bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Absorption and Accumulation of Solutes By Living Plant Cells
Authors: Steward F. C. , Berry W. E. 
Published: April 2021

ABSTRACT
Discs cut from plant storage organs have long been favourite material for experiments upon salt absorption. A recent series of papers (Steward, 1932 a–c, 1933 ; Steward, Wright and Berry, 1932) which refers especially to potato tissue indicates that in the past the attention directed to the respiration of these tissues was far too scanty. With the development of an adequate technique (Steward, 1932 b) the general principles operating in the case of potato tissue became increasingly apparent, and the occasion thus arose to extend the investigations to other storage organs. A survey of several storage organs (Berry and Steward, 1934) revealed that discs cut from artichoke tubers combined a conspicuous ability to absorb the salt studied (KBr) with a characteristic respiratory behaviour which presented features somewhat different from those of potato. The present paper records an attempt to ascertain whether the observed behaviour in respiration is reflected in salt absorption in the manner anticipated and to determine further details of the absorption process, with particular reference to potassium bromide and artichoke tissue. A matter which received some special attention was to ascertain whether the absorbed salt replaces ions already within the cell, or accumulates, against a concentration gradient, in the vacuole where it exists in true solution without displacing other ions. Since they were obtained, the results here presented have gained added interest in the light of the results published by Briggs and Petrie (1931) and, more particularly, in view of a theoretical interpretation of absorption by cells (Briggs, 1932) based upon ionic exchange.
The Function of the Antennae inRhodnius Prolixus(Hemiptera) and the Mechanism of Orientation to the Host
Authors: Wigglesworth V. B. , Gillett J. D. 
Published: April 2021

ABSTRACTAnyone who has handled the blood-sucking bugs, Triatoma or Rhodnius, must have observed that they are often attracted to the sides of their jars at places where these have been warmed by recent handling, and that they will probe such spots vigorously with the proboscis. This behaviour suggests that they are attracted to their host mainly by warmth1—a belief which is supported by the recent observations of Rivnay (1932) on the bed bug (Cimex) and of Hase (1932) on various Triatomidae. Further, the movements of the antennae, which precede the location of the host, suggest that these carry the sense organs concerned ; and we were led to undertake the present work because it seemed possible that Rhodnius might prove a favourable subject in which to study both the function of the antennae, and the mechanism by which they secure the orientation of the insect in relation to its host. More particularly we hoped to define this mechanism in terms of the current theories of orientation (Loeb, 1918; Kühn, 1919; Fraenkel, 1931).
Observations on the Fatty Constituents of Marine Plankton
Authors: Drummond J. C. , Gunther E. R. 
Published: April 2021

ABSTRACT
In view of the relations which are believed to exist between the vitamin content of the diet and that of the fats stored in an animal’s body it is of considerable interest to examine the oils separated from phytoplankton and zooplankton respectively. The isolation of the oils and the results of their general chemical examination are described in a preceding paper (Collin, 1934).
Experiments on Embryonic Induction
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
It is shown that the ectoderm of the area opaca of chick embryos of the primitive streak stage can react to primitive streak grafts by the formation of an induced neural plate. The conclusion is drawn that the competence to form neural plate is not conferred on ectoderm by the gut endoderm, which determines the formation of the primitive streak.
Experiments On Embryonic Induction
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
The work of Waddington and Waterman (1933) has shown that it is possible to cultivate young rabbit embryos in vitro, using the normal watch-glass technique and a medium composed of chicken embryo extract and either chick or rabbit plasma. Micro-surgical operations can be performed on such embryos before they are explanted into culture, and the mutual interactions of the various embryonic rudiments can be investigated in this way. It may eventually be possible to obtain as complete an account of the developmental mechanics of the mammalian embryo as Spemann and his school have provided in the Amphibia, but it is probable that operations on the mammalian embryo will always be attended with considerable difficulty. Apart from the laboriousness of the tissue culture technique with its concomitant necessity for absolute sterility, the rabbit embryo, if not every mammalian embryo, is very difficult to handle owing to its transparency, toughness and stickiness. The transparency of the blastocyst and embryonic shield in the primitive streak stage makes it difficult to distinguish exactly the various embryonic organs ; the toughness of the tissue hinders neat cutting and operating ; while the stickiness of the cells is probably the most annoying characteristic of all, since it results in any fragment of tissue, which may for example be intended for a graft, adhering to the operating knives with such tenacity that it frequently becomes entirely macerated during the attempts made to free it.
On the Digestion of Wood by Insects
Authors: Mansour K. , Mansour-Bek J. J. 
Published: April 2021

