bluuebunny/crossref_metadata_2025 huggingface dataset:
Loxosoma loxalina and Loxosoma saltans —Two New Species.
Authors: Assheton Richard
Published: April 2021

The genus Loxosoma is remarkable among Polyzoa in having the lophophore placed more or less obliquely to the main axis of the stalk instead of being at right angles as in other Polyzoa, and in being solitary, for the buds, which are formed readily enough, drop off before they have reached any great size, and attach themselves to the surface of some other organism or neighbouring object by means of diverse forms of adherent arrangements in the end of the stalk or foot, which varies a good deal in shape. The species, of which rather more than a dozen have been described, are all commensals living fixed on to other organisms or upon the tubes inhabited by other organisms, which may be Polychætes, Sponges, Ascidians, Gephyreans, and probably other animals as well.
Stolon Formation in Certain Species of Trypanosyllis
Authors: Potts F.A.
Published: April 2021

In 1896 a single specimen of a Syllid Polychæt was discovered by the Columbia University Expedition to Puget Sound, in which the reproductive individuals or stolons were produced from the ventral surface of the last two segments to the number of fifty or more, arranged in a compact rosette instead of such a linear chain as occurs in Autolytus or Myrianida. This was described by H. P. Johnson (1) as Trypanosyllis gemmipara. For another unique example exhibiting a similar phenomenon, collected by Harold Heath in California, he instituted the species Trypanosyllis ingens (3). Since then two other species have been discovered which reproducein the same manner—T. misakiensis, by Izuka, in Japan (4), and T. crosslandi, by Cyril Crossland, at Zanzibar, which is here fully described for the first time.
Further Observations on the Intestinal Trypano-plasmas of Fishes, with a Note on the Division of Trypanoplasma cyprini in the Crop of a Leech
Authors: Martin C. H.
Published: April 2021

In a previous paper in this journal (‘Quart. Journ. Micr. Sci.,’ vol. 55, 1910) I have given a fairly detailed account of the morphology and method of division of the normal active form of Trypanoplasma congri.
The Development of the Heart and Vascular System of Lepidosiren paradoxa
Authors: Robertson Jane I.
Published: April 2021

In the following account of the development of the heart and blood-vessels of Lepidosiren paradoxa I have endeavoured to trace their main morphological rather than their minute anatomical relations. I trust that few points of importance have been neglected, though probably many minutiæ of interest have been passed over.
Stops recommended for Oblique Illumination with the Achromatic Condenser
Authors: Richardson Wills
Published: April 2021

The attempts to resolve the markings of certain diatoms with oblique light are frequently attended with considerable difficulty, so much so that the management of oblique illumination requires very great patience to prevent failure. One moment the field is too milky, at another the glare is most distressing, next the valves are too thick, and at last, after a great deal of trouble and strain of vision, a tolerably good view is obtained. But, on the other hand, we may not be so fortunate, and, notwithstanding all our perseverance, complete failure in procuring a satisfactory demonstration is often experienced. Of course, I assume that the object-glasses are properly adjusted, a neglect of which is of itself sufficient to interfere with the delineation.
The So-called Labial Cartilages of Raia clavata.
Authors: Allies Edward Phelps
Published: April 2021

Gegenbaur (1872), in his classical work on “Das Kopfskelet der Selachier,” describes (1. c., p. 216), in Raia (species not given) and Raia vomer, two cartilages which he considers to be the homologues of the labial cartilages of Selachii. In Raia (species not given), which is the one first described, one of these two cartilages is shown lying-definitely nearer the anterior end of the ventral surface of the snout than the other cartilage, and, doubtless because of this, the former cartilage is called the anterior upper labial and the other the posterior upper labial. The so-called anterior labial lies, however, farther from the symphysis of the upper jaw and. farther from the upper edge of the mouth than the so-called posterior one, and if the mouth were terminal it would be the posterior instead of the anterior cartilage. Doubtless because of this, Gegenbaur says (l.c., p. 218) that it is evident that the so-called anterior upper labial of the Batoidei corresponds to the posterior upper labial of the Selachii, and the posterior upper labial of the Batoidei to the anterior upper labial of the Selachii. The posterior (oral) edge of the posterior labial is shown (l.c., Pl. 17, fig. 1) in contact, its full length, with the palatoquadrate; its anterior (aboral) edge is said to be bound to the posterior (oral) edge of the anterior labial; and the lateral (absymphysial) end of the latter cartilage is said to be in contact with the palatoquadrate. There is accordingly no space either between the adjoining edges of the two cartilages, or between their posterior (oral) edges and the palatoquadrate, and the nasal groove (Nasenrinne) must accordingly lie either wholly lateral (absymphysial) to both labials or external to them.
The Development of the Starfish Crossaster papposus, Muller and Troschel.
Authors: Genimill James F.
Published: April 2021

