bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trimorphism in the Ichneumonid Parasite Geliscorruptor
Authors: SALT GEORGE 
Published: April 2021

ABSTRACT
The ichneumonid parasite Gelis corruptor is trimorphic in the development of wings: females are invariably apterous; males may be either macropterous or micro-pterous. Females show no trace of wing-buds in the pupa and are without wing-disks in the late larval stage. The female apteryis a sex-limited character and is of genetic origin. All male larvae have wing-disks and are potentially fully winged males. On a host providing adequate nourishment, the male larva develops into the macropterous form; on a host providing meagre nourishment, it develops into the micropterous form. Eggs or young larvae transferred from a small to a large host develop into macropterous males ; larvae removed from large hosts before they have finished feeding develop into micropterous males. The dimorphism of the male sex is therefore controlled by the host viewed as a quantity of food. The two forms of males differ not only in the development of the wings but also in the structure of the thorax, the size of the ocelli, the form of the endoskeleton, and the development, innervation, and tracheal supply of the thoracic muscles. The trimorphism is strict, since all females are apterous and (with the exception of one abnormal specimen) all the males examined belong without intermediates to either the macropterous or the micropterous form. The principal differences observed between the three forms all appear to be bound up with the condition of the wings. How the development of this complex of characters is organized, particularly in the two forms of males, presents an interesting problem of morphogenesis.
Enucleation of Sea-Urchin Blastomeres with or without Removal of Asters
Authors: Lorch I. Joan 
Published: April 2021

ABSTRACT
The following experiments were carried out on one blastomere at the two-cell stage of the sea-urchin egg:
1.Removal of the nucleus.
2.Removal of the nucleus and surrounding cytoplasm (centrosphere).
3.Attempted removal of the centrosphere only.
In cells from which the nucleus had been removed the asters multiplied for up to 7 hours and then disappeared. During the period of aster multiplication, cleavage furrows often appeared between the asters but did not succeed in dividing the cell. After about 8 hours, cleavage into a large number of spheroidal cells occurred.
When the nucleus and centrosphere were removed no asters were formed and no cleavage furrows were observed until after about 8 hours, when division into a large number of spheroidal cells occurred.
When attempts were made to remove the centrosphere, leaving the nucleus intact, asters were always eventually re-formed. Before the re-formation of asters neither the nucleus nor the cytoplasm divided although dissolution of the nuclear membrane, followed by its reappearance, occurred. After re-formation of the asters cleavage appeared to be normal.
Some Structural Proteins of Mytilus Edulis
Authors: Brown C. H. 
Published: April 2021

ABSTRACT
The byssus threads, periostracum, hinge, ground substance of the shell, and the supporting material of the gills of Mytilus edulis, have been examined by physical, chemical, and histochemical means. The byssus threads, periostracum, and hinge have been shown to consist of a quinone-tanned protein. The byssus threads are formed in the posterior groove of the foot from the secretions of two glands, the ‘white ‘gland which supplies the bulk of the protein of the thread, and the ‘purple ‘gland which supplies the aromatic material responsible for the tanning. The periostracum is secreted by gland cells in the epithelium of the outer lobe of the mantle edge. The supporting material of the gills is a fibrous protein without quinone-tanning. This protein is in some respects similar to the untanned protein of the byssus.
Studies of the Mesogloea of Coelenterates: I. Histology and Chemical Properties
Authors: Chapman Garth 
Published: April 2021

ABSTRACT
Evidence is presented to show that the mesogloea of the coelenterates examined, including Aequorea, Aurelia, Cyanea, Chrysaora, Calliactis, and Metridium contains collagen-like material in the form of fibres of varying sizes. Cells are also present in the mesogloea of some species but there is little evidence concerning their functions.
In Aequorea and the Scyphozoa examined the fibres appear to be straight and very transparent in life but on injury and fixation they adopt a convoluted and irregular appearance. Cells are present in Aurelia and form about 0· per cent, of the mesogloea by volume but are absent from the other medusae examined. The mesogloea of actinians is of a more densely fibrous character than that of medusae. In Calliactis and Metridium the crossed fibrillar structure present is determined by mechanical forces acting on the tissue.
Reference is made to the physical properties of Calliactis mesogloea, which are described in another paper. The material is tough, almost resembling cartilage in its consistency, and has considerable tensile strength.
The chemical nature of the mesogloea is shown to be primarily that of a protein of which the amino-acid composition is similar to that of vertebrate collagen.
The role of the mesogloea in the life of the animal is that of a base for the muscles, a limiter of the body volume, and a resister of rapid movements, both those caused by the musculature and those enforced by the environment without. Its viscous-elastic properties are well adapted to this role since the elastic component, having a short timescale, can provide a restoring force for rapid deformations.
The Ability to Differentiate, and the Size of Regenerated Cells, after repeated Regeneration in Spongilla Lacustris
Authors: Brøndsted H. V. 
Published: April 2021