ABSTRACTThe true wood-feeding insects do not depend on micro-organisms for the digestion of wood. Such insects are of two types: Without cellulose-breaking enzymes. Insects of this type derive the necessary carbohydrates from the soluble sugars and starch in the wood they live on, and consequently such insects can only live in kinds of wood comparatively rich in these substances. With cellulose-breaking enzymes. Insects of this type can utilise the cellulose of the wood through the activity of their own secretions. They therefore can live on woods very poor in the simpler carbohydrates. Wood-eating insects with free-living intestinal micro-organisms (such as the termites and the Lamellicorn larvae) use the micro-organisms as direct food and derive no digestive help from them. Insects of this type are better referred to as micro-organism feeding.
On The Relation of the Thyroid Gland to Metamorphosis in the Lamprey
Authors: Horton Frances M. 
Published: April 2021

ABSTRACT
Ammocoetes were treated with iodine, potassium iodide, iodoform and thyroid extract solutions. No metamorphosis was induced. Injections into ammocoetes of iodoform and of thyroid extract were made, without any metamorphic changes appearing. Lamprey, ammocoete, and ox thyroids were grafted into tadpoles. Lamprey and ox thyroid were equally active in accelerating metamorphosis, but the ammocoete gland has no such effect. The glands of sixty ammocoetes were analysed for iodine. They contained none. The effect of iodine and thyroid on ammocoete respiration was tested. In no case was the oxygen consumption increased. It is concluded that the thyroid gland has no significance in the metamorphosis of the lamprey.
The Effect of Suckling on the Duration of Pregnancy in the Rat (Wistar Albino)
Authors: Hain A. M. 
Published: April 2021

ABSTRACT
It is an established fact that in the mouse and rat ovulation normally takes place between 12 and 32 hours after parturition (Long and Evans, 1922). Only rarely, however, does a pregnancy result from a mating at this time if the mother is suckling a litter (Kirkham, 1916), and in those instances where a second pregnancy does ensue it is of longer duration than is the case in the normal non-suckling animal. Daniel (1910) was of the opinion that an exact relationship existed between the number of young suckled and the extent by which gestation was prolonged. The absence of any such correlation was demonstrated by Kirkham (1916), who also investigated the cause of the prolongation of pregnancy in such cases. This was found to be due to a delay in implantation of the ova released at the post-partum ovulation, a delay which he ascribed to the inhibitory action of the mammary glands upon the uterus; he recognised that this activity was modified by the metabolic idiosyncrasies of the individual.
Notes on Ovulation and Fertilisation in the Ferret
Authors: Hammond J. , Walton A. 
Published: April 2021

ABSTRACT
The ferret ovulates normally about 30 hours after coitus. The average duration of coitus is about 2 hours but varies from 14 hour to 3 hours. There was no evidence that short copulations were less fertile than long ones. For 36 hours after coitus the vulva remains turgid, but becomes flaccid by about 60 hours after coitus, presumably from absence of oestrin. Spermatozoa reach the upper part of the uterus within about 3 hours after coitus, but during this time do not reach the ovarian capsule. Spermatozoa were found in the ovarian capsule 6 hours after coitus. No spermatozoa were found in the ovarian capsule or uterus 10 days after coitus. An attempt to determine the possible duration of fertilising capacity of the spermatozoa in the female tract was made, but no conclusive results were obtained owing to the difficulty of performing artificial insemination in the ferret. In the ferret the ovum remains capable of fertilisation for not more than 30 hours after ovulation. From 18 to 30 hours after ovulation only a small proportion of the ova remain capable of fertilisation, and small litters are produced from matings made at this time.
The Water Relations of Snails and Slugs
Authors: Howes N. H. , Wells G. P. 
Published: April 2021

