum. The primitive choana opens into the endodermal part of the oral eavity. The lateral appendix is the earliest formed blind sac. It degenerates and disappears at the end of the third stage. There are three blind sacs in the larval stage: the upper, anterior lower, and posterior lower sac. The first and third sacs together become the cavum principale and recessus lateralis, while the second becomes the cavum inferius and recessus medialis in the adult stage. The nasal cavities undergo considerable shrinkage during metamorphosis. Extra blind sacs may be formed in the later larval stage. The naso-lacrymal duct arises in the dorso-lateral part of the cavum principale and extends to the lower eyelid. The process of hollowing out appears to begin from the distal end. There are four kinds of glands in the nasal cavity—medial nasal, lateral nasal, Bowman’s, and pharyngeal gland. The first one arises earlier than the other three.
The Function of Chromatocytes in the Simuliidae, with Notes on their Behaviour at the Pupal-adult Moult
Authors: Hinton H. E.
Published: April 2021

In the larvae and pupae of the Simulidae the cuticle and epidermis of the thorax and abdomen are more or less transparent, and the colour pattern is formed by cells (chromatocytes) that contain pigment granules..These cells always lie below the basement membrane. It is possible to photograph the chromatocytes without damage to the animal and thus to make photographic records of the behaviour of particular chromatocytes over a period of many days when the animal is moving about and feeding in the normal way.

The chromatocytes accumulate lipids. The accumulation of lipids during larval growth and their depletion during adult development has been photographed in normal undamaged animals.

Conspicuous changes in the colour pattern, especially of the thorax, occur at metamorphosis. Such changes are due to mass migrations and the formation of new aggregation patterns by the chromatocytes. While such movements of the chromatocytes are taking place in some parts of the body, the aggregation patterns of chromatocytes in other parts of the body remain unchanged and appear to be unaffected by the events that initiate and accompany moults and ecdyses.
A Study of Rawitz’s ‘Inversion Staining’
Authors: Przełęcka Aleksandra
Published: April 2021

The Rawitz method involves mordanting with tannic acid and potassium antimony tartrate, and staining with basic fuchsine. The mordanting causes basic fuchsine to act as though it were an acid dye (‘inversion staining’).

A modification of the method is described in the present paper. This modification makes it possible to obtain the same results in a shorter time.

The chief substances stained by Rawitz’s method are phospholipids, certain proteins, and certain polysaccharides.

Although the method cannot be regarded as a cytochemical test in the strict sense, yet it gives useful indications of chemical composition and in addition is valuable to the morphological cytologist as a technique for showing certain cytoplasmic inclusions (mitotic spindle, acrosome, mitochondria, ‘Golgi apparatus’ of certain cells).
The Histology of the Nervous System of anInsect Rhodnius prolixus (Hemiptera): I. The Peripheral Nervous System
Authors: Wigglesworth V. B.
Published: April 2021

While studying the osmium/ethyl gallate method of fixation and staining (Wigglesworth, 1957) a number of incidental observations were made on the nervous system of Rhodnius. This staining method reveals particularly those structures most rich in lipids, the cell membranes, fat droplets, mitochondria, and ‘Golgi element’, giving a picture which closely resembles that seen with the electron microscope. This appearance is so different from that shown by standard methods of staining, that it seemed worth while to re-investigate the histology of the nervous system of the insect by its use. That should provide a useful background to the electron microscope studies being made at the present time. In this paper, the first of three which are projected, certain parts of the peripheral nervous system are described.
An Improved Radioautographic Method for demonstrating Tyrosine Uptake and Tyrosinase Activity in Melanocytes
Authors: Brunet P. C. J. , Small P. L.
Published: April 2021

A method for studying the melanogenetic activity of pigment cells is described. Tissue is incubated in a medium containing tyrosine labelled with I4carbon. Tyrosine, being a precursor of melanin, is incorporated into the insoluble pigment. This can be detected in histological selections by radioautography. A measure of tyrosine uptake and, provided precautions are taken, of tyrosinase activity, can be gained by the use of this technique. There are advantages in using labelled, rather than ‘cold’ substrate.