The development of Crossaster papposus, though less important than that of starfish having feeding larvæ, nevertheless presents features of great interest, especially in regard to the origin of the primary larval cœlomic cavities, the madreporic vesicle, the extra rays, the skeleton, and the general modifications due to yolkiness of the egg. Crossaster papposus much resembles Solaster endeca in development, and accordingly I may be allowed to refer to a former paper on the latter (7) for details and illustrations-which do not call for repetition (see, e.g., p. 3 and p. 34).
On the Development of the Hypobranchial, Branchial, and Laryngeal Muscles of Ceratodus. With a Note on the Development of the Quadrate and Epihyal
Authors: Edgeworth F. H.
Published: April 2021

As is well known, Wiedersheim stated that laryngeal muscles exist in Lepidosiren and Protopterus, but are absent in Cera- todus. He admitted, however, that the specimen investigated was badly preserved.

In a recently published paper (1920) on the laryngeal muscles of Amphibia, I suggested that, possibly, they might be found in better specimens. Owing to the skill and perseverance of Dr. Bancroft I have come into possession of some well-preserved heads, and also of a series of embryos up to the stage of 30 mm. in length for purposes of investigation. The material also enabled me to examine the development of the hypobranchial and pharyngeal muscles, which, together with other structures, have been the subject of an elaborate memoir by Greil. In the description given by Semon of the development of Ceratodus the embryos were depicted in a series of stages numbered from 1 to 48, the last mentioned and oldest stage described being an embryo of 17-8 mm. Greil’s description is based on Semon’s stages, and also extended to stage 48. The embryos described in this paper had been fixed in formalin, and their lengths are given in millimetres. Their relation to Semon’s stages will be found in an appendix.

A tabular statement of the synonyms of the names employed has also been appended.
The Development and Homologies of the Mouth-parts of the Head-Louse
Authors: Fernando Wilfred
Published: April 2021

Mandibles, first maxillae, and labium appear in the germband at an early stage. The rudiments of the first maxillae unite to form the dorsal stylet, while those of the labium unite to form the ventral stylet. The hypopharynx arises below the first maxillae or dorsal stylet; it becomes tubular and is transformed into the salivary duct. The stylet sheath arises from the integument as a raised lip; it surrounds the dorsal and ventral stylets. The labrum persists as the upper half of the buccal funnel. The mandibles are throughout in a rudimentary condition; they disappear in the adult without becoming chitinized.
Studies on the Germ-cell Cycle of Cryptocotyle lingua: II. Germinal Development in the Larval Stages
Authors: Cable Raymond Millard
Published: April 2021

The writer’s earlier study (Cable, 1931) on the germ-cell cycle in the adult stage of Cryptocotyle lingua is supplemented by an investigation of germinal development in the larval stages occurring in the marine snail, Littorina littorea. The miracidium-mother-sporocyst was not found although very young rediae were abundant in the material studied. The primordial germ-cells of the young redia are observed in an undifferentiated condition in the body-cavity, which is not well defined due to an abundance of connective tissue. After a period of differentiation, including growth, progressive nuclear changes, and condensation of cytoplasm, the germ-cells multiply by equal division, a process which is interpreted as polyembryony. Germinal differentiation exhibits a distinct anterior-posterior gradient. The mature germinal cells give rise directly to cercarial embryos without germ-mass formation and dissociation or any matmation processes. Although germinal lineage may be traced in the redia, it seems to be interrupted in the cercaria, due to delayed segregation of germ-cells. The soma of the redia does not produce germ-cells at any stage. Evidence is afforded by this and other studies that germinal lineage with sudden intercalations of polyembryonie stages (germ-masses) cannot explain the germinal cycle of the trematodes as a group. In an alternative hypothesis, based on the phylogeny of the Digenea, it is suggested that the ancestors of this group became sexually mature in the mollusc and completed the cycle in that host, possibly before the appearance of vertebrates ; and that, with the evolution of the trematodes, sexual phenomena have gradually been lost, while accessory stages and new hosts have been included in the life-cycle. Cryptocotyle lingua is assumed to have been modified to an intermediate extent since sexual reproduction, germ-masses, and the maximum number of intercalary stages are lacking in the larval generations.
The Structure of the Somatic Chromosomes of Alstroemeria and Bomarea.
Authors: Jane Frank W.
Published: April 2021

The exceptionally large chromosomes of Alstroemeria and Bomarea furnish good material for study; an attempt has therefore been made to trace the changes which occur in these bodies during the mitotic cycle. Other genera of the same section of the Amaryllidaceae (Hypoxidoideae) have been examined with the same end in view, but with less success owing to their chromosomes being smaller. The somatic nuclei of Alstroemeria and Bomarea are almost identical, but differ, as Whyte (43) has shown, in that those of the latter genus contain eighteen chromosomes, whereas there are sixteen in the somewhat larger nuclei of the former. Although no attempt has been made to follow the history of mitosis in any one species, this has been traced with tolerable completeness in Bomarea multiflora; a number of species of both genera has been examined.
The early Embryology of a viviparous Psocid
Authors: Fernando Wilfred
Published: April 2021