ABSTRACT
In the first paper of this series (Howes and Wells, 1934), we showed that active specimens of the edible snail (Helix pomatia) continually undergo considerable fluctuations in weight, due to changes in their water content, even in environments which do not greatly vary in physical properties. The following experiments were performed in order to find out whether similar phenomena occur in slugs. Most of the experiments were done on Arion ater, but specimens of Limax flavus were also studied. The results obtained on the two species will be described separately and then discussed together.
Osmotic Regulation in Gunda Ulvae
Authors: Beadle L. C. 
Published: April 2021

ABSTRACT
The triclad turbellarian Gunda ulvae in its normal habitat is daily subjected both to sea water and to pure stream water. Under experimental conditions it can live permanently in any concentration of sea water down to 5 per cent. It is thus able to maintain a relatively constant internal against a rapidly changing external environment. The manner in which this is done is suggested by the results of the above experiments, from which it is concluded that the following is the course of events when the animal is transferred from pure to dilute sea water (e.g. 10 per cent.): (a)An initial inflow of water through the ectoderm into the parenchyma which causes swelling and a temporary lowering of activity.(b)This water is taken up by the gut cells in the form of intracellular vacuoles, a process which entails expenditure of energy and can be inhibited by cyanide. The parenchyma is thus restored to its original condition and full activity is recovered.(c)After the initial inflow of water the animal begins to set up a resistance, which appears to be effected by a decrease of permeability to water of the ectodermal membrane.(d)This resistance is maintained and the gut cells remain vacuolated so long as the animal is kept in dilute sea water. The excretory (water-vascular) system plays no obvious part in this mechanism. Distinction must be drawn between the ultimate impermeability of the ectoderm considered as a membrane and the osmotic resistance of the individual cells of this layer and of the other tissues. The permeability of the ectodermal membrane can be reversibly increased by calcium deficiency, but the osmotic resistance of its individual cells cannot be broken down by these means. This can be brought about by decreasing the osmotic pressure of the water to that of 2 per cent, sea water. Under these conditions the presence of calcium may retard but does not prevent the final swelling and disintegration of the cells, a process which is irreversible. It is suggested that both vacuole formation by the gut cells and the osmotic resistance set up by the individual cells of the other tissues are active processes entailing expenditure of energy, whereas the resistance of the ectodermal membrane to inflow of water into the parenchyma is a passive impermeability.
The Function of the Antennae in Rhodnius Prolixus: Confirmatory Experiments
Authors: Wigglesworth V. B. , Gillett J. D. 
Published: April 2021

ABSTRACT
The conclusion, previously arrived at, that Rhodnius prolixus responds to the gradient of air temperature around the source of stimulus, and not to radiant heat, was based on false premises; but this conclusion has now been confirmed by further experiments.
The Effect of Irradiation With Different Wave-Lengths on the Oestrous Cycle of the Ferret, With Remarks on the Factors Controlling Sexual Periodicity
Authors: Marshall F. H. A. , Bowden F. P. 
Published: April 2021

