bluuebunny/crossref_metadata_2025 huggingface dataset:
The Retention of Salt and the Regulation of the Non-Protein Nitrogen Fraction in the Blood of the Aquatic Larva, Sialis Lutaria
Authors: Beadle L. C. , Shaw J.
Published: April 2021

As in the blood of other insects, chloride forms only a small proportion of the total dissolved substances in the blood of Sialis lutaria larvae. (Chloride 0·15-0·35% NaCl, osmotic pressure 0·80-1·10% NaCl.) Only after more than 5 weeks of starvation in distilled or tap water was the blood chloride reduced to below 0·10% NaCl. With a few days’ treatment in 1.0% NaCl it could be increased to 0·5% or higher. The movements of chloride induced in this way were shown to occur through the external cuticle whose permeability to ions is thus very low. There is no mechanism for the active uptake of ions from the external water, and the resistance to several weeks of starvation in glass-distilled water must be attributed solely to the very low permeability of the cuticle. A large proportion of the non-chloride fraction of the total osmotic pressure is non-protein nitrogen, which is presumably amino-acid. Large and rapid changes in blood chloride were induced by repeated blood extractions which were followed by restoration of most or all of the blood volume by the uptake of water. There was no corresponding alteration in the total osmotic pressure. The concentration of non-protein nitrogen in the blood changes in such a way that the total osmotic pressure is not seriously affected by considerable dilution or concentration of the salts as indicated by chloride, which can be halved or doubled. Estimations of protein nitrogen have suggested the possibility that changes in the non-protein nitrogen are made at the expense of the blood protein. The mean normal protein nitrogen of the blood is approximately the same as that of mammals. But after 6 weeks of starvation it was reduced to about one-twentieth of the original, and in some cases to practically nil without apparent effect on the health of the larva. The initial level of non-protein nitrogen was, however, maintained throughout. These results suggest that a compensatory regulation of the blood aminoacids is an important component of the osmo-regulatory mechanism.
Osmotic Regulation in Mosquito Larvae
Authors: Ramsay J. A.
Published: April 2021

The processes of osmotic regulation in the larvae of Aedes aegypti and of A. detritus have been studied by determination of the freezing-point of samples of fluid collected from different parts of the gut. In A. aegypti, kept in fresh water (its normal environment), the fluid passing down the intestine to the rectum is isotonic with the haemolymph. In the rectum it becomes strongly hypotonic before being eliminated. In A. detritus, kept in sea water (its normal environment), the opposite process is observed, the fluid in the rectum becoming hypertonic to the haemolymph and approximately isotonic with the external medium before being eliminated. In A. detritus, which is able to live in dilute media as well as in sea water, the only two specimens from fresh water available for examination were found to have the rectal fluid hypotonic to the haemolymph. The ability of A. detritus, not possessed by A. aegypti, to produce an hyper-tonic fluid in the rectum is tentatively associated with a region in the anterior part of the rectum and lined with an epithelium distinctly different from that in the remainder of the rectum. This anterior region has not been found in A. aegypti.
A Quantitative Study of the Fragmentation and Haemolysis of Mammalian Red Cells by Heat
Authors: Ponder Eric
Published: April 2021

This paper is concerned with quantitative aspects of the fragmentation of red cells by heat and of the haemolysis which accompanies it. The former process involves a splitting of the cell into fragments which retain, at least in part, some of the properties of the intact cell (ability to swell in hypotonic media, ability to undergo certain shape transformations, etc.; see Ponder, 1949). The latter process results in the formation of ghosts with properties which vary with the haemolytic system ; in some systems, the cell becomes a ghost by an all-or-none process (as in hypotonic systems containing cells in low volume centration, see Parpart, 1931), while in other systems the ghosts are partially haemoglobinized and partially rigid. To describe the phenomena adequately, it is accordingly necessary to consider the transition of the red cell to the ghost as a process which can occur in several ways in addition to the all-or-none escape of Hb and the replacement of the cell by an unsubstantial ghost ; it is all the more important to do this because evidence is accumulating that red cell ghosts in several kinds of haemolytic system possess both shape and rigidity (Ponder, 1942, 1950, Lindemann, 19490a,b).
Inherent Activity in the Sea-Anemone,Metridium Senile(L.)
Authors: Batham E. J. , Pantin C. F. A.
Published: April 2021

A study of the anemone Calliactis parasitica (Pantin, 1935) showed that its most obvious activities are of a peculiarly simple kind. The unstimulated animal seems to be inactive. Activity originates directly as a response to external stimuli. Thus an adverse mechanical stimulus to the passive animal sets up impulses, transmitted by a special ‘through-conduction system’ which in this species activates the marginal sphincter muscle of the oral disk. The closure of this muscle protects the disk. Again, when food touches the tentacles, it is conveyed to the mouth by a series of local responses. In both these instances the activity consists of responses directly related to external stimuli, and the animal behaves as a passive vehicle for the conduction of excitation.
Radiological Observations On the Cardiovascular System in Anguilla Anguilla
Authors: Mott J. C.
Published: April 2021

