bluuebunny/crossref_metadata_2025 huggingface dataset:
The Peri-renal Tissue of Protopterus A Contribution to the History of the Adrenal
Authors: Holmes W. , Moorhouse D. E.
Published: April 2021

The animal studied, was the lungfish Protopterus aethiopicus; the investigation was histological and cytochemical, the material being freshly taken from East African lakes.

The peri-renal tissue is a substantial organ which, because it surrounds the kidney, extends through the greater part of the body cavity. Those who have investigated its structure in recent years have considered it to be a haematopoietic organ.

A wide variety of histological, histochemical, and haematological techniques was used. The organ is shown to contain five characteristic kinds of tissue; these are named: lipid, endothelial, pigmented, round-cell, and steroid tissue respectively.

The lipid tissue is characterized by cytoplasmic liposomes—droplets containing phospholipid. In one type of cell, the ‘small lipid cell’, which may be related to the eosinophil granulocytes of the blood, the droplets have a relatively small diameter. In a second type, the ‘large lipid cell’, the droplets grow to a much larger diameter, and show evidence of cycles of activity involving increase and disappearance of the phospholipid. Histochemical interpretations are made difficult by the finding that this phospholipid does not colour with Sudan black.

The endothelial tissue is composed of phagocytic (macrophage) cells some of which are elongated and line vascular sinusoids while others are spherical and contain larger inclusions. These inclusions have some lipid characteristics and may be a manifestation of the translocation of lipid within the organ.

The pigmented tissue is composed of melanophores and of a second, round, type of cell which shows evidence of relationship with the macrophage system. Both kinds of cell contain ‘melanin’; the second also has inclusions with different histochemical properties.

The round-cell tissue, found in nodules, has a general resemblance to lymphoid tissue. It is doubtful whether its cells are lymphocytes, but it has not been found possible to characterize them in any other way.

The steroid tissue is composed of cells which react positively to the histochemical tests comprised in the ‘steroid repertoire’, as used in the study of the mammalian adrenal.

Attention is drawn to technical difficulties which may have confused the study of the peri-renal tissue as a haematopoietic organ. The connexion between the lipid tissue and circulating granulocytes has features which distinguish it from the processes of granulocyte formation in the spleen.

There are strong indications of an evolutionary connexion between peri-renal tissue and the cortex of the adrenal gland of higher animals. The lungfish may offer the best starting-point for the study of the comparative histology of the adrenal of tetrapods. The association between lipid, steroid, haematopoietic, macrophage, and pigment tissue has parallels in function in the complex interrelations of the mammalian adrenal.
The Structure of the Corpus Allatum of Iphita limbata (Hemiptera)
Authors: Nayar K. K.
Published: April 2021

The corpus allatum of Iphita limbata Stal. (Pyrrhocoridae, Hemiptera) is an unpaired, syncytial gland, with nuclei of two sizes. The allatic nerve transmits neurosecretory colloids into the gland. The recurrent nerve adjacent to the allatic nerve also contains neurosecretory products. The cytoplasm of the gland contains granular mitochondria which show a tendency to aggregate into clusters or rings and chains, and numerous tiny spheroids of variable size forming the lipochondria, which are sudano-phil, argentophil, and generally osmiophil. Vacuoles are present in the cytoplasm; these are surrounded by spheroids. The cytoplasmic content is rich in phospholipids. The gland is larger in the female. It gradually enlarges as the eggs develop and reaches its maximum size in the gravid female.
Further Observations on the Histochemistry of Fat Absorption in the Small Intestine of the Rat
Authors: Hewitt W.
Published: April 2021

Studies have been made of the small intestine of rats previously fed with triolein. A previous description of the location of the lipid and phospholipid has been confirmed by using Sudan black and the acid haematein test. In addition histochemical tests have been applied to detect neutral fat and fatty acid. The lipid in the free border of the epithelial cells of the mucous membrane consisted of fatty acid and probably neutral fat, which would support the belief that when neutral fat is absorbed some of it is unhydrolysed. Additional evidence for this is provided by the fact that neutral fat could also be detected between the lateral parts of the cells. Occasionally fatty acid was also detectable in this location. Variable proportions of neutral fat, fatty acid, and phospholipid were to be found inside the epithelial cells and it appeared possible that there was a direct relationship between the amounts of neutral fat and phospholipid present.
Normal and Induced Degeneration of Abdominal Muscles during Metamorphosis in the Lepidoptera
Authors: Finlayson L. H.
Published: April 2021

Certain segmental units of the three main longitudinal muscle-bands in the abdomen of the larva of Galleria, Platysamia, Telea, Antheraea, and Samia (Philosamia) do not degenerate during the histolytic phase in the prepupa and early pupa. In the 3rd abdominal segment the amount of muscle that persists is variable; in the 4th, 5th, and 6th segments, invariable. Apart from single pairs of transverse muscles in the 2nd and 3rd segments and those of the gut and heart there are no other muscles in the pupa. Vestiges of degenerated muscles are often found in the pupa.

The longitudinal muscles which survive the transformation of the pupa into the adult degenerate during the first z days of adult life.