This technique, developed by other workers, has been used with success; but difficulties arise in situations where intense pigmentation obscures the image of the superimposed radioautograph. Here consideration is given to the possible methods for circumventing this difficulty, and a satisfactory method for partially bleaching the pigment, without upsetting the radioautograph, is described in detail.
The Small Leg-nerve of Spiders and a Probable Mechanoreceptor
Authors: Parry D. A.
Published: April 2021

Besides the main leg-nerve there is, in spiders, a ‘small leg-nerve’ which is mainly sensory. About 8 of the fibres arise from neurones which form a ganglion at the femur-patella joint and appear anatomically to be joint mechanoreceptors, but if so must supplement the lyriform organs. Cutting the small leg-nerve has no effect on the walking pattern nor on the detection of prey, which almost certainly depends on mechanoreception. The small leg-nerve contains one motor fibre which innervates the claw elevator. This muscle has a double innervation, a second fibre running in the main leg-nerve. There are interesting parallels between the small leg-nerve in spiders and Limulus.
The Ligament of the Lucinacea (Eulamellibranchia)
Authors: Allen J. A.
Published: April 2021

The basic structure of the opisthodetic ligament of the Lucinacea consists primarily of inner layer, anterior and posterior outer layers, and periostracum. This is secondarily extended by fused periostracum and fusion layer. Fused periostracum extends as far as the posterior adductor muscle and, except in the Ungulinidae, to the anterior adductor. The fusion layer covers the posterior outer layer and a little beyond. Only in Loripes lucinalis is the fusion layer to be found anteriorly. Below the umbos the inner layer, posterior outer layer, and overlying fusion layer are split. This split can be explained in terms of the growth and form of the shell. The anterior outer layer fills the split and extends to the anterior limit of the lunule. The ligament, external in the Ungulinidae, becomes progressively more internal. At the same time the posterior limit of the outer layer becomes modified as a result of the elongation of the outer surface of the outer mantle fold between the pallia! lobes in the depth of the posterior mantle embayment. The Lucinidae are most specialized in this respect where, in L. lucinalis, a tongue of tissue divides much of the ligament horizontally. The Thyasiridae, the remaining family of the group, occupies an intermediate stage in this specialization.
Patterns of Myo-neural Junctions and Cholinesterase Activity in the Muscles of Tadpoles of Xenopus laevis
Authors: Lewis P. R. , Hughes A. F. W.
Published: April 2021

A simultaneous coupling azo dye technique has been used to reveal the distribution of cholinesterase activity in the musculature of the developing tadpole of Xenopus laevis. The use of inhibitors and a less convenient but more specific histochemical technique confirmed that only true cholinesterase distribution was being demonstrated; and a study of silver-impregnated material proved that this azo dye technique provides a very convenient method of following the development of the patterns of myo-neural junctions in the striated muscles of this tadpole. A wide variety of patterns is seen in the various muscles; in the axial musculature the muscle-fibres become innervated at their ends from myocommatal plexuses and never acquire endings along their length; broad muscular sheets, as in the walls of the branchial and abdominal cavities, are also first innervated terminally from the septa but later acquire secondary patterns of innervation over their surfaces; while in long narrow muscles the main innervation is along the lengths of the fibres. These different patterns of innervation are correlated with the functions of the various types of muscle. It is suggested that terminal innervation may be a special adaptation to permit rapid establishment of neurogenic activity, the pattern of endings of the more usual type forming when the need for precisely co-ordinated reflexogenic activity arises. In some muscles, the azo dye technique reveals a profuse multiple innervation of the fibres which are assumed to be of the so-called ‘slow type’ known to exist in some amphibian muscles.
The Structure of the Nervous System in Velella
Authors: Mackie G. O.
Published: April 2021

Silver staining methods have been applied to the nervous system of Velella, Two histologically distinct plexuses are described under the headings ‘open’ and ‘closed’ systems. The open system consists of neurones with fine processes which run for distances of up to 2 mm, retaining their independence ins pite of frequent contacts with other fibres. The fibres of the closed system are large and run together, forming a nerve-net in which neurofibrillar material from different neurones intermingles; it is provisionally to be regarded as a syncytium. A certain type of ‘fibre’ in this system is believed to arise secondarily by the drawing out of adhesion connexions into long strands. Free nerve-endings resembling growing-points occur in both systems. The two systems occur throughout the ectoderm, but in the invaginated ectoderm the open system is poorly developed. The functions of the two systems are not known, but the closed system is probably specialized for through-conduction.