A description is given of an angiographic method for studying the circulation of blood in the anaesthetized common eel. The valves of the heart are concluded to be competent. The extreme elasticity of the bulbus arteriosus is noted, especially of its anterior end. The circulation time through the gills was 5·6 ±1·9 sec. The circulation in the head is relatively inconspicuous; all the emphasis is on the backward flow of blood from the gills. The circulation times to the viscera are very variable. It appears that the two alternative routes of venous return from the pneumatic duct artery, which are the pneumatic duct vein and the gas gland vein, may both be operating together or either may operate alone.
The Influence of Photoperiod and Temperature on the Induction of Diapause in Diataraxia Oleracea L. (Lepidoptera)
Authors: Way M. J. , Hopkins B. A.
Published: April 2021

The induction of diapause in the pupa of Diataraxia oleracea is influenced by temperature and photoperiod during the larval stage. Low temperatures and short photoperiods tend to induce diapause while high temperatures and long photoperiods tend to prevent diapause.

Diapause is not influenced by light intensity during the larval stage providing the intensity is above a certain minimum.

Diapause is prevented at high temperatures (30-34° C.) if the larvae are reared in darkness.

The photoperiod is operative as a factor influencing diapause only between the beginning of the moulting sleep prior to ecdysis to the last instar and the 3rd-5th day of the last instar. A single diapause-preventing photo-period during the moulting sleep is probably sufficient to prevent diapause.

Diapause in D. oleracea is not influenced by photoperiodically controlled substances in the larval food plant.
Photoperiodicity in the Female Ferret
Authors: Hart D. S.
Published: April 2021

Evidence accumulated during two years’ work and experience in photoperiodicity in ferrets suggests the following conclusions:

Oestrus or anoestrus may be induced by influencing the activity of the pituitary gland; this is effected through a contrast-sensitive mechanism which is stimulated by light:dark sequences. The total daily quantity of light is not the controlling factor. In order to obtain the long-light : short-dark ratio necessary for an oestrusactivating sequence, the ratio should be in the proportion of two parts or more of light to one part darkness and reversed if it is desired to induce a state of anoestrus. Slowly increasing or decreasing planes of light are not an essential part of an oestrus-activating sequence. Because ferrets can be brought into anoestrus quicker than they can be brought into oestrus it is considered that the sexual season curve is more acute when entering anoestrus than when entering oestrus. Doubling the number of light–dark contrast stimuli from one every 24-hour period to two every 24-hour period produced no acceleration of the onset of oestrus nor any indication of a ‘tetanus effect’.
A Bifunctional Single Motor Axon System of a Crustacean Muscle
Authors: Wiersma C. A. G.
Published: April 2021

It is shown that the opener muscle of the hermit crab, Eupagurus bernhardus L., receives a single motor axon. Stimulation of this axon results, when appropriate stimuli are used, in two types of contractions comparable with the fast and slow contractions of doubly motor-innervated crustacean muscles. The theoretical implications of this finding are discussed and a hypothesis offered to explain the mechanism which makes the two contraction types possible. The physiological and anatomical features of the innervation of the four most distal muscles in the legs of Eupagurus are described.
The Function of Haemoglobin in Relation to Filter Feeding in Leaf-Mining Chironomid Larvae
Authors: Walshe Barbara M.
Published: April 2021

Tendipes (= Chironomus) plumosus larvae are unique among species of Tendipes in employing a filter-feeding mechanism for obtaining their food (Walshe, 1947 a). The larva spins a sheet of salivary secretion across the lumen of its tube, after which, by rapid anteroposterior undulations of the body, it irrigates the tube. Plankton or other organic particles in the incoming water current are thereby caught in the salivary net and subsequently eaten. This filter feeding is an energetic process involving glandular activity in spinning the salivary sheet and muscular activity in maintaining a rapid current of water during the filtration of food particles. A study (Walshe, 1950) of the amount of filter feeding at different oxygen concentrations has shown that this is essentially an aerobic process, declining at low oxygen concentrations and absent under anaerobic conditions. Normal larvae are incapable of feeding below about 10% air saturation of the water, while larvae without functional haemoglobin (i.e. after carbon monoxide treatment) cease to feed at 26 % air saturation. Even above this value larvae with carboxyhaemoglobin feed less than normal animals. Thus the haemoglobin, in addition to its established significance as an oxygen carrier at low oxygen pressures (Harnisch, 1936; Ewer, 1942) and during recovery from oxygen lack (Harnisch, 1936; Walshe, 1947b), also plays a part in enabling the larvae to continue an active aerobic feeding process even when little oxygen is available.
Fermentation in the Rumen of the Sheep
Authors: Gray F. V. , Pilgrim A. F.
Published: April 2021

