bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Nature of Immunity to Homologous Grafted Skin, With Special Reference to the Use of Pure Epidermal Grafts
Authors: Billingham R. E. , Sparrow Elizabeth M. 
Published: April 2021

ABSTRACT
Homografts of pure epidermis, i.e. of skin freed from all dermal elements, survive their orthotopic transplantation between unrelated rabbits for 10-15 days. They elicit and succumb to a transplantation immunity reaction just as ordinary skin homografts do. The distinctive sequence of histological changes that take place in the dermis of a skin homograft during the course of its breakdown take place in the host’s own young fibrous tissue when this forms the bed underlying pure epidermal homografts. Although the breakdown of pure epidermal homografts is accelerated when they are transplanted to specifically immunized recipients, they normally survive for from 4-6 days. It is inferred that the serum and tissue exudates present in the bed to which such grafts are transplanted have no immediate inimical effect on the susceptible Malpighian cells when these are intimately exposed to them. The possible application of pure epidermal grafts, and more particularly of dissociated epidermal cells, has been investigated in attempts to demonstrate a specific toxic action against a donor’s cells of the blood, serum, and other derivatives of specifically immunized animals. After treatment in vitro, the ‘vitality’ of the epidermal grafts or cells was tested by transplanting them back to the animal from which they originated. It was found that epidermal melanocytes of guinea-pig’s skin are unaffected by prolonged treatment in vitro with ‘immune ‘blood and serum, with or without the addition of lymphocytes or spleen cells. The capacity of dissociated Malpighian cells in the rabbit to give rise to epithelium after grafting was completely or partially inhibited by treating them in vitro with excess immune serum for 22 hr. or longer at either 50 C. or 37° C. It is suggested that this effect indicates the presence of a protective iso-antibody in the serum of rabbits which have reacted against skin homografts. The probable role of this antibody in the breakdown of skin homografts in vivo is discussed.
Functions of the Omasum in the Stomach of the Sheep
Authors: Gray F. V. , Pilgrim A. F. , Weller R. A. 
Published: April 2021

ABSTRACT
The processes which occur in the omasum of the ruminant have long been a subject of speculation and debate (Favilli, 1937). It was at first thought that the fluid portion of the digesta passed on from the reticulum was squeezed out in the omasum, and the larger food particles comminuted there, but no evidence has been offered which proves that either of these processes actually take place. As an alternative explanation of the characteristically high concentration of solids in the omasum it was later suggested that large amounts of water might be absorbed through the walls of the organ, and this suggestion has recently received strong support from the observation (Garton, 1951) that the concentrations of certain inorganic ions are often much higher in the omasal fluid than in the rumen fluid. Nevertheless, the possibility of permeation of the omasal wall by these ions makes them unreliable as accurate markers of the absorption of water; and the further possibility that some of the reticular contents may bypass the omasum and flow directly to the abomasum via the omasal groove has rendered equivocal the use of markers for the assessment of the extent to which water is absorbed. It has been suggested (Elsden, Hitchcock, Marshall & Phillipson, 1946) that the greater part of the fatty acids in solution in the liquid portion of the material received from the reticulum are absorbed from the omasum, but here again the evidence is incomplete because of lack of knowledge of how liquids and solids are passed through the omasum. Fatty acids are undoubtedly absorbed there (Barcroft, McAnally & Phillipson, 1944), and the ratio of acids to solids is much reduced (Elsden et al. 1946), yet if fluid were separated from the solids mechanically, rather than absorbed through the walls of the omasum, the absorption of fatty acid need not be as extensive as has been implied.
The Effects of High Hydrostatic Pressures on A Suctorian
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
The suctorian Discophrya piriformis Guilcher has been subjected to pressures ranging from 1000 to 15,000 lb./sq.in. (68–1020 atm.). Pressures of 2000 lb./sq.in. and over cause a creasing of the body surface. Except at the higher pressures this occurs some seconds after the application of pressure. Creasing is accompanied by an expansion of the pellicle. At the lower pressures, there is also an expansion of the protoplasmic surface. A comparison may be made with the expansion of the body surface which occurs during feeding. In many cases, and particularly at the higher pressures, the protoplasm later separates from the expanded pellicle. With prolonged treatment it sometimes rounds up, and there is evidence of a loss of volume of the protoplasm. On release of pressure the protoplasm spreads back to the pellicle, usually within a few minutes. The wrinkled and expanded pellicle is then slowly reorganized to its normal shape and size, over a period of many hours.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
A study has been made of the effects of sudden changes of temperature on the contractile vacuole of the suctorian Discophrya piriformis Guilcher. A sudden increase of temperature from below 15° C. by 5° or more causes a temporary fall in the rate of output, followed by a rise to a new level higher than the original. During the depression in activity the body swells slightly. The vacuolar frequency increases immediately but briefly when the temperature is raised, falls steeply when the depression sets in, and when secretion is re-established rises again to a level above the original. A sudden fall in temperature causes an immediate decrease in vacuolar frequency, followed by a partial restoration. The rate of output falls rather more slowly and remains low. In several cases a small decrease in body volume was observed. It is suggested that the contractile vacuole is really contractile. The observations on vacuolar frequency described in this paper are interpreted in terms of an inherent vacuolar rhythm which is modified by temperature and which is partially linked with rate of secretion.
Slow Contraction and Its Relation to Spontaneous Activity in the Sea-AnemoneMetridium Senile(L.)
Authors: Batham E. J. , Pantin C. F. A. 
Published: April 2021