Neuro-sensory cells occur in the external ectoderm, making contact with fibres of both open and closed systems. No specialized endings have been found in a muscular region examined. No nerve-rings or centres have been found. Nerves are sparsely distributed in the endoderm, but they lie independently of one another and of ectodermal nerve-fibres crossing the mesogloea between the invaginated and external ectoderm layers.
The Ligamentary System and the Segmental Musculature of Nephtys
Authors: Clark R. B. , Clark M. E.
Published: April 2021

Nephtys lacks circular body-wall muscles. The chief antagonists of the longitudinal muscles are the dorso-ventral muscles of the intersegmental body-wall. The worm is restrained from widening when either set of muscles contracts by the combined influence of the ligaments, some of the extrinsic parapodial muscles, and possibly, to a limited extent, by the septal muscles. Although the septa are incomplete, they can and do form a barrier to the transmission of coelomic fluid from one segment to the next under certain conditions, particularly during eversion of the proboscis.

Swimming is by undulatory movements of the body but the distal part of the parapodia execute a power-stroke produced chiefly by the contraction of the acicular muscles. It is suspected that the extrinsic parapodial muscles, all of which are inserted in the proximal half of the parapodium, serve to anchor the parapodial wall at the insertion of the acicular muscles and help to provide a rigid point of insertion for them.

Burrowing is a cyclical process involving the violent eversion of the proboscis which makes a cavity in the sand. The worm is prevented from slipping backwards by the grip the widest segments have on the sides of the burrow. The proboscis is retracted and the worm crawls forward into the cavity it has made. The cycle is then repeated.

Nephtys possesses a unique system of elastic ligaments of unusual structure. The anatomy of the system is described. The function of the ligaments appears to be to restrain the body-wall and parapodia from unnecessary and disadvantageous dilatations during changes of body-shape, and to serve as shock-absorbers against the high, transient, fluid pressures in the coelom, which are thought to accompany the impact of the proboscis against the sand when the worm is burrowing. From what is known of its habits, Nephtys is likely to undertake more burrowing than most other polychaetes.
The Effects of Ultraviolet Irradiation on Uncleaved Eggs of Xenopus laevis
Authors: Gurdon J. B.
Published: April 2021

The effects are described of ultraviolet (u.v.) irradiation upon the eggs of Xenopus laevis. The results obtained apply to fertilized eggs and also to unfertilized eggs into which blastula nuclei have been transplanted. Eggs were irradiated up to 20 min after laying, for periods varying from 15 to 50 sec.

The egg nucleus is completely inactivated by small doses of u.v. If fertilized eggs are used this gives rise to haploids, which the use of a nuclear marker has shown to be androgenetic. After irradiation the egg nucleus descends towards the centre of the egg, and comes to lie adjacent to the transplanted or sperm nucleus. At the first mitosis, however, it does not fuse but remains as a pycnotic clump in the centre of the spindle. Soon after this it disappears, without disintegrating into visible fragments. The transplanted or sperm nucleus appears to be unaffected by the irradiation and death of the egg nucleus.

The egg cytoplasm does not appear to be damaged, even after doses of u.v. which are considerably more than sufficient to kill the egg nucleus. The main reasons for this belief are that haploids obtained by other means develop no better than those obtained by u.v. An increase of u.v. treatment from 30 to 80 sec results in no increase in abnormalities sustained.

The jelly is broken down and the vitelline membrane weakened. This enables the egg to be penetrated by a micropipette without causing damage or preventing healing.

This investigation was undertaken to facilitate the analysis of nuclear transplantation experiments in Xenopus. The increased penetrability of eggs is of technical value for this purpose. The interpretation of these experiments is greatly facilitated by the knowledge that the egg cytoplasm need not be damaged by the u.v. and that the egg nucleus is completely inactivated so as not to interfere with the development of the egg.
The Electron Microscopy of the ‘Golgi Apparatus’ in the Purkinje Cells of Owls
Authors: Malhotra S. K. , Meek G. A.
Published: April 2021