Analyses of the rumen fluid of sheep fed on wheaten hay and on lucerne hay showed that characteristic changes take place in the composition of the mixture of volatile fatty acids in the rumen throughout the day. The changes conform closely to those predicted from the composition of the mixture of fatty acids produced from the same two fodders in vitro. They support the view that propionic acid is relatively more rapidly absorbed than either acetic or butyric acid, and that the fermentation of these fodders in the rumen produces a mixture of the acids in which propionic acid forms a larger proportion than it does in the rumen fluid.
Unit Activity in the Medulla Oblongata of Fishes
Authors: Woldring S. , Dirken M. N. J.
Published: April 2021

Adrian & Buytendijk (1931) have recorded potential waves in respiratory rhythm from the isolated brainstem of the gold-fish. The waves could continue for 1 hr. or more.
Carbonic Anhydrase Activity During Embryonic Development
Authors: Clark A. M.
Published: April 2021

Tissue carbonic anhydrase is usually formed at an early stage in the embryonic development of the chick and mouse. The enzyme does not appear in the blood until a relatively late stage has been reached. In the erythrocytes, it is probable that the enzyme is confined to those cells produced in bone marrow. Evidence is presented to support the theory that towards the end of development, there is a replacement of red cells which contain an embryonic type of haemoglobin but no carbonic anhydrase, by corpuscles in which the enzyme is present together with the adult type of haemoglobin.
The Effect of Pitressin and Pitocin on Water Balance in Bufo Regularis Reuss
Authors: Ewer R. F.
Published: April 2021

In Bufo regularis the injection of either pitressin or pitocin is followed by an increase in the rate of water absorption through the skin, together with a marked decrease in urine flow. The response to pitressin is greater than that to pitocin. The effect of pitocin in increasing water uptake can be attributed to the activity of the 5-10% of the pressor fraction which it contains. A mixture of pitressin and pitocin has the same effect on water balance as a corresponding dose of pituitrin. Pitressin alone has a greater anti-diuretic effect than it has when pitocin is added. Taking into account the antagonistic action of pitocin to pitressin it is possible to account for the anti-diuretic action of pitocin in terms of its pressor fraction content. It is concluded that the pressor fraction is the main factor responsible for both the dermal and the renal components of the water-balance effect produced in B. regularis by injection of mammalian posterior pituitary extracts. This conclusion is discussed in relation to the findings of other workers.
The Technique of Free Skin Grafting in Mammals
Authors: Billingham R. E. , Medawar P. B.
Published: April 2021

Methods are described for the execution of free skin grafts in rabbits, guinea-pigs and mice.

Much of the work in which use has been made of the techniques described above has been generously supported over a period of years by the Department of Plastic Surgery, University of Oxford (Prof. T. Pomfret Kilner, F.R.C.S.).
The Role of Radiation in Photodynamic Action
Authors: Calcutt G.
Published: April 2021

It has been demonstrated that, within certain limits, the radiation of cultures of Paramecium bursaria, which had been kept in the dark, with wave-lengths greater than 3300 A., facilitates a subsequently elicited photodynamic response. A period of darkness following the pre-irradiation allows of a return to the normal condition. The role of radiation in the mechanism of photodynamic action is discussed.

The literature concerned with photodynamic action is surprisingly reticent upon the subject of the role played by the radiation used to induce the effect. It is tacitly assumed that the radiation, plays its part solely via the so-called ‘sensitizing’ agent. The possibility of direct action upon the test material appears to have been ignored. Recently (Calcutt, 1950), evidence has been put forward indicating that wavelengths greater than 3300 A. are effective in influencing the intracellular availability of sulphydryl groups. Additionally, it has been suggested that functional —SH groups are involved in the mechanism of photodynamic action (Calcutt, 1948). Further experimental work has been carried out to endeavour to elucidate this joint question of the role of radiation and —SH groups in photodynamic action.
The Swimbladder and the Vertical Movements of Teleostean Fishes
Authors: Jones F. R. Harden
Published: April 2021

The vertical movements of a teleostean fish may be restricted by the presence of the swimbladder, which will increase or decrease in volume when the fish moves up or down in the water.

It is shown that the restriction that the swimbladder imposes to vertical movements involving a reduction in pressure will depend on physical factors such as

The resistance that the bladder and body wall offer to the expansion of the bladder gas. The percentage volume of the swimbladder and the density change of the fish when it is subjected to a reduction in pressure. The pressure reduction that leads to the rupture of the bladder wall.