Experiments were made on larvae, prepupae, pupae, and adults in attempts to influence muscle-degeneration and muscle-persistence. Extirpation of ganglia or severance of nerves in larvae and prepupae of Galleria caused the normally persistent muscles to degenerate during pupation. Controls in which larvae were dissected before pupation revealed no degeneration of denervated muscles. In saturniids denervation also resulted in degeneration or atrophy but only after a much longer period, a matter of several weeks instead of several days. Muscles may be affected by extirpation of ganglia or severance of nerves in segments preceding their own segment.

Previous workers have shown that the growth of the new adult muscles is dependent on the influence of the central nervous system. This is not so in the case of sheets of fine muscle-fibres lying under the epidermis of the adult. They develop in the absence of central innervation.

Operations which had no effect on muscle-degeneration in the adult included extirpation of ganglia in pupa and adult, beheading and bleeding, extirpation of corpora allata plus corpora cardiaca, ligations, extirpation of pupal gonads, and isolation of adult abdomens. Substitution of blood from diapausing pupae or saline for the adult blood in isolated abdomens was effective in slowing the process of muscle-degeneration. This result shows that the blood composition is of importance in the process of histolysis in the adult.

The previous work on the physiology of insect histolysis is briefly reviewed. The influence of the nervous system as described in this paper is discussed and related to similar findings in other arthropods and in vertebrates.
The Blood Vascular System of Nephtys (Annelida, Poly chaeta)
Authors: Clark R. B.
Published: April 2021

The four longitudinal vessels of the circulatory system of Nephtys califomiensis are dorsal, sub-intestinal, and neural, the latter being paired. There is a complete longitudinal circulation; the dorsal vessel communicates with the sub-intestinal by way of the proboscidial circulation and with the neural by way of the circum-oral vessels. In each middle and posterior segment segmental vessels from each of the longitudinal trunks carry blood to and from the parapodia and body-wall. The segmental circulation is completed by a circum-intestinal vessel connecting the dorsal and sub-intestinal vessels in each segment and an intersegmental branch connecting the dorsal and sub-intestinal segmental vessels. A trans-septal branch of the neural segmental vessel communicates with the sub-intestinal segmental vessel. This arrangement is modified in anterior segments which house the muscular, eversible pharynx, and no blood-vessels cross the coelom except by running through the body-wall. On anatomical grounds and by comparison with other polychaetes it seems likely that segmental is subordinate to longitudinal circulation. There are no endothelial capillaries such as have been described in some other polychaetes; instead there are numerous blindending vessels the walls of which are composed of the same three layers as other vessels and which are probably contractile. The dorsal vessel, where it is in contact with the ventral surface of the supra-oesophageal ganglion, forms a plexus in close association with a modified part of the brain capsule and a special axonal tract within the ganglion. It is thought that by way of this ‘cerebro-vascular complex’, hormones produced in the neurosecretory cells of the brain pass into the blood-stream.
A simple apparatus for freezing-drying histological specimens
Authors: Kramer H. , Hill R. G.
Published: April 2021

The construction and operation of a simple apparatus for freezing-drying histological specimens is described. The apparatus, which is constructed from materials readily available in most laboratories, requires neither elaborate pumping equipment nor vapour traps, for the water molecules emanating from the specimens are carried away by a stream of dry gas. By this means specimens can be dried from a lower temperature in a time considerably shorter than is possible with the more complicated and costly freezing-drying apparatus usually used.
The Antennal Pulsating Organs of Mosquitoes and other Diptera
Authors: Clements A. N.
Published: April 2021

The antennal pulsating organ of mosquitoes consists of two vesicles, each sending a blood-vessel to the antenna of its side and each connected to the aorta by a muscle. Contraction of the muscle causes blood to enter the vesicle through a valve and relaxation allows an elastic contraction of the vesicle so that the blood is discharged through the blood-vessel to the antenna. The organ appears to be myogenic.

Antennal pulsating organs occur in most families of the Diptera Nematocera but not all, and a similar organ is present in Drosophila.
Observations on the stomach and digestive diverticula of the lamellibranchia: II. The nuculidae
Authors: Owen G.
Published: April 2021

The anatomy and histology of the stomach and digestive diverticula and the physiology of digestion in the Nuculidae have been investigated.

The stomach is relatively large and possesses a well-developed style sac, although a rod-like crystalline style is absent. Sorting areas are present in the dorsal region of the stomach but the ciliary currents are relatively weak and have little effect on the ingested material.

The digestive diverticula consist of three regions, the physiological relations of which have not been fully elucidated. The three regions are: (a) a much-branched system of non-ciliated main ducts, the epithelium of which shows a well-developed brush-border; (b) short, unbranched ciliated secondary ducts; (c) irregularly branched blindly ending tubules. The epithelium of the tubules is divided into two regions, one composed of large cells containing numerous conspicuous granules and the other of less frequent and smaller darkly staining cells. Each darkly staining cell bears a single flagellum.

Separate mucous glands cannot be demonstrated in any part of the stomach or digestive diverticula.