The classical site of the ‘Golgi apparatus’, the Purkinje cells of the cerebellum of owls, has been examined by electron microscopy. The greater part of the cytoplasm consists of aggregates of closely packed granular membranes of endoplasmic reticulum. The objects described by Dalton and Felix in electron micrographs and called by them the Golgi apparatus are rarely seen in these preparations. It seems likely that the ‘Golgi apparatus’ of this cell as seen in the optical microscope is formed by the de- position of silver or osmium on the membranes of the endoplasmic reticulum, which form a network throughout the cytoplasm of this cell.
The Early Post-moult Cuticle in Buthus
Authors: Krishnakumaran A.
Published: April 2021

The cuticle of the scorpion, Buthus tamulus, has been studied at the early postmoult stage. There is a distinct two-layered epicuticle, which is non-chitinous, and a procuticle consisting of a chitin/protein complex. Polyphenols, phenolase, and sulphur are present at this stage. Quinones and groups containing sulphur seem to play a part in the subsequent hardening of the cuticle.
The Histology of the Neurosecretory System of the Adult Female Desert Locust, Schistocerca gregaria
Authors: Highnam K. C.
Published: April 2021

The pars intercerebralis of the brain of the desert locust contains about 2,400 cells in two groups, which stain with chrome-haematoxylin-phloxin and with paraldehydefuchsin. On the basis of differences in size and staining reactions, four types of cell, called A-, B-, C-, and D-cells may be differentiated. The A- and B-cells produce different kinds of material; they are not thought to be stages in a secretory cycle. The C- and D-cells are probably not neurosecretory. The corpora cardiaca are divided into two regions. One part stores neurosecretory material from the pars intercerebralis and the other is glandular in appearance. Material discharged from the A- and B-cells in the immature female passes along the nervi corporis cardiaci I to the anterior parts of the corpora cardiaca. The mature female is characterized by the presence of very much larger amounts of material in the corpora cardiaca, in the nervi corporis cardiaci I, and in the A-cells of the pars intercerebralis. The significance of this larger amount of material with respect to neurosecretory cell activity is discussed.
A Comparative Histochemical Study of the ‘Golgi Apparatus’
Authors: Malhotra S. K.
Published: April 2021

The purpose of this investigation was to find out the responses of Golgi’s net in the neurones of vertebrates to various dyes and histochemical reagents, and to compare these responses with those given by the ‘dictyosomes’ of the cells of invertebrates. Dictyosomes are regarded by many cytologists as the homologue of Golgi’s net. The young oocyte of Limnaea stagnalis was chosen as a cell that possesses typical dictyosomes, which have recently been examined by histochemical methods.

The object that presents the characteristic Golgi pictures in the neurones of vertebrates is essentially different, not only in ultrastructure but also in its chemical composition, from those that represent in life the ‘dictyosomes’ of invertebrates. The dictyosomes of the oocyte react positively to tests for phospholipid and cerebroside, whereas Golgi’s net is negative to these tests. Tests for arginine and for ribonucleic acid are positive for Golgi’s net, but not for the dictyosomes of the oocyte. The dictyosomes are intensely stained by Rawitz’s inversion staining technique and also by acid fuchsine (Metzner) and by iron haematoxylin, but these techniques do not show the net in the neurones of vertebrates. Golgi’s net is resistant to embedding in paraffin after fixation in Clarke’s (Carnoy’s) fluid, but the dictyosomes are not. Neutral red is taken up during life by the object representing the dictyosomes, but not by the net of Golgi.
The Iridophores of the Echinoid Diadema antillarum
Authors: Millott Norman , Manly Brenda M.
Published: April 2021

The blue pattern seen when the skin of Diadema antillarum is viewed by reflected light is due to iridophores. The quality of their blueness varies with the background provided by neighbouring chromatophores.

Microdissection reveals that they consist of gelatinous plates contained in a fibrous and cellular capsule. The study of fixed preparations shows that the plates are sheathed and that their structure is greatly altered by fixation which distorts, disrupts, or dissolves them.

The structure of the iridophores bears little resemblance to the description of the so-called ‘eyes’ of D. setosum given by Sarasin and Sarasin, with which they appear to correspond.