ABSTRACT
The findings presented here have a bearing on regeneration in general. They show that even in simply organized animals, the number of totipotent cells which are able to differentiate decreases as the individual ages. In older specimens it takes longer for the totipotent cells to differentiate than in younger ones ; at the same time the nuclear and cytoplasmic volume of these cells is reduced.
The expanded basal epithelium of sponges germinating from gemmules is an organ necessary to establish the tension in the body which is indispensable for the functioning of the sponge. Sponges that have germinated from gemmules can be forced to regenerate a basal epithelium. The materials for this regeneration is furnished by the archaeocytes, which are embryonic, totipotent amoebocytes. The number of archaeocytes that are able to perform this regeneration decreases with time, i.e. as the differentiation of the entire body proceeds.
On the other hand, the ability of the sponge to expand repeatedly on its own basal epithelium after being pushed away from it is limited only by the onset of cytolysis.
The ability of the archaeocytes to regenerate new typical basal epithelial cells is reduced after repeated regeneration.
The size of both nucleus and cytoplasm is reduced more and more during repeated regeneration. The nucleo-cytoplasmic ratio is thus kept fairly constant.
Cytological Studies of the Neurones of Locusta migratoria Part III. Histochemical Investigations, with Special Reference to the Lipochondria
Authors: Shafiq Saiyid Ahmad , Casselman W. G. Bruce 
Published: April 2021

ABSTRACT
The motor neurones of the thoracic ganglia of adult Locusta migratoria have been studied by in situ histochemical techniques. Phospholipides and unsaturated cerebrosides are concentrated in the lipochondria; acetalphosphatides, cholesterol, protein, and ribonucleic acid are diffusely present throughout the cytoplasm; little nucleic acid is demonstrable in the nuclei.
Lead Tetra-Acetate/Schiff Tests in Histochemistry
Authors: Casselman W. G. Bruce 
Published: April 2021

ABSTRACT
Certain polysaccharides, such as starch and glycogen, do not give consistently positive or negative reactions with all lead tetra-acetate/Schiff techniques. This depends upon the conditions under which the oxidant is used. A simple glacial acetic acid solution of lead tetra-acetate is least active but most specific. Added potassium acetate acts as a catalyst. Dilution with water not only increases the activity of the reagent but also decreases the specificity of the test.
The Histochemical Déphosphorylation of Riboflavin Phosphate (Flavin Mono-nucleotide) and Pyridoxal Phosphate (Co-decarboxylase)
Authors: Bourne Geoffrey H. 
Published: April 2021

ABSTRACT
The histochemical dephosphorylation of riboflavin phosphate and pyridoxal phosphate has been studied at pH 9·0 and pH 5·0. The results have been compared with those obtained with glycerophosphate. It was concluded that these substrates are dephosphorylated by enzymes or enzyme systems differing from each other and from that which dephosphorylates glycerophosphate. The vitamin substrates undergo some dephosphorylation by all tissues examined at pH 9·0. At pH 5·0, however, no reaction is given by any tissue with riboflavin phosphate as a substrate, but all tissues give some reaction at this pH with pyridoxal phosphate. The reaction at both acid and alkaline pHs with pyridoxal phosphate is in some tissues located in bodies resembling mitochondria: the sarcosomes of heart-muscle in particular give a strong reaction. This is true at pH 9·0, to a lesser extent, with riboflavin phosphate. It is possible that the sites of dephosphorylation shown by the histochemical tests may also be the sites of phosphorylation of these vitamins. Intercalated disks of heart-muscle show an intense dephosphorylating activity for riboflavin phosphate and glycerophosphate. Pyridoxal phosphate and riboflavin phosphate are dephosphorylated at the same sites (differentiating regions) as glycerophosphate in rat embryos.
The Epicuticle of an Arachnid, Palamneus swammerdami
Authors: Krishnan G. 
Published: April 2021