The formation of germ-layers in the Psocontera has not so far been studied, and the purpose of the present paper is to fill in this gap in our knowledge of the embryology of Insects. The Psocid studied is viviparous, a condition which does not seem to have been noted so far in this group, so a brief note on the method of nutrition of the embryo is given. No attempt is made here to deal with detailed organogeny as this has been done thoroughly in other Insects.
The Physiology of Ecdysis in Bhodnius Prolixus (Hemiptera). II. Factors controlling Moulting and ‘Metamorphosis’
Authors: Wigglesworth V. B.
Published: April 2021

In the blood-sucking bug Rhodnius prolixus there are five nymphal stages, throughout which the morphological characters remain comparatively constant. At the fifth moult, when the insect becomes adult, there are striking changes in all parts of the body. It is convenient to refer to the appearance of these adult characters as ‘metamorphosis’—though without suggesting that this change is exactly homologous with meta-morphosis in endopterygote insects. Thus in the growth of Rhodnius there are two distinct phenomena to be considered : simple moulting, and moulting coupled with metamorphosis. In a previous paper (Wigglesworth, 1933) the histological changes in the epidermis during moulting and metamorphosis have been described ; in the present paper an attempt will be made to analyse some of the factors which regulate these processes.
Observations on the Embryology of Corynodes pusis (Coleoptera, Chrysomelidae)
Authors: Paterson Nellie F.
Published: April 2021

A study of the embryology of Corynodes pusis Marsh was decided upon in order that its development might be compared with that of Euryope terminalis Baly, which the writer had recently (1931, 1932) dealt with in considerable detail. Several features in the ontogeny of the latter species, including the maturation divisions of the female pronucleus and the method of formation of the mesenteron, had proved of interest, and it was felt desirable that further observations be carried out on some related species in order to determine if these phases were merely isolated developmental occurrences peculiar to Euryope terminalis, or if they would be recognized in similar stages of any other species of the Chrysomelidae.
The Giant Nerve Fibres and Epistellar Body of Cephalopods
Authors: Young John Z.
Published: April 2021

In Decapod Cephalopods there is a system of giant fibres probably serving to produce the rapid contractions of the mantle 1Bacq (‘Nature’, 136, 1935) has recently shown that acetyl choline is present in large amounts in the C.N.S. of Octopus. muscles and ink-sac by means of which the animal shoots backwards behind a cloud of ink. The giant fibres in the stellar nerves arise in the stellate ganglion, not from single giant cells, but as syncytia, by the fusion of the processes of a large number of cells. In L o 1 i g o forbesi all the cells giving rise to the giant fibres of the stellate ganglion are connected together into a giant fibre lobe. In Octopods there are no giant fibres, but in the position of the giant fibre lobe there is a small closed vesicle, pigmented yellow in some species, and named the epistellar body. In the walls of this body there are curious cells, the neurosecretory cells, whose general structure resembles that of neurons, but whose inner processes (axons) end blindly, embedded in a homogeneous substance which fills the cavity. The neurosecretory cells are innervated by a small nerve which reaches them from the mantle connective. After removal of both epistellar bodies from Eledone moschata the animal shows general muscular weakness for some days. It is suggested that the epistellar body has arisen from the giant fibre lobe, and that the neurosecretory cells produce at their inner ends a secretion which is poured into the bloodstream.
The Journal of the Quekett Microscopical Club
Authors: Hardwicke Robert
Published: April 2021

When the Quekett Club was originally projected we hailed it as an association of amateur microscopists that would diffuse widely a taste for scientific investigation, and contribute to the great object we had in view in establishing the ‘Quarterly Journal of Microscopical Science.’ It is true that some of the members of the old Microscopical Society looked with a little jealousy at the young club, much as the old Fellows of the Linnean Society in their day regarded the Zoological Club, which terminated in the foundation of the Zoological Society; but in a vast population like London there is, undoubtedly, room for a number of new societies devoted to scientific pursuits. The result has shown that not only has the Quekett Club succeeded, but, so far from doing any injury to the old Society, it has gone on increasing in numbers and influence ever since the establishment of its supposed rival. The truth is, the Quekett Club has been a great feeder of the old Society, and the Members (the Fellows —we beg their pardon) recognised this fact when, at their last meeting, they received with cheers the announcement that the President of the Quekett Club was unanimously elected a Fellow of the Royal Microscopical Society. The President also, with that graciousness which has all along characterised his four years of laborious and useful office, pronounced from the chair his belief that the mother and daughter, after all, had but one common object in their constitution and proceedings. Let us, then, hang down our heads and blush when we think of the hard words and ungenerous feelings which have been exhibited between the two societies.
On Some Organisms Living at Great Depths in the North Atlantic Ocean
Authors: Thomas Huxley F. R. S.
Published: April 2021