ABSTRACTIt has been known for some time that the most rapid reflex contractions of sea-anemones show a characteristic relation to the stimulus. Thus in Calliactis parasitica a short series of adequate electric shocks, given at a frequency of about 1 per sec., is regularly followed by a facilitated contraction of the marginal sphincter (Pantin, 1935a, b). That is, each successive shock sets up a nervous impulse which facilitates the response of the muscle to the next; so that the contraction increases by steps corresponding to the shocks. The facilitating effect of each impulse decays so that as the frequency of stimulation is lowered the response becomes smaller and finally vanishes.
The Activity of Slugs
Authors: Dainton Barbara H. 
Published: April 2021

ABSTRACT
Slug activity is associated with conditions of high humidity, and this association has, not unnaturally, led to the hitherto untested assumption that it was in some way induced by the necessarily damp conditions. The experimental examination of this phenomenon, described in this paper, has shown that certain changes in temperature, and not conditions of high humidity, induce activity. Such temperature changes occur in the situations inhabited by slugs on just those occasions when slug activity is observed in the field.
The Oxygen Uptake of the Lobster (Homarus Vulgaris Edw.)
Authors: Thomas H. J. 
Published: April 2021

ABSTRACT
In sea water the oxygen uptake of Homarus vulgaris is directly proportional to the oxygen concentration. The relationship applies over the temperature range 6-18° C. Within specified limits of size and condition, oxygen uptake is the same for both sexes. The relative oxygen uptake in sea water decreases as the weight of the animal increases. Oxygen uptake in sea water is effected mainly through the gills. The abdominal swimmerets, however, also serve in respiration and account for approximately 3 % of the total oxygen uptake. In sea water of constant oxygen tension, oxygen uptake increases with increasing temperature. Increase in oxygen uptake with temperature in sea water is mainly brought about by an increase in the gill ventilation rate. In addition, the degree of utilization increases. The relationship is a direct reflexion of the increased metabolic activity. The ventilation rate of gills is unaffected by a decrease of oxygen. The percentage of oxygen extracted by the gills increases as the oxygen concentration of the medium decreases. Under the influence of carbon dioxide respiratory movements become retarded at acidities greater than about pH 7·0 and are completely inhibited at around pH 6·5. At acidities less than pH 7·0 changes in the carbon dioxide concentration are without effect on the rate of the respiratory movements. The oxygen uptake in air, notwithstanding its low level, is directly proportional to temperature. The significance of the above results in relation to the respiratory functions of the blood is discussed.
The Mechanical Properties of the Cell Surface
Authors: Mitchison J. M. , Swann M. M. 
Published: April 2021