ABSTRACT
The epicuticle of Palamneus swammerdami in the unhardened condition is homogeneous. It stains uniformly red with Mallory. When hardened, it comprises an internal unstained region, giving evidence of —S—-S— bonding, and is bounded externally by a very thin membrane which stains blue with Mallory.
The protein of the inner basal layer differs from its counterpart in the insect epicuticle in the absence of tyrosine, in the occurrence of cystine and cysteine, and in being resistant to the action of hot alkalis. Though apparently related to the keratin of vertebrates, it is not identical with it. The outer thin membrane is lipide in nature. X-ray diffraction studies show that the epicuticular protein is unique: it is unlike both arthropodin and the keratin of vertebrates. However, the outer membrane of the epicuticle yields a diffraction pattern indicating the presence of long-chain paraffins and is similar to the outer epicuticle of the blowfly larva. The chitin of the cuticle appears to be identical in pattern with that of insects.
In spite of differences in structural and chemical constitution, the epicuticle of the scorpion shows a resemblance to the basic pattern of the insect epicuticle. The differences may be attributed to the absence of phenolic tanning and the occurrence of —S—S— bonding. The possible role of the purines present in the cuticle of the scorpion is discussed in relation to —S—S— bonding.
A Study of the Osmium Techniques for the ‘Golgi Apparatus’
Authors: Baker John R. 
Published: April 2021

ABSTRACT
The paper is concerned with the action of the osmium techniques for the ‘Golgi apparatus’ on the intestinal epithelial cell of the mouse. It is shown that, when the fixative has acted, there are many separate lipide spheres in the ‘Golgi’ region. During postosmication the spaces between these spheres are filled up with a black precipitate. This black precipitate does not represent the distribution of lipide material.
The Action of Fixatives on the Ultra-violet-absorbing Components of Chick Fibroblasts
Authors: Davies H. G. 
Published: April 2021

ABSTRACT
This paper describes an investigation by ultra-violet spectrometry of the physical and chemical changes caused by treating interphase chick heart fibroblasts, grown in tissue culture, with a variety of fixatives. The same cells, before and after fixation, were photographed either at 265 and 313 mμ or at a series of wavelengths required for an absorption spectrum. The nucleus of the living interphase cell, apart from nucleoli, is nearly homogeneous, and non-specific light loss measured by the optical extinction at 313 mμ (E313) is not detectable. After fixation the nuclear material is redistributed into filamentous and rounded structures. These nuclear structures are least apparent after osmium tetroxide, methanol freezing-substitution, and freezing-drying; may be more marked after 10 per cent, neutral formalin; and are very marked after Carnoy fixation. E313 is measurable in a fixed nucleus and the ratio of optical extinctions E313/E265 is always less than about 15 per cent. E265 increases as a result of the shrinkage of the nuclear area which ranges from about 8 to 16 percent, for osmium tetroxide, about 5 to 35 percent, for neutral formalin, about 19 to 47 per cent, for Carnoy, and about 20 to 40 per cent, for freezing-substitution. Apart from occasional cracks in cells, freezing-substitution and freezing-drying preserved nuclear and cytoplasmic structure as well as osmium tetroxide. (i) Total nuclear extinction is defined as average nuclear extinction times nuclear projected area. Decreases in total nuclear extinction at 265 mμ, after fixation in Carnoy and neutral formalin, range from 10 to 35 per cent, and may be attributed to losses of absorbing material. After formalin fixation there is a decrease of approximately 40 per cent, in the total cytoplasmic extinction at 265 mμ. The method of correcting for non-specific light loss and other possible sources of error are discussed. (ii) Osmium tetroxide itself absorbs in the ultra-violet and ‘stains’ the cell, thereby increasing the optical extinction. The staining reaction was studied by fixing films of protein, fat, and nucleic acid. (iii) After methanol freezing-substitution the total extinction of the nucleus increases slightly. The ratio of optical extinctions E265,/E280 for the living nucleus is about 2·0 and by applying the methods of curve analysis due to Caspersson it is concluded that the amount of ‘standard protein’ in the nucleus is small compared with the amount of nucleic acid. After all methods of fixation E265/E280 decreases to about 13 and similarly it is concluded that the fixed nucleus contains about ten to twenty times as much ‘standard protein’ as nucleic acid. This curious result is discussed and several possible explanations suggested. It is concluded that the derivation of relative amounts of protein and nucleic acid by analysis of the absorption spectra of either living or fixed cells should be treated with caution.
On the Structure and Adaptations of Pandora inaequivalvis and P. pinna
Authors: Allen J. A. 
Published: April 2021