The epithelium of the style sac secretes an amylase and a lipase. Extracts of the digestive diverticula contain an amylase, a lipase, and a protease.

Unlike the majority of lamellibranchs, fluid and solid particles do not appear to enter the digestive diverticula from the stomach and in no part of the gut or of the diverticula is there ever any evidence of intracellular digestion. It is suggested that in the Nuculidae digestion is exclusively extra-cellular and confined to the stomach. The soluble products are absorbed by the epithelium of the stomach and first part of the intestine.

The diverticula of the rest of the Lamellibranchia are compared with those of the Nuculidae. While the Nuculidae are in many respects primitive lamellibranchs, the conclusion is reached that the digestive diverticula present many specialized features possibly correlated with the method of feeding.
A Method for High-power Stereoscopic Microscopy
Authors: Galbraith W.
Published: April 2021

An expanded account is given of a simple modification to an ordinary beamsplitting microscope, which renders it stereoscopic. The full aperture of the objective is used, so the method is applicable to all powers of the microscope. The method involves dividing the lower focal plane of the condenser into left and right halves with opposite polarization by means of Polaroid, and isolating the two resulting beams in the eyepieces with Polaroid analysers.

This system, first published by Jackson (1944−9), gives excellent results with the highest powers of the microscope, but appears to have been forgotten. This paper is written in the hope of re-introducing it.
The Interference Microscope as Refractometer for Liquids
Authors: Iversen S. , Smith F. H.
Published: April 2021

Determination of the refractive index of liquids by the interference microscope was made possible by the use of a specially constructed holder for the liquid. This ensures a permanent lateral separation between the reference and the object areas and, as the depth of the object area is continuously increasing, a system of fringes is observed. The spacing of the fringes is a function of the refractive index of the liquid. By determining this spacing, a measurement of the refractive index is obtained. An accuracy of at least 0-0001 in refractive index is obtainable by a single measurement.
Mauthner Neurones in Young Larval Lampreys (Lampetra spp.)
Authors: Whiting H. P.
Published: April 2021

‘Mauthner’s cells’ are a pair of very large neurones found in the hind-brain in all main groups of fishes and amphibia, except in sharks and rays. Mauthner cells always have some dendrites in synaptic relation with incoming VUIth-nerve fibres and have a large axon which crosses the brain and descends the opposite side of the spinal cord, co-ordinating somatic motor activity. Papers discussing the presence of these cells in the lampreys are reviewed: two different pairs in the lamprey of ‘Miiller’s cells’ (giant co-ordinating cells with homolateral axons) have been considered homologous with Mauthner cells, but recent textbooks accept neither homology.

A pair of very large neurones, having the Mauthnerian characteristics, is described in the embryonic and early larval stages of Lampetra planeri and L. fluviatilis. The neurones are illustrated by figures in different planes. They are not one of the pairs of Millier neurones described by previous workers.

From this and similar evidence it is suggested that in all non-amniote vertebrates the earliest swimming movements under the control of the brain are effected through variations from one homologous co-ordinating system, of which the Mauthner cells form part.
The Formation of the Secretory Granules in the Liver-cells of the Slug, Anadenus altivagus
Authors: Rishi Rajinder
Published: April 2021

The process of formation of secretory granules has been studied in the liver-cells of the slug, Anadenus altivagus, in fixed preparations. The following conclusions have been drawn.

The secretory granules, which are non-lipid in nature, are formed by direct transformation of the lipid granules. The lipid granules assume a duplex structure during this transformation.

The lipid granules, which are densely packed at the basal end of the cells, seem to arise from the tip-granules of the mitochondria.

The mitochondria are fibrillar and each of them shows one prominent granule at each tip. The mitochondria as well as their tip-granules are stainable with iron haematoxylin after Regaud, whereas the lipid granules are not.
The Cytoplasmic Inclusions of the Neurones of Patella vulgata
Authors: Chou John T. Y.
Published: April 2021

The cytoplasmic inclusions of the neurones of Patella vulgata have been studied by Lacy and Rogers (1956) and Lacy and Horne (1956). These authors studied thin sections under the electron microscope and made ‘Golgi’ preparations by Kolatchev’s technique; they also examined living cells dyed with neutral red. It appeared to me desirable to check and extend their observations in several ways. I decided to undertake a much fuller study of the living cell by phase-contrast microscopy and the use of a wide range of vital dyes. It was also necessary to determine the composition of the cyto-plasmic inclusions by cytochemical tests.
A Histochemical Study of the Pigment Cells of the Leech, Glossiphonia complanata
Authors: Bradbury S.
Published: April 2021

Glossiphonia complanata was found to contain two types of pigment cell. One is very large, usually globular in section, and is found in the deeper layers of connective tissue near the intestinal caeca. The second type is smaller and occurs only in the subcutaneous region of the body.

The large pigment cell contains very many, regular, pigmented spheres, each of which is about 3 p in diameter. These spheres have a proteinaceous substrate which is partly composed of tyrosine, arginine, and perhaps some histidine. Histochemical and other tests indicate that the yellowish pigment contained in the spheres is amost certainly a tetra-pyrrol compound, possibly related to the vertebrate bile pigments. The pigmented spheres may contain ‘masked’ iron. It is suggested that these pigmented spheres represent the accumulated waste products of haemoglobin breakdown, and so constitute a ‘kidney of accumulation’.