ABSTRACT
A new instrument for measuring the mechanical properties of the cell surface is described. It consists of a micropipette connected to a moveable reservoir of water. The tip of the pipette is brought up to a cell and a bulge sucked out of the surface by lowering the reservoir. A plot of deformation (i.e. degree of bulging) against negative hydrostatic pressure gives a straight line for the sea-urchin egg at all stages. We have called the slope of this line the ‘stiffness ‘of the cell membrane ; it varies with the stage of the egg, the size of the pipette and the speed at which readings are taken. A comparison of the straight-line plots actually obtained with the curves to be expected from pure surface tension or from a thin-walled elastic sphere, leaves no doubt that the cell membrane is not behaving like either of these systems. It is concluded that the membrane is sufficiently thick to resist deformation by virtue of its own rigidity, resembling therefore a tennis ball rather than a rubber balloon or a fluid drop. An analysis of the problem in terms of a thick membrane is mathematically intractable, and is only possible by means of models. Experiments, using a large-scale pipette to suck bulges out of rubber balls, show that over a considerable range of wall thicknesses, the pressure-deformation curves are in fact linear. It is shown that the slope of the pressure-deformation curve or ‘stiffness’ depends on Young’s modulus and the internal pressure. It is not possible to separate these two variables by direct means. A dimensional analysis shows that it is permissible to scale down from model experiments to arrive at Young’s modulus and the internal pressure of the cell. For any given value of ‘stiffness’ there is a series of solutions, with values for the modulus decreasing from a certain figure, and values for the internal pressure increasing from nil. A limit can, however, be set to this series by other measurements.
The Mechanical Properties of the Cell Surface
Authors: Mitchison J. M. , Swann M. M. 
Published: April 2021

ABSTRACT
Measurements were made with the cell elastimeter on the stiffness of the cell membrane in the unfertilized eggs of five species of sea urchin. Young’s modulus varies in the different species between the values of 0·91 × 104 and 2·08 × 104 dynes/c2. Experiments on the change of stiffness in hypo- and hypertonic media indicated that there is probably no internal pressure and no membrane tension in the normal egg. If, however, there is an internal pressure, measurements of the minimum shrinkage of the membrane necessary to produce wrinkling showed that this pressure cannot exceed 95 dynes/cm2. A drop in temperature of 18·5° C. produced an increase of stiffness by a factor of 2·1. These experiments, together with other evidence, suggest that for mechanical purposes the unfertilized sea-urchin egg can be compared to a hollow sphere filled with fluid and surrounded by a solid elastic wall (the membrane or cortex) about 1·5 μ thick and with an elastic modulus about 1·2 × 104 dynes/cm2. This degree of rigidity is sufficient to ensure the maintenance of shape of the egg without the presence of an internal pressure or a tension in the membrane. In everyday terms, the egg therefore resembles a tennis ball or a child’s rubber ball, rather than an inflated balloon or an oil drop in water.
Constituents of Bull Seminal Plasma
Authors: Rothschild Lord , Barnes H. 
Published: April 2021

ABSTRACTThe concentrations of the main inorganic and certain organic constituents of bull seminal plasma have been examined. The average concentrations, in mg./100 ml., were: Sodium and potassium were found to be inversely correlated, r = −0.86 p&lt;0-001. Calcium, chloride, fructose, citrate and total nitrogen were also strongly correlated (p&lt;0-001), in such a way that a knowledge of the concentration of any one of the constituents enabled the average concentration of the other four in the sample to be predicted with considerable accuracy. Sodium, potassium and chloride were estimated by standard chemical methods and with the flame photometer (sodium and potassium) and by electrometric titration (chloride). The applicability of the alternative methods of estimation, which require very small quantities of seminal plasma, has been examined and is discussed. The freezing-point depression, Δ, of bull seminal plasma was-0-533, standard error of mean, 0-005. The A’s of a number of laboratory and field diluents were also examined ; with two exceptions they were found to vary markedly from A for bull seminal plasma.
The Structure of the Yolk of the Hen’s Egg, Investigated by Means of Its Permeability to 82Br
Authors: Maurice D. M. , Fidanza A. 
Published: April 2021