ABSTRACT
The two British species of Pandora are adapted for life on muddy-sand. P. inaequivalvis is taken from very sheltered shores at low-water mark and down to 10 fathoms. P. pinna is taken from depths of over 40 fathoms.
Both species are markedly inequivalve. This is probably connected with the habit of lying horizontally.
The mantle muscles and the ciliary mechanisms of the mantle and gills are described.
An account of the morphology and the functioning of the stomach is given and various modifications, due to the reduced typhlosole, are described.
Refractometry of Living Cells Part II. The Immersion Medium
Authors: Barer R. , Joseph S. 
Published: April 2021

ABSTRACT
This paper continues the discussion of an immersion method of refractometry of living cells, the basic principles of which were given in Part I (Barer and Joseph, 1954). A suitable immersion medium should be non-toxic, must not penetrate the cell, and must be in osmotic equilibrium with it so that no change in volume (and hence in concentration) occurs. These requirements are best met by solutions of substances of high molecular weight. The effects observed when cells become freely permeable to such substances are described. An account of tests with various immersion media is given. The main substances tried have been peptone, proteose, protein hydrolysate, dextran, polyvinyl alcohol, polyvinylpyrrolidone, acacia gum, egg albumin, bovine gamma globulins, carboxyhaemoglobin, and bovine plasma albumin. Of these, bovine plasma albumin has proved to be most generally useful though acacia gum may be a good inexpensive substitute for some cells, particularly fungi.
The osmotic properties of the immersion medium are most important and must be carefully controlled if true determinations of solid concentration are to be made. Some of the many difficulties in defining an isotonic physiological medium are reviewed. It is suggested that the best practical definition is that such a medium should be innocuous and should not change the cell volume. A method of adjusting the salt content of the medium, based on this definition, is described, and the possibility that some cells may exhibit a degree of osmotic regulation is discussed. Finally, evidence is presented to demonstrate the harmlessness of the isotonic protein medium to many types of cells. Photomicrographs of cell division over a period of 48 hours in a protein medium are shown.
Neoteny with Goitre in Triturus helveticus
Authors: Dodd J. M. , Callan H. G. 
Published: April 2021

ABSTRACT
A population of newts from a pond near Crail, Fife, was found to contain neotenic and goitrous specimens of Triturus helveticus in 1951 and 1952 but not in 1953 and 1954. This is a unique record of goitre among amphibians.
The thyroid glands of normal adult and neotenic non-goitrous T. helveticus are paired spheroidal or ellipsoidal bodies whose longest dimension varies between 300 and 700 ft. They consist of a few large follicles. The thyroid glands of the goitrous neotenic specimens may be as much as 4 mm. long. They are extremely hyperplastic and hyperaemic and for the most part consist of follicles smaller than those charac- teristic of normal newt thyroids. These goitrous thyroids produce major displacement of other structures in the throat region but do not invade other tissues.
It is suggested that the goitres result from the exposure of overwintering newt larvae to the ‘brassica factor’ carried to the pond in the faeces of rabbits feeding on turnips and kale in neighbouring fields.
The Histochemical Localization of β-Glucuronidase in the Digestive Gland of the Roman Snail (Helix pomatia)
Authors: Billett F. , Mcgee-Russell S. M. 
Published: April 2021