A distinction is made between rapid and slow movements. In the former the compensatory ability of the fish must be considered and in the latter the speed with which the fish can accommodate itself to pressure changes.

An equation is derived from which the minimum speed at which a physoclist can migrate from deep to shallow water can be calculated. To solve the equation two factors must be determined experimentally.

Various experiments are described which were made on the perch, Perca fluviatilis, the wrasse, Crenilabrus melops the rockling, Onos mustela and the dragonet, Callio-nymus lyra. The results showed that there was a relation between the relative size of the swimbladder and the change in the density of a fish when it is subjected to a reduction in pressure; that the bladder and body wall of the perch offer little resistance to the expansion of the bladder gas ; and that the danger of the bladder wall rupturing might restrict the extent of rapid movements made by the perch.

Experiments on the restriction that the swimbladder imposes to the rapid and slow vertical movements of the perch will be described in.a following paper.
Studies on the Physiology of Ascaris Lumbricoides
Authors: Hobson A. D. , Stephenson W. , Beadle L. C.
Published: April 2021

Vialli (1923, see Schopfer, 1927), Duval & Courtois (1928) and Schopfer (1924, 1925, 1926, 1927, 1932) have shown by means of freezing-point determinations that the osmotic pressure of the body fluid of Parascaris megalocephala and Ascaris vitulorum is lower than that of their hosts. Schopfer (1932) found that the depression of the freezing point of extracts of whole specimens of A. ovis and A. lumbricoides was in each case less than that of the intestinal fluid of the host. He (1932) also found a similar relationship in the case of Proleptus obtusus, an intestinal parasite of Scyliorhinus caniculus, and Panikkar & Sproston (1941) came to the same conclusion as the result of their work on an unidentified species of Angusticaecum from the tortoise. In free-living land or fresh-water nematodes the body fluid is presumably hypertonic to the environment, and Stephenson’s work (1942) indicates that in Rhabditis terrestris this is, in fact, the case, and that there is an active process of osmotic regulation by means of which this difference in osmotic pressure is maintained.
Studies on the Physiology of Ascaris Lumbricoides
Authors: Hobson A. D. , Stephenson W. , Eden A.
Published: April 2021

For the investigation of many aspects of the physiology of Ascaris lumbricoidis and other parasitic nematodes the provision of a fluid medium in which they can be kept alive and healthy in the laboratory is necessary. This is a matter of considerable difficulty, since the natural environment of such animals contains organic substances which are subject to bacterial action. Consequently, most of the experimental work which has been carried out has been on animals kept in saline solutions to which organic constituents were not added. In view of the fact that balanced salt solutions are usually employed in physiological work, it is somewhat surprising to find that solutions of sodium chloride have been used by many recent workers (see, for example, Hamisch, 1933, 1935; Hoffmann, 1934; Waechter, 1934; Kriiger, 1936, etc.). Dewitz (1899), however, used sea water in the case of an unidentified nematode from the tissues of Scomber scombrus. Some later workers, such as Slater (1925), Adam (1932) and Hirsch & Bretschneider (1937), used Ringer or Tyrode’s solution for Ascaris lumbricoides and Toryu (1934) kept Parascaris equorum in Ringer. Davey (1938), working with adult Ostertagia circumcincta and Fenwick (1939) with larvae of Ascaris lumbricoides, developed, by means of a series of survival experiments, saline media in which the animals could be kept alive in the laboratory for some days. Baldwin (1943) also used a balanced salt solution in which adult A. lumbricoides would survive for as long as 10-11 days, although the worms were undoubtedly unhealthy after the first few days in this medium. Hobson, Stephenson & Beadle (1951 ; and see Hobson, 1948), working with A. lumbricoides, in 1941 used 29% and, later, 30% sea water as a medium. In this, individual specimens have survived in apparently healthy condition for as long as 28 days. Baldwin & Moyle (1947) have used a medium based upon Eden’s analyses (see later in the present paper) of the body fluid of the same species. In this the animals did not five longer than in Bald-win’s original medium (Baldwin, 1943), although they remained more active. The composition of the various media to which reference has been made is given in Table 1.
The Induction of Regeneration in the Hydroid Cordylophora Lacustris
Authors: Moore Janet
Published: April 2021