Examination of their optical properties indicates that Rayleigh scattering by the colloidal contents is the most likely cause of their colour.
Coloration of the Golgi-Nissl Network in a Vertebrate Neurone by Sudan Black
Authors: Malhotra S. K.
Published: April 2021

Though it is generally considered that the cytoplasmic inclusions, commonly described as ‘Golgi apparatus’, contain phospholipid, the routine histochemical tests for lipid do not reveal the apparatus in the neurone of vertebrates. A technique for colouring the apparatus in the neurones of vertebrates with Sudan black is described in this paper.
A New Automatic Machine for staining Histological Sections
Authors: Dilworth S.
Published: April 2021

A machine is described for the automatic staining of sections of tissue, mounted on microscope slides. It is narrow and compact, and can be placed along the back of a bench or on a shelf. Although for the present purpose the machine is designed to accommodate up to 26 tanks, any number less than this may be used. A rack holding 30 slides is attached to a carrier, which then conveys it through the various solutions, according to a predetermined programme.
A Study of the so-called ‘Chloride-Secretory’ Cells of the Gills of Teleosts
Authors: Vickers T.
Published: April 2021

The histology of the gills of a normally freshwater teleost, the guppy (Lebistes reticulatus), has been studied after the fish had been subjected to various concentrations of sodium chloride. Cells similar to those identified by previous workers as ‘chloride- secretory cells’ develop in response to adaptation to hypertonic salt solutions, and the number and character of the cells can be related to the salt load and to the degree of adaptation of the fish to it. The cytology of these cells has been shown to be consistent with their supposed function. In fish which are not fully adapted to the salt load, these cells show signs of the formation of mucous materials, and under extreme conditions they may undergo transformation into goblet cells. This may provide an explanation of the failure of Bevelander (1935, 1936) to find any specialized cells other than mucous cells on the teleost gill.
The staining of nervous elements by the Bodian method I. The influence of factors preceding impregnation
Authors: Williams Terry
Published: April 2021

The stainability of neural elements is determined during the various stages of tissue preparation which precede impregnation.

The hypothesis (Romanes, 1950) that variations in the physiological state of the neurones at the time of fixation might influence the stain was examined. Feeding and anaesthesia did not influence the staining of gastric nerve fibres under the conditions of the experiments.

A study was made of fixing fluids for Bodian staining. A picric-acetic-alcohol mixture and alcoholic Bouin were convenient and effective, each being superior to formaldehyde-acetic-alcohol. For overnight fixation formaldehyde solution neutralized with calcium carbonate was satisfactory, but where prolonged fixation is permissible formaldehyde neutralized with excess of magnesium carbonate gave superior results.

Attention was drawn to the probability that the final stain could be improved by ‘pretreatment’ of mounted sections before silvering. Dewaxed sections were treated individually with 27 substances from a variety of chemical groups to determine the effects on subsequent Bodian staining. Nitric and sulphuric acids, formaldehyde solution neutralized with magnesium carbonate, methyl alcohol, and perhaps sodium carbonate contribute in different ways towards better preparations. In particular pretreatment with nitric acid suppresses the background stain, especially in smooth muscle; sulphuric acid increases the number of fine nerve fibres displayed, and methyl alcohol facilitates the staining (in formaldehyde-fixed tissues) of nerve fibres that are otherwise difficult to demonstrate, such as those in the renal cortex, which are almost certainly post-ganglionic sympathetic fibres.
Neurosecretory cells in the optic tentacles of certain pulmonates
Authors: Lane Nancy J.
Published: April 2021

Cells considered to be neurosecretory have been observed in the optic tentacles of certain stylommatophoran pulmonates. Such cells are divisible into three distinct types, of which those called the ‘collar’ cells surround the central digitate ganglion and eye. The other two types, the ‘lateral oval’ and the ‘lateral processed’ cells, lie laterally in the tentacle, on the inner edge of the outer dermo-muscular sheath. All three cell-types have branching dendritic processes, containing granules. The dendrites of the collar and of the lateral cells apparently extend from the cell-body to the surface of the epithelium. The axonal processes of all three types are thick and contain granules.

The ground cytoplasm of these cells is scarcely visible owing to the great number of homogeneous, spheroidal granules that are present. The granules are sudanophil, and the ones in the collar cells contain phospholipid (probably cerebroside as well). All three types of cells contain a much smaller number of lipid droplets, with sudanophil and osmiophil externum and sudanophobe and osmiophobe internum; these are dispersed through the cytoplasm. Special ‘perinuclear bodies’, also binary in structure, are present in the collar cells and lateral oval cells.