The subcutaneous pigment cell is typically stellate. Both the cell-body and its numerous branching processes are filled with small brown pigment granules which never exceed i/z in diameter. This pigment is characterized by extreme insolubility and chemical inertness, suggesting that it is a melanin. It is these cells which are primarily responsible for the colour of the animal.
A cytological and histochemical study of the connective- tissue fibres of the leech, hirudo medicinalis
Authors: Bradbury S.
Published: April 2021

The presence of fibres in the connective tissue of leeches has been noted by many authors since Ray Lankester (1880) first figured them in his paper on the histology of Hirudo medicinalis. Bourne (1884) and Scriban and Autrum (1934) in particular deal with their general structure, but as far as is known, no detailed histochemical study has been carried out on the fibres of this species of leech. Recently an account was published (Bradbury, 1957) describing the histochemistry of similar fibres which occur in the rhynchob-dellid leech, Glossiphonia complanata, together with details of the ground-substance in which they are embedded. It is the purpose of this paper to give a comparable account of the fibres, fibrocytes, and intercellular matrix in the gnathobdellid leech H. medicinalis.
A Study of Fibrogenesis in the Leech, Hirudo medicinalis
Authors: Bradbury S. , Meek G. A.
Published: April 2021

Although the existence of fibres in the connective tissues of leeches 21.has been known for a long time, little work has been published on them in the last twenty years. Recently these fibres have been studied structurally and histochemically in the leeches Glossiphonia complanata and Hirudo medicinalis (Bradbury, 1957, 1958).
Observations on the Mantle of the Lamellibranchia
Authors: Beedham G. E.
Published: April 2021

The variation in histology between the epithelial regions of the mantle in Anodonta cygnea concerned with the secretion of the different layers of the shell has been investigated. The epithelia on the outer surface of the outer mantle fold which secrete the outer layer of the ligament and the corresponding outer calcareous layer of the valves are basically alike in structure. They are also comparable in appearance with the epithelium on the inner surface of the outer mantle fold which secretes the perio- stracum and with that of the fused outer folds responsible for the formation of the fusion layer of the ligament. All these epithelial regions can readily be distinguished histologically from the epithelia of the general outer mantle surface and of the mantle isthmus which produce the inner layers of the valves and ligament respectively.

The histological differentiation of the mantle epithelium in Anodonta is compared with that of Mytilus edulis and Ostrea edulis. The degree of zonation of the epithelium can be correlated with the extent to which the shell layers differ in composition from one another. It is suggested that the variation in histological appearance between epithelia from different areas of the mantle is partly determined by the relative amounts of non-calcareous material (conchiolin) which these epithelia produce and by the rate of their secretory activity.

The different epithelial regions of the mantle in Anodonta and other lamellibranchs vary appreciably in their reactions to histochemical tests for alkaline phosphatase, ribonucleic acids, and glycogen. In Anodonta, the epithelial cells of the outer mantle fold differ markedly from those which secrete the inner layers of the shell in that they exhibit high alkaline phosphatase activity and appear to be rich in cytoplasmic ribonucleic acids. In contrast, the epithelium of the general outer surface of the mantle is distinguished by a high content of glycogen, a condition which also occurs in many other bivalves. It is interesting to note that alkaline phosphatase can be demonstrated in epithelia which secrete non-calcareous regions of the shell. In all the lamellibranchs investigated, ribonucleic acids can be detected in relatively higher concentration in epithelial cells concerned principally with the secretion of conchiolin.
The Gross Morphology of the Anterior Nervous System of Nephtys
Authors: Clark R. B.
Published: April 2021

The supra-oesophageal ganglion of Nephtys varies considerably in its size and gross morphology from one species to another. The ganglion is relatively larger in small species and then extends into the anterior body segments. It is epidermal and in contact with the cuticle in the prostomium, sub-epidermal in the anterior segments. In a number of species a pair of conspicuous posterior lobes to the ganglion has been developed. There is a tendency, particularly in the smaller worms, for the ganglion to be bifurcated at its posterior, and sometimes also at its anterior margin. The sensory nerves are as follows : tegumentary nerves, extremely variable in number and disposition, arising from the front of the ganglion; two pairs of antennary nerves arising immediately above the roots of the circum-oesophageal connectives, but generally distinct from them; and a pair of anterior optic ‘nerves’ supplying the paired, single-celled photoreceptors. The only other nerves arising from the ganglion are the nuchal nerves which arise from it opposite the nuchal organs, whatever the position of the brain. Since the latter may barely protrude into the prostomium, these nerves emerge from the anterior part of the brain in some species, instead of near the posterior end of the ganglion. The circum-oesophageal connectives are extremely long because the sub-oesophageal ganglion lies in the fifth segment. In their passage through the lateral lips of the mouth and along the sides of the guiar membrane, they give off three pairs of stomatogastric nerves and the segmental nerves of the first two segments. The third and fourth segmental nerves arise from the front of the sub-oesophageal ganglion, those of the fifth segment from the back of the ganglion. The stomatogastric nervous system is also described. The entire nervous system shows little specialization compared with that of most other errant polychaetes.
Some Observations on the Glycogen of the Wool Follicle
Authors: Ryder M. L.
Published: April 2021

The distribution of glycogen in the wool follicle is described; its presence, until recently unsuspected, has been demonstrated in the unkeratinized part of the fibre. The deposition of glycogen in the follicle has been investigated by injecting mice with glucose labelled with carbon-14.