Beadle & Booth’s work on grafting oral cones into reconstitution masses of Cordylophora lacustris has been repeated, confirmed and extended. Oral cone grafts induce the development from mass tissue of hydranth regions basal to the oral cone, and other regeneration of the mass is inhibited. Except in the most quickly developing material, induced development is significantly faster than ‘spontaneous’ development. Inducing action when grafted to a mass is not peculiar to the oral cone but is a property of all tissue with hydranth differentiation (the tentacular ring, subten-tacular region, hydranth neck and even pieces of tentacle), and of tissue containing the rudiment of hydranth differentiation (the tips of outgrowths developing from masses). Tissue which does not possess hydranth differentiation (unspecialized stem coenosarc and stolon tips) has no inducing activity but is absorbed into the mass without influencing its regeneration. Grafts of basal hydranth regions and outgrowth tips normally regenerate oral cones out of graft tissue, but induction may occur even when no oral cone is regenerated by the graft. Tentacle grafts do not regenerate an oral cone; the oral cone of the induced hydranth develops from mass tissue. Inducing power therefore does not depend upon the regeneration by the graft of an oral cone. Grafts of inverted oral cones or fragments of oral cones may produce induction. That inducing activity does not depend on the size, orientation or completeness of the grafted differentiated tissue further shows that it is the presence of hydranth differentiation in tissue, rather than any other factor, which confers inducing ability. No induction has been produced when an oral cone graft is separated from the host tissue by an agar or a cigarette paper barrier. Direct close contact between the graft and the host appears to be necessary for induction to be produced. Grafts of agar on to which oral cones have previously been squashed, macerated oral cones or killed oral cones do not produce induction. If macerated oral cone tissue becomes reorganized into a small fragment possessing the histological structure of part of an oral cone, induction may then occur. The separated constituents of differentiated tissue do not appear to be capable of producing induction.
A Comparative Study of the Lipids of the Vertebrate Central Nervous System
Authors: McColl J. D. , Rossiter R. J.
Published: April 2021

The concentration of water, cerebroside (glycosphingoside), free and total cholesterol, total phospholipin, monoaminophospholipin (phosphoglyceride) and lecithin (phosphatidyl choline) was determined in the spinal cords of a series of vertebrates including representatives of the cartilaginous and bony fishes, amphibians, reptiles, birds and mammals. From these figures was calculatedthe concentration of ester cholesterol, sphingomyelin (phosphosphingoside) and kephalin. As was previously found for brain, the spinal cords of each of the species studied contained negligibly small concentrations of cholesterol ester. The concentration of each lipid in the spinal cord was very similar for different individuals of the same species, but for different species within the same class the mean concentration of many of the lipids extended over a wide range. The concentration of total cholesterol, sphingolipid and myelin lipid was greater in the spinal cords of mammals than in the spinal cords of the lower vertebrates. Expressed as a percentage of ‘essential lipid‘, the concentration of cerebroside, cholesterol, sphingomyelin, sphingolipid and myelin lipid, but not of lecithin and kephalin, was greater in the spinal cord than in the brain. For the spinal cords of the species studied, the mean concentration of cerebroside expressed as a percentage of ‘essential lipid’ was negatively correlated with the mean concentration of sphingomyelin. The results are discussed in relation to the chemical nature of the lipids of the myelin sheath of a vertebrate nerve fibre.
Observations on the Mechanism of Feeding in the Suctorian Podophrya
Authors: Kitching J. A.
Published: April 2021

Podophrya sp., studied in this work, feeds on various holotrich ciliates. The tips of the tentacles adhere to the prey. Within a few minutes the cilia of the prey in the region where the Podophrya is attached stop beating. The stoppage spreads from here outwards over the surface of the prey. In some cases the surface of the Podophrya becomes wrinkled. The prey is broken down locally in the region of attachment, material from the prey flows up the tentacles into the Podophrya, and the Podophrya gets bigger, any wrinkles that may have formed becoming smoothed out in the process. Wrinkling of the Podophrya is shown by observations and experiments to be due to an expansion or growth of the body surface. This expansion serves to reduce the hydrostatic pressure within the Podophrya, so that feeding may proceed. It is suggested that expansion of the body surface, coupled with a supposed resistance to inward collapse, might provide suction for feeding. Wrinkling of the surface is ascribed to a local collapse which may be supposed to occur when uptake of food material from the prey fails to keep pace with the expansion.
Studies in Diurnal Rhythms
Authors: Cloudsley-Thompson J. L.
Published: April 2021

A composite diurnal locomotory rhythm has been established in the woodlouse Oniscus asellus. This is correlated primarily with alternating light and darkness, and not with fluctuating temperature or humidity.

The intensity of the humidity response of the species is less in darkness than in light, and less still in darkness when the animals have been kept in darkness for some days previously. It increases with desiccation. The response to light is greater, too, in animals which have been kept in darkness for some days, and these tend to remain photo-negative in dry air whereas controls become photo-positive with desiccation. The sensitivity to carbon dioxide is much greater in animals from a culture kept in darkness than it is in controls.