In the year 1857, H.M.S. “Cyclops,” under the command of Captain Dayman, was despatched by the Admiralty to ascertain the depth of the sea and the nature of the bottom in that part of the North Atlantic in which it was proposed to lay the telegraph cable, and which is now commonly known as the “Telegraph plateau.”
On the “ Muffa “ of the Sulphur Springs at Valdieri
Authors: Moggridge J.
Published: April 2021

The baths of Valdieri, not far from a Piedmontese town of that name, are situated in a valley on the northern side of the Maritime Alps, and have long been celebrated, not only for the coolness of their climate and the excellence of their mineral waters, but also for the “Muffa,” a sub- stance occurring in one of those waters, which, while of great medicinal value as an external application, is interesting, when viewed under the microscope, for the vegetable, animal, and mineral productions which it contains. These baths are 4426 feet above the level of the sea. Found in those sulphur springs which have a temperature of about fifty degrees Centigrade, the Muffa first appears as tender minute filaments, soft and floating, of a greenish-white colour, surrounded by a mucilaginous milky-white substance imbued with a sulphurous deposit. Of little consistency in its early state, it soon becomes more substantial; changing in colour to violet, then light yellow, and finally to a pale green. When mature, the Muffa resembles a gelatinous lard, carpeting the rock down which the water flows. The vegetable above referred to was considered by Allioni to be Ulva labyrinthiformis of Linnæus. In 1837 Fontan detected a distinct organization, describing it as composed of white filaments from to of a millimetre in diameter; tubular, cylindrical, simple, devoid of septa, containing small semi-opaque globules, collocated when young, and separated towards the ends of the tubes in mature individuals. To this plant he gave the name Sulphuraria, it not having been found in any except sulphur springs. Delponte, of the Botanic Garden at Turin, after careful microscopic examination, places it in the genus Leptothrix (Kützing), near to L. compacta and L. lamellosa, naming it after the place of its nativity, Valderia. A parasitic Ulva accompanies the above, growing upon it, and an Oscillatoria sometimes covers the upper surface, where the water has not more than thirty degrees of temperature. Conferva nigra also occurs.
Memoirs: The Origin and Nature of the Egg Membranes in Chirocephalus Diaphanus
Authors: MAWSON MARY L. , YONGE C. M.
Published: April 2021

1. The anatomy of the female reproductive system in Chirocephalus diaphanus is described with especial reference to the paired anterior and posterior masses of uterine glands.

2. The gland-cells are arranged in pairs surrounded by a common membrane and served by a single duct formed by a separate duct-cell, representing possibly an ingrowth of the uterine epithelium.

3. The glands increase greatly in size during development owing to the formation of a granular secretion which is apparently formed in the nucleus and gradually displaces the original cytoplasm.

4. The egg-case consists of an inner membrane which is chitinous and is formed by the oviducal epithelium, and an outer thicker, rugose membrane which is non-chitinous and is secreted by the uterine glands.

5. Attention is drawn to the close resemblance to conditions in the Decapoda. The inner membrane in both cases is chitinous and formed in the oviduct, while the uterine secretion has much in common with the secretion of the cement glands, but is concerned with protection only and not also with attachment to the body of the female.
Observations on Feeding and Digestion in Glossobalanus minutus.
Authors: Barrington E. J. W.
Published: April 2021

The epidermis and the digestive system of Glossobalanus minutus have been re-examined, and additional information obtained relating to their histology and function, and to the mode of feeding.

The proboscis and collar constitute a simple ciliary mechanism which, aided by the current set up by the pharynx, enables the animal to take in material in suspension in the water or from the surface of the sand. It may thus be considered to retain the primitive ciliary feeding mechanism of the Chordata, although this is obscured in practice by the engulfing of sand associated with the burrowing habit. This retention probably accounts for the fact, recorded by previous workers, that the Enteropneusta frequently protrude their proboscis and collar from their burrows.

The mobile lip of the collar provides a mechanism by which material can be prevented from entering the mouth; large particles can be seen to be rejected in this way.

Suspended material can pass into the dorsal chamber of the pharynx, and collects in small masses which are rotated by ciliary action in the post-branchial chamber before being passed on. This is probably correlated with the fact that the external secretion of the proboscis contains a strong amylase which would pass into the pharynx with the food-material; the two would be mixed in the post-branchial chamber, and further secretions could be added from the latter. The distinction often drawn between a dorsal respiratory chamber and a ventral food chamber in the pharynx is thus not sound, although there is no reason to doubt that the organic content of the sand which passes into the latter can be utilized.

The main cilia of the gill-arches are ‘lateral cilia’; short ‘frontal cilia ‘occur on the secondary arches, but their function could not he observed.

The oesophagus produces a vesicular secretion which is discharged, often accompanied by nuclei, in cytoplasmic spherules.

The epithelium of the ‘liver-sacs’ contain three main types of intracellular inclusion: colourless granular inclusions (believed to be a digestive secretion), brown granular inclusions, and large ovoid bodies with granular contents. The last develop at the distal end of the cells from minute vacuoles ; it is suggested that they may be excretory, although there is no definite evidence for this. All three types of inclusion are discharged from the cells, sometimes with nuclei.