ABSTRACT
82Br was mixed with the white of hen’s eggs maintained at I° C., and its concentration in the yolk and white measured after experimental periods ranging from 5 min. to 200 hr. In some cases the distribution of 82Br in the yolk was determined. From 5 hr. onwards the concentration in the yolk increased at a constant rate reaching on the average 2-5 % of that in the white after 200 hr. This suggested that the penetration was opposed by an external membrane of low permeability (7 × 10−5 cm./hr.). Before 5 hr. the amount of 82Br in the yolk was in excess of that predicted by this mechanism. This did not appear to result from contamination from the white and suggested that there was a layer of yolk external to the resistive external membrane and therefore this was not the vitelline membrane. Even after 100-200 hr. most of the 82Br which had penetrated remained in the superficial layers of the yolk. This showed that there was also a resistance to its penetration in the mass of the yolk itself. The bearing of this evidence on the structure of the yolk is discussed.
Some Tables for the Ionic Composition of Sea Water
Authors: Barnes H. 
Published: April 2021

ABSTRACT
There exists a considerable and increasing interest in the ionic composition of the various tissues and body fluids of a wide variety of animals. During the course of such investigations a knowledge of the ionic composition of the natural environment from which the animals were taken is often required. Routine determinations of salinity are usually made in a Marine Biological Laboratory, but the concept of salinity (or chlorinity), of fundamental importance in oceanography, is somewhat artificial and confusion may be felt by those not familiar with the concept.
The Respiratory Currents in the Tracheal System of the Adult Honey-Bee
Authors: Bailey L. 
Published: April 2021

ABSTRACT
The propodeal spiracles of the honey-bee remain closed in normal air but in air plus CO2 they open as the abdomen contracts, and close as the abdomen expands. The first thoracic spiracles remain open in normal air but in air plus CO2 they nearly close as the abdomen contracts, and open as the abdomen expands. When the bee is in normal air there is a strong tidal flow of air in and out of the first thoracic spiracles, but only a weak and variably directed stream of air through the body. It is deduced that when an active bee is producing metabolic CO2, directed streams of air enter the first thoracic spiracles and the abdominal spiracles and leave via the propodeal spiracles.
The Nerves and Muscles of Medusae
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
It has been shown that a single large bipolar nerve cell in the subumbrella epithelium of Aurellia is necessary and sufficient to conduct the contraction wave across a narrow bridge from one part of the bell to another. This nerve impulse is accompanied by an electrical impulse of the kind usually recorded from the nerves of higher animals. These nerve cells are concerned only with the excitation leading to a contraction wave. There must be other pathways for other transmitted excitation.
The Energetics of Osmotic Regulation in Brackish- and Fresh-Water Animals
Authors: Potts W. T. W. 
Published: April 2021

ABSTRACT
The dynamics of osmoregulation in an ideal semi-permeable animal are discussed. The theoretical minimum osmotic work is evaluated in terms of the surface area of the animal, its permeability and the concentrations of the blood, urine and external medium. It is shown that : (a) The most important means whereby a marine animal entering brackish water can reduce the strain upon its osmoregulatory mechanisms is by reducing the concentration of its blood. (b) In a brackish-water animal the production of urine hypotonic to. the blood has only a very small effect upon the osmotic work. (c) In a fresh-water animal the reduction of the urine concentration to the point at which it is isotonic with the medium can reduce the osmotic work by as much as 90 % ; but even a moderate reduction of the urine concentration, so that the urine is hypotonic to the blood but many times more concentrated than the medium, greatly reduces the osmotic work and is compatible with high osmoregulatory efficiency. These conclusions are discussed with reference to some fresh-water animals.
The Role of Peripheral Nervous System in Colour Changes of Bufo Arenarum Hensel
Authors: Stoppani A. O. M. , Pieroni P. F. , Murray A. J. 
Published: April 2021