ABSTRACT
A modification of the histochemical technique for the localization of β-glucuronidase originally suggested by Friedenwald and Becker (1948) has been applied to the digestive gland of the gastropod Helix pomatia. In the original technique the ferric 8-hydroxyquinoline formed by the enzymic hydrolysis of quinolyl-8-glucuronide, in a saturated golution of ferric 8-hydroxyquinoline, was converted to Prussian blue. The Prussian blue conversion is omitted in the technique described in this paper as it appears to introduce errors in localization. The ferric 8-hydroxyquinoline crystals are sufficiently characteristic to be used as the end-point of the technique. The results obtained suggest that β-glucuronidase is confined to the digestive cells in the digestive gland of the snail, and is associated with secretory granules in them.
Respiratory and Cardiac Performance inLolliguncula Brevis(Cephalopoda, Myopsida): The Effects of Activity, Temperature and Hypoxia
Authors: Wells M. J. , Hanlon R. T. , Lee P. G. , Dimarco F. P. 
Published: April 2021

ABSTRACTLolliguncula brevis Blainville is a small euryhaline squid found at temperatures between 11 and 31 °C. Changes in heartbeat and ventilation frequencies were observed throughout this temperature range and under a variety of conditions, including acute hypoxia and swimming by jet propulsion in a tunnel respirometer. Resting showed a Q10 of 1·47, and heart rate and ventilation rate Q10 values of 1·92 and 1·73, respectively; oxygen uptake could exceed 1·01kg−1h−1 at 30°C even at rest. The squids regulated their oxygen uptake at all temperatures. Oxygen extraction rates were in the region of 5-10% in saturated water, increasing to 15-20% in hypoxic water or after exercise. One effect of this variability is that ventilation stroke volume can remain constant throughout the range of temperatures and oxygen concentrations that the animal is likely to encounter, a necessary condition since the ventilation stream is also the principal mode of locomotion by jet propulsion. Blood oxygen-carrying capacity (from the copper concentration) was 4·6 ± 1·8 vols%. Cardiac output and stroke volume were estimated from the observed values and heartbeat frequencies. Resting at 25°C, the output was close to ll-51kg−1bodymassh−1. The systemic heart of Lolliguncula weighed only 2·06 ± 0·62 g kg−1. In exercise the cardiac output must exceed 14x 1031kg−1 heart mass h−1, pumping more than the heart’s own mass of blood at each stroke.
The Action of Vasoactive Intestinal Peptide Antagonists On Peptidergic Modulation of the Squid Schwann Cell
Authors: Evans Peter D. , Villegas Jorge 
Published: April 2021

ABSTRACT
The effects of two specific antagonists of vasoactive intestinal peptide (VIP) receptors were investigated on the VIP-induced hyperpolarization of the membrane potential of the Schwann cell of the giant nerve fibre of the tropical squid. Both (pCl-D-Phe6,Leu17)VIP and (N-Ac-Tyr1,D-Phe2)-GRF(l-29)amide competitively and reversibly blocked the effects of VIP in this preparation with the former compound being more potent than the latter. The blocking actions of both antagonists were specific for the responses of this preparation to VIP. They did not block the actions of carbachol, DL-octopamine or substance P. Both antagonists also reduced the effectiveness of an endogenous VIP-like component in the normal hyperpolarizing action of giant axon activity on the membrane potential of the Schwann cell, with the same potency ratio as for their actions on the effects induced by the exogenous application of VIP.
Kinematics of Swimming in Two Species ofIdotea(Isopoda: Valvifera)
Authors: Alexander David E. 
Published: April 2021

ABSTRACTIndividuals of Idotea resecata and I. wosnesenskii were videotaped at 200 frames s∼1 while swimming freely. Propulsion is provided by the first three pairs of abdominal appendages (pleopods), which may also function as gills. Unlike typical crustacean metachronal beating, in Idotea all three pairs of propulsive pleopods begin their recovery strokes simultaneously. Each pair then carries out its power stroke in sequence: third pleopods have a short power stroke, then second pleopods have an intermediate power stroke, finally first pleopods have a long power stroke. After these power strokes, there is a pause before the next recovery stroke begins. The duration of the power stroke of any pair of pleopods, as well as the overlap with other pleopods’ power stroke, is variable and is not directly related to swimming speed. Stroke amplitude is approximately constant, but stroke frequency is significantly correlated with swimming speed. Other stroke variables which could affect swimming speed are also loosely correlated with frequency, but it appears that frequency is the most important determinant of swimming speed. The unusual stroke pattern in Idotea may be related to the respiratory function of the pleopods.