ABSTRACTThe ferret normally has a well-marked breeding season extending from about the middle of March until July or August, March 2nd being the earliest date in our experience for a normal ferret to come “on heat.” Oestrus in the non-occurrence of pregnancy or pseudo-pregnancy lasts a very long time and has been known to persist for 17 weeks. The condition is particularly easy to detect owing to the enormous swelling of the vulva which may be fifty times its anoestrous size. After ovulation which depends upon coitus the vulval swelling subsides as oestrus comes to an end. Pregnancy lasts about 42 days and there can be two gestation periods in the season (Marshall, 1904; Hammond and Marshall, 1930). The polecat in the wild state has a breeding season at approximately the same time as that of the ferret in captivity (Millais, 1905).
Growth and Ion-Specificity of Excitability in Regenerating Cockroach Giant Interneurones
Authors: Leech C. A. , Treherne J. E. 
Published: April 2021

ABSTRACT
The effects of lesions on cockroach giant interneurones (GIs) were studied to investigate the transient, Ca-dependent, action potentials which have been reported to appear near the tips of regenerating’GIs (Meiri, Spira & Parnas, 1981). We were unable to repeat these observations.
Ligation of connectives, before cutting, delayed the degenerative changes in segments of GIs that were separated from their cell bodies. The shortterm injury response (which was normally observed on cutting while recording close to the site of lesion) was not recorded when the axon was ligated.
The effect of cutting GIs at different distances from their cell bodies was also investigated. There was no apparent relation between the response of GIs to a lesion and the site of the lesion.
Sprouting of GIs was observed both at the tip of the axon and also at sites some distance from the lesion. No changes of the cell body or its dendritic tree in the terminal ganglion were seen but sprouting was observed in other ganglia.
A New Method Measuring Leg Position of Walking Crustaceans Shows that Motor Output During Return Stroke Depends Upon Load
Authors: Cruse H. , Müller U. 
Published: April 2021

ABSTRACT
The basic movement of a walking leg consists of two parts, the power stroke (stance phase) and the return stroke (swing phase). The movement of a leg during the power stroke is determined not only by the sensory-neural system of the leg itself but also by the movement of the other supporting legs because of their mechanical coupling. In contrast the movement during the return stroke is under the sole control of the sensory-neural system of the leg itself. Therefore observation of the return stroke movement allows a more direct view of the motor output from the centre controlling the movement of the leg. Motor output can be recorded by electrophysiological methods. However, quantitative interpretation of these results is often difficult as the transformation of the recorded spikes (often from several superimposed motor units) to force is usually unknown. Whereas motor output during the power stroke clearly depends on walking speed and on load, some studies have found return stroke duration to be dependent upon walking speed, others found no such dependence (for reviews see Clarac, 1981; Evoy & Ayers, 1982). A solution to this discrepancy has been proposed on the basis of a model which assumes that load is an essential parameter affecting the movement of the individual walking leg (Cruse, 1983). A central assumption in this model is that motor output during both power stroke and return stroke is increased when the animal walks under load. It follows from this assumption that an increase in the load should lead to faster return stroke movements and, for constant leg amplitudes, to shorter return stroke durations. As mentioned above this prediction can be easily tested for the return stroke. Therefore, we developed a simple method to measure return and power stroke durations and step amplitude for a decapod walking under water.
Oxygen Consumption in Swimming Salps (Tunicata: Thaliacea)
Authors: Trueman E. R. , Bone Q. , Braconnot J-C. 
Published: April 2021

ABSTRACT
The pelagic salps swim in a regular rhythmic manner, by contracting their muscle bands and so emitting propulsive jets of water from the tubular body. Since they will continue to swim when confined in small chambers in which their oxygen consumption can be measured whilst their activity is monitored, it is possible to make direct estimates of the energetic cost of locomotion, and to compare these with estimates derived from the hydrodynamics of the process (Bone & Trueman, 1983). We show here that salp locomotion is an economical process, and that respirometric and hydrodynamic estimates of the energy expended are in good agreement.
Calcium Metabolism in Embryos of the Oviparous Snake Coluber Constrictor
Authors: Packard Mary J. , Packard Gary C. , Gutzke William H. N. 
Published: April 2021