The intestinal epithelium is concerned with secretion, but to a much less extent than the sacs. The ovoid bodies and the brown inclusions are only produced in the latter.

Evidence for the digestion of starch, glycogen, maltose, sucrose, casein, and triacetin is provided ; raffinose and inulin are not digested. Indications of the pH range of the amylase, protease, and lipase are given.
Development of the Dermal Bones in the Skull of Lepidosteus osseus
Authors: Aumonier F. J.
Published: April 2021

1. The development of the dermal elements of the skull of Lepidosteus osseus has been studied in a series of twelve stages.

2. The homologies of the three small scale-bones of the snout have been established. They are the rostral, nasals, and antorbitals.

3. The ‘maxillary chain’ is shown to be an extension of the infra-orbital series, and the existence of a true maxillary is established.

4. The extent and single origin of the premaxillary are shown, and its unusual association with the supra-orbital basal is discussed.

5. The correct homologies of the opercular series have been established, the recognition of a sub-orbital has been recorded.

6. It is shown that Stensiö’s complex nomenclature is redundant to a description of the dermal bones of the skull of Lepidosteus osseus.
On the Identity of the White Corpuscles of the Blood with the Salivary, Pus, and Mucous Corpuscles.
Authors: G. Richardson Joseph
Published: April 2021

The nature of the nucleated corpuscles so abundant in the saliva has long been a subject of some uncertainty, and although they have probably, as favorite test objects for the higher powers, been more frequently examined by microscopists than almost any other constituent of the glandular secretions, observers seem to have been generally contented to accept them simply as useful measures for the capacity of the higher objectives, and passed on without any attempts to solve the mystery of their origin ; Kölliker, indeed, advanced the theory that they were essentially a form of exudationcorpuscles, but hitherto his hypothesis does not appear to have been generally accepted by microscopists as a fixed fact.
Notes on the Thysanura.
Authors: Lubbock John
Published: April 2021

Sir John began by adding four more species to the list of British Thysanura, which now comprises about fifty species, of which only fourteen were recorded as British when he began to study the group. Three out of the four now added are Continental species ; the fourth does not agree with any as yet described. He then made some remarks on the reproduction of lost parts, especially on the reparation of wounded antennæ. He showed that if an antenna is cut off, for example, in the middle, it never again recovers the normal number of segments, and he mentions the curious fact that among the species with longest antennæ it is extremely rare to find a full-grown specimen in which these organs are perfect. It is also remarkable that the reproduced segments acquire an abnormal length. Thus, for instance, if a Tomocèrus has the terminal and part of the third segment removed, the terminal segment is never reproduced, though the penultimate one acquires a greater length than in un- mutilated specimens.
Note on a New Means of Examining Blood Under the Microscope, Andon the Blood-Fluids of Invertebrates, and on a Natural Standard for Registering Absorption Spectra.
Authors: Ray Lankester E.
Published: April 2021

My friend, Dr. Arthur Gamgee, last year suggested to me that I should try the new blood-matter, Chlorocruorin, which I discovered in Siphonostoma and Sabella two years since (see Humphry’s and Turner’s ‘Journal of Anatomy,’Nov., 1867) with Day’s guaiacum-and-peroxide-of-hydrogen-test (see ‘Quart. Journ. Mic. Sci.,’ 1868, p. 282). This I accordingly did, and obtained the most satisfactory results, the guaiacum being rendered brilliantly blue in the usual way by the Chlorocruorin and ozonic ether. I also proceeded to try a great number of blood-fluids of Invertehrata. In all cases where the presence of Hæmoglobin (Cruorin) had been proved by me with the spectroscope to be present I did not fail to obtain the blueing of the guaiacum, e. g., in Planorbis, in larva of Chironomus and allied larvæ, and many Annelids. The colourless fluids among these groups I also tested with the guaiacum and “ozonized ether,” having been led to suspect that in the colourless blood of insects, molluscs, &c., there must be a body having properties similar to those of Hæmoglobin and Chlorocruorin. The perivisceral fluid of Annelids gave the blue colour with guaiacum, the colourless blood of some insects, Crustacea, and molluscs also. In many there was simply an evolution of gas on the addition of the ozonized ether, and no blueing of the guaiacum. I attribute this to the fact that the action was less energetic in these cases than in the case of the red Hæmoglobin or cruorin, which acts far more powerfully with the test than anything else, excepting Chlorocruorin. The mere evolution of the gas is, however, a good test, and can be applied beneath the microscope. Thus, I have been able to bring ozonized ether into contact with very small Entomostraca, and even with some Infusoria, on the microscope-stage, and observe from what part especially the development of gas takes place. The blood-corpuscles may in this way be demonstrated as being the part of vertebrate blood from which oxygen is eliminated in the guaiacum experiment.
The Morphology of the Gut of the Brown Trout (Salmo trutta)
Authors: Burnstock G.
Published: April 2021