Cells of the types described in this paper have not been found in other sub-classes of the Gastropoda, nor in the Basommatophora, but only in the pulmonate order, Stylommatophora. They appear to form an area of active neurosecretion in the re-tractile tentacles of these animals.
A modification to the Huxley ultramicrotome
Authors: Mcgee-Russell S. M. , Roberts F. H. , Jacobs J. K.
Published: April 2021

The mechanism of advance of the Huxley ultramicrotome was modified by the addition of appropriate gearing to facilitate the routine preparation of ½ to 2 μ sections for phase contrast or interference microscopy as an adjunct to the study of thin adjacent sections by electron microscopy. The plate depicts the nature of the modification.
The nucleolar organizer in the mitotic chromosome complement of Xenopus laevis
Authors: Kahn J.
Published: April 2021

The mutation which reduces nucleolar number in interphase nuclei of Xenopus laevis also reduces the number of secondary constrictions in mitotic chromosome complements.
An investigation of the anomalous staining of chromatin by the acid dyes, methyl blue and aniline blue
Authors: Mckay R. B.
Published: April 2021

Methyl blue and aniline blue, though acid dyes, stain the chromatin of the spermatogenetic cells of the mouse (especially of the primary spermatocytes) strongly. Extraction of the basiphil nucleic acid constituents from the chromatin causes loss of this property, while destruction of acidophilia in the protein constituents does not. It has been concluded that the dyes interact with the nucleic acids. Further, they appear to react with both DNA and RNA in the chromatin, although they show no affinity for the cytoplasm of the exocrine cells in sections of pancreas, which is rich in RNA.

The mechanism of the reaction has not been fully elucidated, although apparently the dyes do not behave as basic dyes towards the nucleic acids, and the interaction is non-ionic. Methyl blue and aniline blue stain strongly other ‘acidic’ substrates, such as cellulose and nitrocellulose, and attempts have been made to relate the staining of nucleic acids to the staining of these substrates, particularly cellulose; for the staining properties of this substrate have been intensively investigated elsewhere. No satisfactory correlation, however, has been obtained, for nitrocellulose has been found to be less strongly stained at pH 3·0 than at pH 7·1, while the reverse is true for cellulose. Further, only one of 3 direct cotton dyes used appears to have any affinity for the chromatin of the spermatogenetic cells. Direct cotton dyes have large flat molecules with a high degree of conjugation. It is suggested that these characteristics are essential for interaction with nucleic acids, and also that the molecule must be reasonably compact.

Finally, it has been shown that methyl blue, aniline blue, and 3 direct cotton dyes of the azo type have no ability to stain the glycogen in liver cells, yet glycogen is very closely related to cellulose.
The control of dragline spinning in the garden spider
Authors: Wilson R. S.
Published: April 2021

A study of the tarsal claws, the spinning apparatus, and other factors affecting dragline spinning has been made using certain orb-web spiders, principally Araneus diadematus. The structure of the tarsal claws suggests that they are incapable of smoothly controlling the speed at which the silk thread is extracted, although they can grip and release the thread quickly.

Evidence is presented that smooth control of spinning is achieved through the interaction of the intra-abdominal pressure and the control valve which lies in the silk duct. The intra-abdominal pressure is shown to be equivalent to from 3 to 4 cm of mercury, and to be responsible for moving the fluid silk out of the gland and up the duct. The experimental results also suggest that the control valve regulates the amount of fluid silk available for spinning as a thread and that it also acts as the functional spinning orifice, its aperture controlling the diameter of the thread spun.
The fine structure of the cortical layers in Paramecium aurelia
Authors: Stewart John M. , Muir Alan R.
Published: April 2021

Paramecia have been cultured in 5 % iron-dextran solution for several days, but under the present experimental conditions do not appear to synthesize the iron-storage protein ferritin.

High resolution electron micrographs were obtained of the outer ‘pellicular’ and inner ‘peribasal’ membranes of the cortical layer in Paramecium aurelia; both membranes proved to be triple-layered unit membranes, each having two osmiophilic layers 2 to 3 mμ thick separated by a space of 3 mμ- The outer membrane of the cilium has the same structure as, and is continuous with, the pellicular membrane. This fact is thought to be of significance with regard to antigen studies.