The distribution of acid and alkaline phosphatases is described ; the former appears to be concentrated in the unkeratinized part of the fibre and the latter in the bloodvessels of the follicle.
A Note on the Preservation of Adipose Lipid
Authors: Chou J. T. Y.
Published: April 2021

The lipid globules of adipose cells become insoluble in fat solvents after they have been fixed in a suitable fixative and postchromed for 7 weeks at 37° C. The potassium dichrofnate acts merely as an oxidizing agent: little or no chromium is left in the globules.
The Histochemistry of Bound Lipids
Authors: C. Berenbaum M.
Published: April 2021

Many tissue-lipids are bound in varying degrees to other substances, mainly protein, and so are resistant to extraction by organic solvents. Such bound lipids are still present in paraffin sections, but they cannot be satisfactorily demonstrated by conventional use of the Sudans. It has been found that an essential condition for such demonstration is their prior dissociation from their complexes by hydration, heat, or the action of proteolytic enzymes.

Methods are described by which, after routine fixation, bound lipids may be partially dissociated from their complexes and then demonstrated by Sudan black, in paraffin sections or in smears.

These methods show lipids to be present constantly in association with nuclear and cytoplasmic nucleoprotein, in basement membranes, epithelial brush borders, neurones, and many other structures. There is evidence that these lipids do not form a homogeneous class, but vary widely in their physico-chemical natures.
The Effect of reversing the Internal Water-Current on the Spicule Orientation in Leucosolenia variabilis and L. complicata
Authors: Jones W. Clifford
Published: April 2021

Specimens grown in quiet water in an aquarium tank produce the same pattern of spicules as do those occurring naturally. Woodland’s hypothesis, that the orientation arises from turbulence in the environment, is thereby disproved. Reversing the internal water-current in excised oscular tubes of Leucosolenia has shown that no direct causal relationship exists between the direction of the current and the orientation of the spicules. The spicule arrangement is modifiable by experiment; the orientation is not dependent on the existence of static structural features in the wall of the sponge. Removal of the oscular rim has little effect on the orientation of the spicules subsequently developing in the tube behind. Diverticula develop from bulges, formed largely by a reshaping process. The arrangement of the associated small spicules is essentially the same as for L. lieber- kilhnii. A mechanical hypothesis explaining the orientation of the spicules is briefly described. The formative cell sextet is believed to be oriented by a movement of the mesogloea over the epithelium to which the sextet is contiguous.
The Ultra-fine Structure of Lipid Globules in the Neurones of Helix aspersa
Authors: Chou J. T. Y. , Meek G. A.
Published: April 2021

The three kinds of lipid globules recognizable in the living neurones of Helix aspersa have been examined under the electron microscope. The globules of the kind that can be stained blue with methylene blue during life are seen in electron micrographs as spheres or spheroids, with concentric lamination, after calcium-osmium fixation. After fixation with sucrose-osmium laminated crescentic bodies are seen instead ; these appear to be formed by distortion of the ‘blue’ globules. The yellow globules contain electron- dense material, and sometimes appear reticular. It is possible that the yellow globules may originate by transformation of some of the ‘blue’ globules. The colourless globules generally appear as crenated objects; this appearance may be a shrinkage artifact.

Apart from the mitochondria and the three kinds of lipid globules described, no other object large enough to be identified with the light microscope has been seen in the cytoplasm.
Experiments on the Fixation of Lipids by Osmium Tetr oxide
Authors: Chou J. T. Y.
Published: April 2021

The black material seen in paraffin preparations of tissues fixed with osmium tetroxide is not merely reduced osmium. The lipid is still present in combination with osmium. Osmicated lipid globules are insoluble in chloroform or benzene. They regain their solubility in lipid solvents when the blackness caused by osmium tetroxide is bleached away.
Osmotic And Ionic Regulation in the Shore Crab, Carcinus Maenas, with Notes on the Blood Concentrations of Gammarus Locusta and Ligia Oceanica
Authors: Bateman J. B.
Published: April 2021