In the trout gut a short oesophagus containing only striated circular muscles opens into a large cardiac stomach possessing inner circular and outer longitudinal smooth muscle-coats, as well as a muscularis mucosae. About 45 pyloric caeca come off the intestine, which, while containing muscle-coats, does not possess a muscularis mucosae. In the rectum, the longitudinal muscle is as thick as the circular muscle-coat, but in other regions the circular muscle is dominant, especially in the pyloric stomach where it is over 10 times as thick as the longitudinal layer. The mucosa is distinguished by the presence of a prominent layer of dense collagen, the stratum compactum, which is perforated only by nerves and blood-vessels. This layer forms a firm and relatively inextensible (approximately 10% extensibility) basis to the gut-wall. It limits the extensibility of the smooth muscle to 75 % radially in the stomach and 25% radially and longitudinally in the intestine. In contrast, the stomachs of the pike and perch, which do not possess a stratum compactum, extend up to 200%. A detailed description of the regional junctions and sphincters gives a basis for the interpretation of events occurring in the living system. Valves at the junction of the pneumatic duct with the oesophagus, and between the duodenum and pyloric stomach, serve to prevent the regurgitation of gas and semi-digested food respectively. A complex sphincter mechanism exists at the pylorus, and to a lesser extent at the antrum. A series of about five circular muscle-constrictors represents the anus. It is suggested that the cells forming the stratum granulosum, a layer closely associated with the stratum compactum, are composed of active fibroblast cells producing collagen. The rectum contains a muscular annulo-spiral septum of unknown function which protrudes into the lumen.
A Histological and Histochemical Study of the Brown and Yellow Adipose Tissue of the Bat, Hipposideros speoris
Authors: George J. C. , Eapen J.
Published: April 2021

A study of the histology and histochemical reactions for lipase, alkaline phosphatase, acid phosphatase, adenosine triphosphatase, succinic dehydrogenase, lactic dehydrogenase, phospholipids, cholesterol, sulphydryl groups, and water-insoluble aldehydes and ketones in the brown and yellow adipose tissue of the bat (Hipposideros speoris) revealed that the two types of adipose tissue differ in histological structure as well as physiological activity. The histological structure of the two types of adipose tissue was found to be different, resembling that of the two corresponding types of the rat. The brown adipose tissue showed a higher concentration of succinic dehydrogenase, lactic dehydrogenase, phospholipids, cholesterol, and sulphydryl groups. No detectable difference between brown and yellow adipose tissue was, however, found with respect to lipase, alkaline phosphatase, acid phosphatase, adenosine triphosphatase, and waterinsoluble aldehydes and ketones.
The Ontogeny and Comparative Anatomy of some Protocerebral Sense Organs in Notostracan Phyllopods
Authors: Dahl Erik
Published: April 2021

An investigation of the ontogeny of some of the protocerebral sense organs of Triops was carried out. Attention is called to the presence of a frontal proliferation zone of great importance in the growth of the nauplius and compound eyes. With respect to the nauplius eyes it is shown that to the small tripartite nauplius eye present at hatching additions are contributed partly by the dorso-lateral lobes of the brain, partly by the proliferation zone. This complicated mode of derivation of the nauplius eye is reflected in the arrangement of the nerves. The so-called upper lateral nauplius eye nerve in Triops is shown to be the remnant of the connexion between the nauplius eye and the ganglion opticum of the compound eye, and the evidence suggests that it is not really to be regarded as an optic nerve of the nauplius eye. It is shown that the proliferation zone is mainly or exclusively responsible for the formation not only of the distal part of the compound eye but also of the ganglion layer of the lamina ganglionaris and of the distal part of the ganglion layer of the medulla. The dorsal paired frontal organs as described by Claus (1873)are identified with a group of sensory cells situated above the lateral nauplius eye in the adults of Triops, and the ontogenetical processes involved in their dislocation are traced. The group of cells in the neighbourhood of the ganglion opticum supposed by Wenke (1908) and Hanstrôm (1931) to be identical with the frontal organs found by Claus (1873) probably constitute a neurosecretory organ. It is shown that despite great topographical differences the ontogeny of the protocerebral sense organs of Artemia in many respects follows the same pattern as in Triops.
The Botryoidal and Vaso-fibrous Tissue of the Leech Hirudo medicinalis
Authors: Bradbury S.
Published: April 2021

The botryoidal and vaso-fibrous tissues of the leech Hirudo medicinalis have been studied morphologically and histochemically. It is concluded that the cells forming these tissues represent cells of the vessel and sinus walls which have swollen as a consequence of the accumulation of pigment granules in their cytoplasm. This swelling is much more pronounced in the cells of the botryoidal tissue. These tissue systems are in communication with each other and with the contractile and non-contractile haemolymph vessels.