The results obtained are discussed in relation to the nocturnal ecology of the species.
Sympathomimetic Activity in the Isolated Frog’s Heart (Rana Temporaria)
Authors: Smith C. L.
Published: April 2021

In a previous paper (Smith, 1951) the occurrence of various types of relation between temperature and the pulse rate of the isolated frog’s heart was reported. Five main types of curve were observed and their chief features may be briefly summarized as follows. Type A showed an exponential relation between frequency and temperature, and corresponded to the ‘winter’ curve originally described by Barcroft & Izquierdo (1931). Type B was rather similar to A, but instead of the rates lying along an even curve they lay on two straight lines which intersected at about 10° C. Type C showed a linear relation between frequency and temperature over the range investigated and the value of the observed temperature coefficient (Q10) was about 2·5. This form corresponded to the ‘summer’ curve of Barcroft & Izquierdo (1931). Type D was of infrequent occurrence, and in this case the pulse rates for the upper and lower temperatures lay on straight lines of very similar slope, but which had different origins at 7° C. Type E again showed a linear relation between pulse rate and temperature, but in this case the observed temperature coefficient was significantly lower than that found for type C (2·1). It was further shown that pulse rate curves of type B or type D could be produced by treatment of type E hearts with an extract of anterior pituitary gland in the presence of added adrenaline. Type C curves were obtained from type E hearts when they were perfused with Ringer containing anterior pituitary extract, adrenaline and thyroxine. To explain these results it was suggested that there was a synergistic action between an anterior pituitary principle and adrenaline which was inhibited at temperatures below 10° C. Further, as types A, B and C pulse rate curves could be obtained from normal hearts in the absence of external adrenaline, the hypothesis was advanced that the isolated heart was under the influence of an active sympathomimetic substance even when it was being perfused with unmodified Ringer.
Optical Changes in the Membranes of the Sea-Urchin Egg at Fertilization, Mitosis and Cleavage
Authors: Mitchison J. M. , Swann M. M.
Published: April 2021

Changes in birefringence and light scattering of the sea-urchin egg membranes at fertilization, mitosis and cleavage are described and illustrated. There is a close similarity between the changes in the cortex at fertilization and at cleavage. The changes in the cortex at cleavage start at the poles of the cell, and only later spread to the equator.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A.
Published: April 2021

The rate of output of the contractile vacuole of the suctorian Podophrya sp. was found to increase during feeding up to ten times. It decreased at the end of the meal but remained higher than it was before feeding. The extra output of the contractile vacuole during feeding was approximately equal to the decrease in volume of the prey minus the increase in volume of the Podophrya. In a typical meal roughly one-half of the food ingested by Podophrya was accommodated by expansion, and one half by concentration of the food taken in. This concentration was brought about by the action of the contractile vacuole.
The Effects of Posterior Pituitary Extracts on Water Balance in Bufo Carens and Xenopus Laevis, together with some General Considerations of Anuran Water Economy
Authors: Ewer R. F.
Published: April 2021

The effects of pitressin and pitocin on water balance in Bufo carens and Xenopus laevis have been investigated. Bufo carens is most sensitive to pitressin, and shows an increased water uptake together with a well-marked anti-diuretic response. Xenopus reacts equally to the two extracts by an increase in water uptake, but there is no anti-diuresis. The effects of pitressin and pitocin in causing lymph accumulation and resorbtion of fluid from the bladder have been studied in Bufo regularis. Pitressin has the greater effect, and there are indications of seasonal variations in the magnitude of the response. The normal rates of water uptake of B. regularis, B. carens and Xenopus laevis have been measured. The two species of Bufo take up water rapidly, but Xenopus does so much more slowly. After desiccation the water uptake of Bufo regularis increases very considerably. This does not occur in Xenopus. There is a large weight increase after injection of posterior pituitary extracts in Bufo regularis and B. carens, but not in Xenopus laevis. The findings of other workers on the magnitude of the weight increase after posterior pituitary injections are summarized. The results are discussed in relation to the identity of the active principles of the anuran posterior pituitary and to the biological significance of the responses.
Flow Orientation as a Possible Explanation of ‘Wave-Motion’ and ‘Rheotaxis’ of Spermatozoa
Authors: Walton Arthur
Published: April 2021

Flow orientation of spermatozoa in dense suspensions has been demonstrated by optical and electrical methods.

Relaxation time, i.e. the time required for a suspension of elongated cells, which have been orientated by flow, to regain a certain degree of random distribution when flow ceases, has been shown to be closely and inversely related to motility, as measured by impedance change frequency in the suspension.

Flow orientation may provide a physical explanation of ‘wave-motion’ and ‘rheotaxis’ of spermatozoa.