ABSTRACT
Stimulation of the peripheral nerves of Bufo arenarum Hensel produces a partial paling of the skin due to concentration of pigment in the intracutaneous melanophores, and dispersion of guanin-granules in the guanophores. This effect is attributed to the liberation in situ of an adrenergic-like substance. Noradrenalin and the cutaneous secretion (which contains adrenalin and active bases) play no part in the blanching of the skin. The nervous system plays a secondary role in the paling of the skin which follows hypophysectomy. There is no evidence that stimulation of the peripheral nervous system is essential for the colour changes of B. arenarum.
Electrophoretic Mobility of Red Cells and Their Ghosts as Observed with Improved Apparatus*
Authors: Ponder Eric , Ponder Ruth V. 
Published: April 2021

ABSTRACTThis paper is concerned with the application of two new techniques, both of which depend essentially on improved instrumentation, to the study of the electrophoretic mobility of red cells and their ghosts. The first technique has been developed to overcome difficulties which are encountered in the measurement of the mobility of ghosts. If the ghosts are substantially haemoglobinized, they can be seen, although with some difficulty, with the ordinary microscope and their mobility can be measured in an electrophoresis cell such as that described by Abramson (1934); if they are relatively Hb-free, on the other hand, they are almost invisible under the ordinary microscope, and can be seen satisfactorily only with phase contrast. The great majority of existing measurements of the mobility of ghosts, accordingly, are measurements of the mobility of ghosts which contain relatively large amounts of Hb. The new vertical cell to be described uses phase-contrast optics, and is fitted with removable electrodes which have several advantages over those usually employed. The second technique is the result of the observation that the Antweiler electrophoresis apparatus with a Philpot-Svensson attachment, although designed for the separation and observation of the mobilities of protein fractions, can also be used for measuring the relative mobilities of red cells and their ghosts.
An Investigation of the ‘Chronometer’ Factor in Bird Navigation
Authors: Matthews G. V. T. 
Published: April 2021

ABSTRACT
An investigation was made of that part of the sun navigation hypothesis which proposes that birds detect longitude displacement by comparing home time (provided by an internal ‘chronometer’) with local time (estimated from the highest point of the sun arc). Shearwaters were exposed for 4 days, and pigeons for ten days, to an artificial day 3 hr. in advance of normal. This did not result in any confusion of their orientation when released to the east. More drastic treatment was then used, pigeons being subjected to 4–5 days of irregular light/dark sequences, followed by 5–11 days of regular sequences, advanced or retarded with respect to normal. In tests from the west (2), east and north after this treatment, the ‘chronometers ‘had apparently been affected and the birds showed a definite tendency to fly in the predicted false direction—east after an advanced day, west after a retarded one. Variations in the time-in-sight, and in the proportion of the more rapid returns supported the conclusions drawn from the orientation data. In a minority (25 %) of the birds, the evidence suggests that the ‘chronometers ‘were not affected. It is concluded that these new results, taken with those produced previously, strongly support the suggestion that a form of complete, bico-ordinate sun navigation is used by birds.
The Cuticular Waterproofing Mechanism of the Worker Honey-Bee
Authors: Glynne Jones G. D. 
Published: April 2021

ABSTRACT
It is now widely accepted, following the work of Alexander, Kitchener and Briscoe (1944 a–c), Wigglesworth (1944, 1945) and Beament (1945), that the thin layer of lipoid material which is present on or near the outer surface of insect cuticle serves to restrict the evaporation of water from the animal. Existing knowledge of the nature of this waterproofing layer has been built up from observations on the effect of dusts, heat, detergents and organic solvents on the rate of evaporation from intact cuticle and also from a study of the changes in permeability of natural and artificial membranes when coated with thin layers of lipoid material.