ABSTRACT
Total calcium in embryos of an oviparous, colubrid snake (Coluber constrictor L.) rises rapidly during the last half of incubation as the embryos increase in size. Although most of this calcium is drawn from stores in the yolk, hatchlings contain more calcium than was present in yolk of eggs at oviposition. Because shells from eggs incubated to hatching contain less calcium than do shells from freshly-laid eggs, the extra calcium appears to be drawn from the eggshell. Indeed, approximately 20% of the calcium required for development in this snake is obtained from the eggshell, with the remainder coming from the yolk. Thus, embryos of oviparous snakes, like embryonic chelonians, crocodilians and birds, withdraw calcium from their eggshells and do not rely exclusively on calcium supplied in their yolk for support of growth and development.
Urine Formation in the Lamellibranchs: Evidence for Ultrafiltration and Quantitative Description
Authors: Hevert F. 
Published: April 2021

ABSTRACT
Physical and chemical parameters were measured in the Japanese oyster Crassostrea gigas to investigate whether the first step of urine formation in the lamellibranchs could be an ultrafiltration and to give a quantitative description. The effective filtration pressure was not constant, but a function of time, oscillating between 31·7mmH2O and −3·8mmH2O. During the filtration, a separation of proteins took place: the protein concentration in the haemolymph was 17μmoll−1 and the average molecular weight was 141000. In the filtrate, the protein concentration was 2μmoll−1 and the average molecular weight was 45 000. The marker substance inulin, applied via the gills, appeared successively within the haemolymph and the pericardial fluid. These findings establish the idea that the pericardial fluid is formed by ultrafiltration from the haemolymph. The rate of filtration was found to be 0·4μlg−1 min−1 by quantitative analysis of the transport of the inulin. The coefficient of filtration was 4·5× 10−6mls−1cm−2mmHg−1.
Neurohormonal Modulation of the Cardiac Outflow Through the Cardioarterial Valve in the Lobster
Authors: Kuramoto Taketeru , Ebara Arinobu 
Published: April 2021

ABSTRACT
Systolic pressure in the abdominal artery of the lobster Panulirus japonicus (Von Siebold) was decreased by contraction of the cardioarterial valve located at the posterior exit of the heart. Crustacean neurohormones, octopamine and proctolin, induced rhythmic contractions or contracture of the posterior valve but serotonin did not induce valve contracture. Systolic pressure in the posterior artery was reduced when the anterior cardioarterial valves contracted at the same time as the posterior valve. Proctolin caused the anterior and posterior valves to contract. Octopamine caused only the posterior valve to contract and often caused the anterior valves to relax. Proctolin induced depolarizing responses while serotonin often induced hyperpolarizing responses in muscle cells of the anterior and posterior valves. Octopamine hyperpolarized the resting membrane potential of muscle cells in the anterior valves and depolarized the membrane potential in the posterior valve. In some intracellular recordings from the valve muscle cells, slow action potentials followed by a plateau were produced on slow sustained depolarization induced by proctolin or octopamine. The action potential was followed by a large contraction of the valve. Contracture of the valve was associated with a large sustained depolarization in single muscle cells of the valve.
Hormonal control of muscle atrophy and degeneration in the moth Antheraea polyphemus
Authors: Schwartz L. M. , Truman J. W. 
Published: April 2021

ABSTRACT
The intersegmental muscles of the giant silkmoth Antheraea polyphemus (Cramer) can undergo two forms of degenerative changes: a wasting atrophy that lasts about 6 days or rapid dissolution that is completed within 30 h. Muscle atrophy is induced by a dramatic decline in the endogenous titres of the steroid moulting hormone 20-hydroxyecdysone. 20-Hydroxyecdysone appears to act as a trophic factor for the muscles as infusion or injection of this steroid blocks further atrophy of the muscle. The normal decline of 20-hydroxyecdysone also allows the muscles to become competent to respond to the peptide eclosion hormone. Eclosion hormone is then released and acts directly on these muscles to induce rapid cell death which is morphologically and physiologically distinct from steroid-regulated atrophy.