Wave-motion occurs in a suspension of elongate cells which possess progressive motility in the direction of the long axis of the cell. Orientation of the cells may be brought about by ‘short-range order’ or flow. Disorientation may be brought about by streams of orientated cells moving in random directions. In the suspension as a whole an equilibrium will be reached such that the forces tending towards orientation (short-range order or flow) are balanced by forces tending towards disorientation (streaming). In small regions, however, statistical variation in the direction and velocity of the streams set up by sperm movements will produce local disturbance of the equilibrium and turbulence or wave-motion will result.
Various Types of Ghosts Derived from Human Red Cells: Heat Fragmentation and Phase Optics Studies
Authors: Ponder Eric
Published: April 2021

This investigation started with the incidental observation that a slight modification in the method used for preparing ghosts from human red cells results in a remarkable difference in one of the properties of the ghost; more specifically, when ghosts are prepared by the addition of large volumes of water, they are not fragmented by heat unless a certain concentration of salt is present (Ponder, 1951). Extension of these observations, made possible by phase-contrast optics, has led to the idea, already suggested by electron microscope studies, that a large number of kinds of ghost, each with its own characteristic properties, can be prepared from a single kind of red cell. This is a very different idea from the usual one that the ghost is a ‘residue’ which, apart from small differences in chemical composition, is essentially the same whether it is obtained from one kind of red cell or from another.
Parthenogenesis in the Mollusc Paludestrina Jenkinsi
Authors: Robson Guy C.
Published: April 2021

The keeled form of Paludestrina jenkinsi is described and its distribution discussed. The keel is found to be non-heritable through three parthenogenetic generations. The evidence for the (a) environmental and (b) auto-genous origin of the keel is analysed. The result is a presumptive case in favour of the former, though such a keel is not among the structural modifications which have been proved, either by experiment or otherwise, to be produced by environmental factors. The various modifications of the keel show that, if of environmental origin, a more complex structural system is produced than is usual in such cases. It is suggested that, as the keel (or one of its derivatives) is found as a fixed character in another species of the same genus and in allied genera, it is deprived at present of the means of attaining genetic stability in P. jenkinsi.
The Properties of an Intercellular Matrix and Its Relation to Electrolytes
Authors: Gray J.
Published: April 2021

The intercellular matrix of the cells on the gills of Mytilus edulis is readily dispersed by hydroxyl ions. All cations inhibit the action of hydroxyl ions, but the divalent metals are much more powerful than the monovalent metals. All divalent metallic ions except magnesium irreversibly coagulate the matrix at the hydroxyl ion concentration of seawater. This does not occur in the presence of magnesium ions. There is a marked difference between the action of different non-electrolytes, since in the absence of salts the matrix remains stable for a much longer period in sugar, or glycerine, than in urea. Alcohol in certain concentrations has a marked stabilising action in the absence of salts. With pure solutions of different monovalent sodium salts the anions can be arranged in a well-marked series in which the matrix is most readily dispersed in sodium iodide The relationship of the matrix to ions is similar to that between protein systems and ions, when attention is paid to both the electrostatic and lyophilic effect of the ions, and to the fact that the matrix is normally in equilibrium with a solution containing divalent metallic ions — magnesium in particular. The analogy must, however, not be pushed too far. The intercellular matrix of Mytilus cells can only possess a very slight electro-negative charge when in equilibrium with sea-water. If the constitution of the membrane is altered in such a way as to increase this charge, a type of matrix forms in which calcium is an essential constituent. Such a matrix appears to exist in echinoderms and in some other types.
The Spermatozoa of Sterile Bulls
Authors: Hancock J. L.
Published: April 2021

Sterility in certain Friesian bulls is associated with a specific morphological abnormality affecting the acrosomes of their spermatozoa. This abnormality is visible in living spermatozoa and is also visible in fixed spermatozoa when precautions are taken to preserve the morphology of the cell. If such precautions are not taken, and the spermatozoa are subsequently stained by the nigtosin-eosin method, or with Heidenhain’s iron haematoxylin, or when such spermatozoa are examined with the phase-contrast microscope, the abnormality is inconspicuous. These difficulties do not arise when either the Giemsa stain or indian ink is used.
The Central Nervous System and Regeneration in Crustacea
Authors: Needham A. E.
Published: April 2021

The neural influence on the rate of regeneration of a limb in Asellus emanates from the segmental ganglion. It is independent of other centres of the c.n.s. Operations on the animal cause a non-specific retardation of all limbs regenerating immediately afterwards. The immediate cause is probably haemorrhage, since the effect is both systemic and proportional to the severity of injury. This general retardation acts differentially on a series of limbs, in proportion to their normal regeneration-rates. It has been possible to obtain a quantitative measure of this ‘differential inhibition’.
The Influence of Dissolved Oxygen on the Respiratory Movements of Caddis Larvae
Authors: Fox H. Munro , Sidney Jasmine
Published: April 2021