Apart from the pigment granules, few cytoplasmic inclusions were seen in the cells of the botryoidal tissue, but numerous granules are present in the vaso-fibrous cells : these granules are about I µ in diameter and contain phospholipid. The brown pigment of the botryoidal tissue seems to consist of a masked iron compound, which probably occurs in combination with the protein which forms the framework of the pigment granule; the pigment of the vaso-fibrous tissue is green, and contains no iron, but reacts to the tests for bile pigments.

These tissues are considered to represent ‘kidneys of accumulation’ for the iron and the bile pigment which probably represent the by-products of a breakdown of the blood used as food. The amount of botryoidal tissue is significantly greater in old than in young leeches.
Contractility and Hydroplasmic Movements in the Hydroid Clytia johnstoni
Authors: Hale L. J.
Published: April 2021

The investigation is based on observations of the living animal and on time-lapse films, and is supplemented by histological preparations. The material was cultured in the laboratory.

A short region just behind the growing tip of a stolon is contractile, pulsating every 4 or 5 min but occasionally at longer intervals. This causes the hydroplasm (contents of coelenteron) to ebb and flow in the coelenteron not only directly, but also by pressure transmitted by the fluid between the coenosarc and perisarc. There is evidence that where a stolon has more than one contractile region, they beat independently. The contractile cells do not possess muscle-tails, and contractile fibres have not been detected by light microscopy.

The hydranth stomach also has slow contractions which are peristaltic towards the stalk. They usually occur at irregular intervals but are occasionally regular. They cause movement of the hydroplasm into and out of the hydranth. There is evidence that hydranths are stimulated to expand and contract by arrival of hydroplasm pressed there by another contractile region of the colony. Longitudinal muscle-tails are present on the ectoderm cells of the stomach and tentacles, but these are probably concerned with retraction of the hydranth into its hydrotheca.

Although the endodermal flagella beat actively when the hydroplasm is in motion, they are not the cause of hydroplasmic flow.

The possible mechanism of these slow contractions is discussed in relation to contractility in other coelenterates.
Differences in the Blood-supply of Bone of Different Histological Types
Authors: Currey J. D.
Published: April 2021

‘Laminar’ bone, commonly found in artiodactyls and dinosaurs, is described. It consists of a series of bony laminae arranged like tree-rings round the marrow cavity, each lamina being between o-i and o-2 mm thick. Sandwiched between each lamina and the next is an effectively two-dimensional network of blood-vessels. Laminar bone grows in a series of spurts ; a sheet of woven-fibred bone is formed very quickly, not actually on the pre-existing sub-periosteal surface, but separated from it by a space. The new bone is held clear of the original surface by an occasional bridge of bone. The space so formed is filled in slowly by parallel-fibred lamellar bone, and while this is going on more woven bone, with spaces, may be formed by the periosteum.

The vascularization of laminar bone on the one hand and bone composed of haversian systems on the other is compared, chiefly in cattle. Laminar bone has a more intimate blood-supply than haversian bone, and it has a larger surface area of bloodchannel per unit volume. The volume of channel per unit volume is about equal in the two types of bone. The mean distance between anastomoses is less in laminar than in haversian bone. The cement-line round haversian systems hinders the passage of materials through the canaliculi. The osteocytes in the interstitial lamellae are thus in a worse position for obtaining foodstuffs and disposing of waste products than osteocytes in laminar bone a similar distance from the nearest blood-vessel.

It is suggested that the formation of haversian systems in laminar bone interferes with the latter’s blood-supply and leads to the formation of further haversian systems.
A Note on the Innervation of the Integument in Amphioxus, and its Bearing on the Mechanism of Cutaneous Sensibility
Authors: Bone Quentin
Published: April 2021

Previous conclusions as to the innervation of the integument of amphioxus are discussed, and it is shown that in addition to the system of free nerve-terminals described by Lele, Palmer, and Weddell (1958), the skin of certain regions of the body contains specialized sensory cells and encapsulated nerve-endings. The cells of origin of the free nerve-terminals in the skin are described, and it is shown that they fall into several morphologically different categories. In the light of these observations it is suggested that the innervation of the skin of amphioxus does not provide unequivocal evidence for the view that the different cutaneous sensations are determined by different discharge patterns in the same fibres of the nerve-rami leading from the skin.
The fine structure of the normal chorio-allantoic membrane of the chick-embryo
Authors: Rangan S. R. S. , Sirsat Satyavati M.
Published: April 2021

The chorio-allantoic membranes of White Leghorn chick embryos at 10 to 12 days after laying were fixed in Palade’s buffered osmium tetroxide or in Luft’s potassium permanganate.

After fixation in these two ways the general appearance is similar, but there are differences in certain tissue elements. Cell membranes are well preserved after fixation in KMnO4. Certain lipid inclusions in the cytoplasm of the cells of the allantoic layer are well seen after fixation by OsO4, but not after KMnO4; in their places empty vacuoles are seen.