The influence of some foreign ions and non-electrolytes on the relation between the chloride concentration and vapour pressure of the blood of Carcinus and the external solution has been studied. The added substances showed interesting specific effects, which are discussed in the text, but no general conclusion can be drawn. It is very probable, however, that the gill membrane is almost impermeable to water, so that osmotic forces, as such, play no part in producing the observed relationships between blood and the external medium. There is no evidence for active water regulation in Carcinus. The latter conclusion is supported by experiments on the effects of cyanide and hypertonic solutions. In the latter case, in spite of “osmotic” regulation being abolished, no significant water transfer occurs. Miscellaneous experiments on the result of varying pH and temperature are described ; in each case the effects are surprisingly small. In a single experiment, the isolated gill tissue of Carcinus showed no secretory activity. The method used, based on Hill’s “bound water” technique, is described in detail. An analysis of the dilution-time curves for Carcinus in dilute solutions suggests that the process is accompanied by considerable changes in the properties of the gill membrane, before the beginning of the real regulatory mechanism. The same data permit the calculation of the work done in maintaining the steady state, but the result is improbably high. A direct study has been made of the vapour pressure of the body fluid of Ligia oceánica living under various conditions. For short periods of immersion in dilute solutions the animals show a high degree of osmotic independence, but their resistance breaks down on prolonged immersion. A method was tested for the study of internal concentration changes in animals too small for direct measurement. The results of an experiment on Gammarus locusta are discussed.
The Electrical Properties of Frog Skin
Authors: Francis W. L. , Pumphrey R. J.
Published: April 2021

This paper is the first of a series in which the results of a study of the electrical properties of frog skin will be presented. Frog skin is a convenient material for bio-electric investigation. It is easily obtained, can bé mounted as a membrane and gives high potentials (ca. 40-−70 millivolts between opposite sides of the skin). On the other hand the complexity of structure of the skin tissue makes it difficult to determine which cells are the seat of the potential. Considerable insight has, however, been gained during this work into the chemical and physical processes by which the electrical potential is maintained. This is of interest in relation to the general problem of the nature and origin of bio-electric potentials.
Studies in Animal Locomotion
Authors: Gray J.
Published: April 2021

In a previous paper (Gray, 1933) the propulsive thrust of an eel’s body has been expressed in terms of the transverse movements of each region of the body. Since the changes in the position and in the form of each region are the result of rhythmical muscular activity, it should be possible to describe, in a qualitative way, the propulsive thrust in terms of the form and velocity of the metachronal waves which pass over the surface of the body.
Inactivation of Octopamine in Larval Firefly Light Organs by a High-Affinity Uptake Mechanism
Authors: Carlson Albert D. , Evans Peter D.
Published: April 2021

Uptake studies using radioactive octopamine have revealed that the larval lantern of the Photuris firefly possesses a concentrative, high-affinity uptake system for octopamine. This compound has been shown previously to be the neurotransmitter of the photomotor neurones. Imipramine is a potent inhibitor of the uptake of octopamine in the lantern. At 10−5mol l−1, it reduces specific uptake of radioactive octopamine with a K, of 5·8 × 10−6 mol l−1. Incubation of lanterns in 2·5 × l0−4mol l−1 imipramine induces an increase in sensitivity of the luminescent response to endogenously released and exogenously applied octopamine. Release of endogenous octopamine is potentiated in imipramine-treated lanterns, which also show a significant reduction of octopamine content with this treatment. Uptake of octopamine does not appear to be affected by denervation of the lanterns, suggesting that nerve terminals are not the principal sites of octopamine uptake.
Cardiovascular Responses in the Sea Raven, Hemitripterus Americanus, Elicited By Vascular Compression
Authors: Farrell A. P.
Published: April 2021

Increases in the water pressure (Pw) around the trunk of the sea raven (Hemitripterus americanus Gmelin) were used to evaluate the effects of vascular compression on cardiovascular variables. Cardiac output , heart rate (fH) and blood pressures in the ventral aorta, dorsal aorta and ductus Cuvier (Pva, Pda and Pdc, respectively) were measured. A 20 cmH2O increase in Pw decreased vascular conductance by up to 25 %. During vascular compression, a reflex bradycardia reduced Vb and attenuated the accompanying rise in arterial blood pressure. Pretreatment of the fish with the sympathetic antagonist, propranolol, further attenuated the hypertension by accentuating the reflex bradycardia. Subsequent pretreatment with papaverine, a vascular smooth muscle poison, potentiated these effects and did not reveal any autoregulatory vasodilation in the periphery. Atropine pretreatment completely abolished the reflex bradycardia, indicating that the bradycardia resulted from increased vagal cholinergic tone. The fish also exhibited cardiovascular compensation during the 2 min vascular compression. An accommodation of the barostatic reflex (reduced vagal tone) and a sympathetic tachycardia raised and passively increased vascular conductance. The set point for the barostatic bradycardia was apparently temperature-sensitive.
Wind Tunnel Studies of Turns by Flying Dragonflies
Authors: Alexander David E.
Published: April 2021

High-speed movies of dragonflies turning in flight on flexible tethers show that there are two distinct modes of turning. In the ‘conventional’ mode, dragonflies use left-right asymmetries in the wing stroke amplitude, and occasionally in the angle of attack, to produce more lift and thrust on one side than the other. This causes the animal to roll into a bank, so that the lift vector has a sideward component; this sideward component produces the turn, much as in an aeroplane. This type of turn is probably most useful during fast forward flight.

