bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method for High-power Stereoscopic Microscopy
Authors: Galbraith W. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
‘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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACTThe 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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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.