Details of the structure of the red blood-corpuscles are more clearly seen after fixation in KMnO4.
Naked axons and symmetrical synapses in coelenterates
Authors: Horridge G. A. , Mackay Bruce
Published: April 2021

Examination of sections of the marginal ganglion of the jellyfish Cyanea and the hydromedusan Phialidium by the electron microscope, in a region where nervous tissue is readily identified on account of its abundance, reveals the following features.

Nerve-cell bodies and axons are crowded together without special glial cells. The axons form a layer between the cell-bodies and the mesogloea and the spaces between them are continuous with other intercellular spaces and with the mesogloea.

Features typical of nerve-cells in other animals are mitochondria, Golgi region (= γ-cytomembranes), neurotubules (= canaliculi) about 16 mμ wide, and several types of vesicle ranging in size from 50 to 200 mμ, including synaptic vesicles of 50 to 100 mμ.

Features not typical of nerve-cells are the modified (possibly sensory) cilia on the dendrites of bipolar cells and the absence of clumps of Nissl substance and neurofilaments.

Synapses between axons (or with a perikaryon) have a synaptic cleft of 18 to 22 mμ and a crowded row of synaptic vesicles within the neurones on each side of the synapse.
Studies of an amoebo-flagellate, Naegleria grüberi
Authors: Pittam M. D.
Published: April 2021

The amoeboid and flagellate phases of Naegleria grüberi were examined by phase- contrast microscopy, cytochemical techniques, and conventional staining methods. Some electron micrographs were taken. Results showed that lipid was confined to the cytoplasmic globules, cell membrane, and mitochondria. Glycogen was absent, but a polysaccharide, probably a protein-carbohydrate complex, was generally distributed throughout the cytoplasm and was particularly abundant in the food vacuoles. Particular attention was paid to the mitotic figure, with the result that stage I of mitosis, in which RNA-protein and DNA-protein particles were dispersed throughout the nuclear area, is claimed as being a constant and essential occurrence in the initia- tion of mitosis. After stage I, the RNA and DNA took up and remained in sharply demarcated areas of the mitotic figure. No lipid or carbohydrate was present in the mitotic figure.

During the transformation from amoeba to flagellate, some of the mitochondria concentrated at the point on the periphery of the organism where the flagella later emerged, and in the fully formed flagellate appeared as a dense cap at the bases of the flagella. Electron micrographs showed that the mitochondria had a double limiting membrane and an internal system of tubules similar to those described in Acanth- amoeba.
A counting method for measuring the volumes of tissue components in microscopical sections
Authors: Douglas Hally A.
Published: April 2021

Several methods are available for estimating the relative volume of a tissue component from a study of tissue sections. These methods are all based on the fact that the mean relative area of a component in a series of random sections through a tissue is a consistent estimate of its relative volume in the whole tissue. Thus the problem is basically one of measuring area in a section, which can be done by the following simple counting method.

The method consists of placing a regular pattern of points in the form of a square lattice upon the section image, and counting the number of points over the section TV, and over the component n. The method also measures absolute area, and where d is the distance between adjacent points, This capacity to measure absolute area means that the method is particularly suitable for determining a component which has a low relative volume.

The accuracy of the method is influenced by several factors including the size of the grid mesh, and the relative area, shape, and spatial arrangement of the component. With reasonable care the error will not be larger than that of a truly random system of points, as expressed by the following: wherep is the relative area of the component, and the relative standard error (R.S.E.) is S.E./relative area of component.

The method is equally applicable to either light or electron microscopy. A series of measurements on electron micrographs of rat cardiac muscle revealed a close agreement between the counting method and planimetry.

The method is rapid, simple and accurate, and requires no complex apparatus.
The innervation of the aesthetasc hairs of Panulirus argus
Authors: Laverack M. S. , Ardill D. J.
Published: April 2021

The aesthetasc hairs that occur on the outer ramus of the antennule of Panulirus argus are heavily innervated. Approximately 350 neurones are present at the base of each hair, and dendrites pass up into the hair lumen.

These dendrites end one-third of the distance to the hair tip. They are composed of paraciliary structures that extend beyond the surrounding sheath. The hair lumen is in contact with the external environment through a pore at the end of the hair.

The sensory cells are surrounded by sheath cells along the axons and as far distally as the sensory cell nucleus. Distally the dendrites are also sheathed by glia and hypodermal cells. The distal region of the sense cell body is not invested, the cell membranes are closely applied one to another and interdigitation occurs.
Electron Microscope observations on Mitotic Chromosomes
Authors: BARNICOT N. A. , HUXLEY H. E.
Published: April 2021

A method is described by which single mitotic cells growing in tissue culture can be selected under the light microscope and then sectioned for electron-microscopic study. The method has been applied to mitotic cells in newt heart cultures and to monolayer cultures of human fibroblasts. The structure of the chromosomes and of the mitotic apparatus at various phases of mitosis are described and discussed. The effects of pH and of divalent cations on the fixation of chromosomes by buffered osmic mixtures are also considered.