The second mode of turning is the ‘yaw turn’. Yaw turns are accomplished without banking, and the dragonfly’s long axis may turn more than 90° in the period of two wing strokes. The kinematics of this turn could not be as closely analysed, but it appears that dragonflies use drag on the inner wing upstroke and the outer wing downstroke to turn, much like pivoting a rowing boat. This turn may be hampered by drag on the abdomen during fast forward flight and would be most useful at low speeds or during hovering.
The Modulation of Feeding Behavior in Response to Prey Type in the Frog Rana Pipiens
Authors: Anderson Curtis W.
Published: April 2021

Using high-speed video motion analysis, the kinematics of feeding behavior was studied in Rana pipiens. Rana pipiens exhibits differing behavior patterns depending upon prey type. When feeding on small prey such as waxworms, R. pipiens uses tongue protraction to catch prey, minimizing head and body movements. When feeding on the larger earthworm, it arches its body, flexes the head downwards and uses jaw prehension to capture the prey. Time to completion of tongue retraction, time to completion of mouth closing, duration of tongue retraction, duration of mouth closing, total time that the mouth is open and maximum tongue reach were significantly longer during waxworm feedings than during earthworm feedings. The tongue angle and degree of head flexion were significantly greater during earthworm feedings. These different kinematic patterns correspond to differences in feeding behavior among major taxa of anurans. Phylogenetically primitive archaeobatrachian frogs have short tongues which can be protracted only a few millimeters. In contrast, many neobatrachians have long tongues which they project to catch small prey. The similarity between the behavior that neobatrachians use to catch large prey and the movement patterns of archaeobatrachians suggests that Rana pipiens has retained the plesiomorphic archaeobatrachian motor pattern and uses it to catch large prey, while evolving a new motor pattern for catching small prey.
Effect of Temperature on Central Chemical Control of Ventilation in the Alligator Alligator Mississippiensis
Authors: S. Branco Luiz Guilherme , Wood Stephen C.
Published: April 2021

Central chemoreceptor function was assessed in unanesthetized alligators, Alligator mississippiensis, at body temperatures of 15, 25 and 35°C. Two experiments were performed. In the first experiment, the fourth ventricle was perfused with mock cerebrospinal fluid (CSF) solutions of different pH values (7.1–7.9). Changes in pulmonary ventilation were evaluated with a pneumotachograph and arterial pH (pHa) was measured. Perfusion with low-pH solutions increased ventilation and arterial pH. Perfusion with high-pH solutions decreased ventilation and arterial pH. Mock CSF pH had a greater effect at higher temperatures. In the second experiment, the relative contributions of central and peripheral chemoreceptor drive to breathing were evaluated using hypercapnic gas mixtures to stimulate both central and peripheral chemoreceptors. Hypercapnia caused an increase in ventilation which was larger at higher temperatures. To stimulate only the peripheral chemoreceptors, the same hypercapnic gas mixtures were applied while the CSF pH of the fourth ventricle was kept constant by perfusion with a mock CSF solution. This reduced significantly the ventilatory response induced by hypercapnia. These data indicate that, regardless of the temperature, central chemoreceptors play a major role in the ventilatory regulation of the alligator. The change in pHa with temperature is compatible with the alphastat hypothesis.
Quantitative Determination of Myotropic Neuropeptide in the Nervous System of the Cockroach Leucophaea Maderae: Distribution and Release of Leucokinins
Authors: Muren J. Eric , Lundquist C. Tomas , Nässel Dick R.
Published: April 2021

Being interested in the distribution and function of insect myotropic peptides, we developed a sensitive radioimmunoassay (RIA) using an antiserum directed against the cockroach neuropeptide leucokinin I. The levels of leucokinin immunoreactivity were measured in extracts of different portions of the nervous system, in the retrocerebral complex and in the hemolymph of the cockroach Leucophaea maderae. The brain contains about 1.9pmol of immunoreactive material while the ganglia of the ventral nerve cord each contain less than 10% of this amount. Large amounts of leucokinin immunoreactivity (6.6pmol per tissue) were found in the corpora cardiaca–corpora allata (CC–CA) complex and in the hemolymph the titer was in the nanomolar range. When levels of leucokinins were compared in male and female cockroaches, no differences could be detected in any of the sample tissues. A calcium-dependent release of leucokinin-immunoreactive material could be induced from isolated CC–CA complexes by high-potassium depolarization. The amount of released immunoreactivity, as measured in the bathing saline by RIA, was about 2% of the extractable leucokinin immunoreactivity in the CC–CA complex. In Leucophaea maderae, the leucokinins apparently act both as neuroactive substances in the central nervous system and as neurohormones released into the circulation.
Modulation of Ca2+ and K+ Conductances in an Identified Insect Neurone by the Activation of an α-Bungarotoxin-Resistant Cholinergic Receptor
Authors: David Jonathan A. , Pitman Robert M.
Published: April 2021

The effects of activation of a population of α-bungarotoxin (α-bgt)-insensitive cholinergic receptors on the soma of the cockroach fast coxal depressor motor neurone (Df) have been examined under two-electrode voltage-clamp conditions. Activation of these receptors was achieved by bath-application either of acetylcholine (ACh) in the presence of α-bgt or of the muscarinic agonist McN-A-343 (McN). Since these receptors have been shown previously to respond to some nicotinic agonists, we refer to them as ‘McN-sensitive or mixed pharmacological profile muscarinic receptors’ (mMAChRs). Activation of these receptors normally results in a biphasic response consisting of an initial outward current component, which reverses near −70 mV, and a later (delayed) inwardly directed current, which is only observed at membrane potentials more positive than −40 to −20 mV.

The initial outwardly directed component of the McN-induced current appears to result from an increase in K+ conductance since it reverses at potentials close to the K+ equilibrium potential (EK) (approximately −70 mV under the experimental conditions used) and is blocked by internal Cs+. This increase in K+ conductance is probably due to an increase in Ca2+-activated K+ current (IK,Ca) which is known to form a large proportion of the outward current observed when this neurone is depolarized.

The delayed inwardly directed current induced by McN results from suppression of a Ca2+ current (ICa) which, in turn, causes a decrease in IK,Ca. The net effect is a reduction in outward current, because IK,Ca is considerably larger than ICa. Evidence for an action of McN upon Ca2+ channels is provided by experiments in which K+ currents have been suppressed by internal Cs+ to reveal inward currents produced by the movement of Ba2+ through voltage-dependent Ca2+ channels. Ba2+ currents observed under these conditions are suppressed by bath application of McN. The inwardly directed current component of the McN response is unlikely to involve direct regulation of IK,Ca, since McN has no effect upon this current when it is induced by brief intracellular Ca2+ injections.

Both the initial outwardly directed component and the delayed inwardly directed component of the McN-induced current were suppressed by intracellular injection of the Ca2+ chelator BAPTA. These observations suggest that a rise in [Ca2+]i mediates the electrophysiological effects of McN in Df somata.
Evidence That Histamine is a Neurotransmitter in an Insect Extraocular Photoreceptor Pathway
Authors: Lundquist C. Tomas , Baines Richard A. , Bacon Jonathan P.
Published: April 2021

The pair of vasopressin-like immunoreactive (VPLI) neurones of the locust Locusta migratoria have cell bodies in the suboesophageal ganglion and extensive arborization throughout the central nervous sytem. The activity of the VPLI neurone is regulated by a spontaneously active excitatory descending interneurone (DI) that is, in turn, inhibited by an uncharacterised extraocular photoreceptor (EOP) system located in the brain. Light directed at the brain results in inhibition of DI activity, which thereby deprives the VPLI neurone of its major synaptic input. We present evidence that histamine plays an important role in the EOP–DI–VPLI pathway. Histamine mimics the EOP-mediated inhibition of the DI, and the H2-specific histamine antagonists cimetidine and ranitidine block its inhibitory action. Histamine application to various areas of the brain localises the area where histaminergic inhibition occurs; this region is confined to the medial protocerebrum. At least six bilaterally paired histamine-like immunoreactive neurones send axonal projections into this area. Depolarisation of the brain region containing the soma of these neurones with high-K+ saline deactivates the VPLI neurone through the removal of the DI excitatory synaptic input.
The Trap-Jaw Mechanism in The Dacetine Ants Daceton Armigerum and Strumigenys Sp.
Authors: Gronenberg Wulfila
Published: April 2021

Ants of three different subfamilies, among them the tribe Dacetini, have evolved very fast snapping mandibles called trap-jaws. The two dacetine genera examined, the large Daceton and the small Strumigenys, employ the same mechanism for their mandible strike. Video analysis reveals that, in Strumigenys sp., the strike takes less than 2.5 ms. It is released within 5 ms by contact of trigger hairs on the labrum. The ants employ a catapult mechanism to generate such a fast movement. Before the strike, the mandibles are opened wide and locked in the open position by the labrum, which functions as a latch. They stay open even when the large slow closer muscles contract. Upon trigger hair stimulation, the labrum is pulled backwards by a small, fast trigger muscle. The mandibles are thus freed from the catch and close rapidly. This reflex is controlled by giant sensory and motor neurones in the labral neuromere that are probably monosynaptically coupled. The short latency of the reflex thus results from the combination of a catapult mechanism, fast trigger muscles, high neuronal conduction velocities and small synaptic delays. Comparison with the trap-jaw mechanism of the ant genus Odontomachus reveals a remarkable example of convergent evolution.
Homing Experiments on Pigeons Subjected To Bilateral Destruction Of The Paratympanic Organ
Authors: Giannessi F. , Fattori B. , Ruffoli R. , Gagliardo A.
Published: April 2021

The paratympanic organ (PO) in birds is a specialised sensory organ whose function is still unknown. G. Vitali, who first described the PO from observations of the behaviour of PO-lesioned pigeons, proposed that this organ was needed to maintain normal wing muscle function and called it the ‘organ of flight’. This interpretation has since been disputed. To solve this controversy and to test whether the PO is involved in flight and navigation, we performed release tests on homing pigeons subjected to bilateral destruction of this organ. No impairment of either flight or navigation was observed in the lesioned pigeons.