Caddis larvae which bear cases ventilate their gills by undulatory movements of the abdomen. These respiratory movements produce a stream of water flowing out through the posterior opening of the case. In well-aerated water the movements are intermittent, periods of undulation alternating with pauses. In poorly aerated water the pauses become shorter.
Osmotic Relations in Molluscan Contractile Tissues
Authors: Pilgrim R. L. C.
Published: April 2021

The general problem initiating these researches was outlined in the previous paper (Pilgrim, 1953). The following pages describe the action of variations in osmotic pressure of the surrounding fluid on the gill cilia of three lamellibranch species of contrasting ecological distribution. Details of the media used are given in an Appendix to the previous paper.
The Occurrence of Blood Groups in Cats
Authors: Holmes R.
Published: April 2021

Methods are described which have been used to investigate isoagglutination reactions of the blood of cats. Evidence is presented which indicates that cats possess at least three groups. The methods and results of earlier workers which indicated that grouped isoagglutinins did not occur in cats have been criticized.

A genetical system for the cat groups similar to the human ABO system is shown to be untenable.

Two other possible systems similar to the A1A2O, and to the Rh models of humans are suggested and briefly discussed.
Active Transport of Potassium by the Malpighian Tubules of Insects
Authors: Ramsay J. A.
Published: April 2021

The concentrations of sodium and potassium in the haemolymph and in the urine have been measured in eight species of insect. The concentration of potassium in the urine is always greater than in the haemolymph. The concentration of sodium in the urine is generally less than in the haemolymph. In seven of the species the difference of electrical potential across the wall of the tubule has also been measured. In these seven species the results lead to the conclusion that potassium is actively secreted into the tubule. It is very probable that the same is true in the eighth case. It seems likely that the excretion of sodium can be brought about by passive diffusion into the tubule.
Distributed ‘End-Plate Potentials’ of Crustacean Muscle Fibres
Authors: Fatt P. , Katz B.
Published: April 2021

Crustacean muscles are known to produce powerful contractions without propagated action potentials (Wiersma, 1941a; Katz & Kuffler, 1946 ; Katz, 1949). It has been suggested (Wiersma, 1941a) that this type of response is made possible by the presence of nerve endings which are widely distributed along the surface of the muscle fibres. When nerve impulses arrive at the endings, a local depolarization is produced in the muscle fibre and in turn gives rise to contraction. This depolarization will be referred to as ‘end-plate potential’ (e.p.p.) by analogy with the e.p.p. of vertebrate muscle. A sufficiently large e.p.p. initiates a spike potential (Katz & Kuffler, 1946), which serves to strengthen the muscle response and, probably, to level out local inequalities in the fibre rather than to conduct excitation (cf. Fatt & Katz, 1953).
Metabolism of the Black Snake Embryo
Authors: Clark Hugh
Published: April 2021

Very few data exist on the nitrogenous excreta of reptilian embryos. Tomita (1929) indicates a substantial urea excretion by the turtle Chelonia, but no data are available for saurian reptiles. They have been presumed (Fiske & Boyden, 1926) to excrete uric acid because ‘a substance as soluble and diffusible as urea could not possibly replace it (uric acid) as an end product when the organism and its excretions are confined to a closed system, the walls of which are only permeable to matter in the gaseous state’. Needham (1931) estimates that the chick urea concentration would reach 165 mg. % if it excreted only urea, and intimates that such an accumulation in a cleidoic egg would be pathological.
The Diurnal Rhythm of Activity of Mayfly Nymphs
Authors: Harker Janet E.
Published: April 2021

Moon (1940) has shown that nymphs of Ecdyonurus and Baetis move more during the night than the day under natural conditions, and he conjectured some indirect relationship between the stage of development and activity. This investigation has been undertaken as an attempt to discover the range of the diurnal periodicity of movement and the conditioning factors.
The Inorganic Constituents of the Sea-Urchin Egg
Authors: Rothschild Lord , Barnes H.
Published: April 2021

The principal inorganic constituents of the unfertilized egg of Paracentrotus lividus have been analysed by chemical methods. The results of the analyses, in millimoles per kg. of water in the eggs (dry weight of eggs, 24 %; density, 1 ·09), were : The figures in brackets are the concentrations of the same substances in Roscoff sea water, chlorinity 19·37%, in the same units. The total phosphorus content of the eggs was about 2 mg./ml. eggs, somewhat over half of this being acid-soluble phosphorus.
Osmotic and Ionic Regulation in the Isopod Crustacean Ligia Oceanica
Authors: Parry G.
Published: April 2021

Osmotic pressure of the blood of Ligia oceanica, measured by the freezingpoint depression, has a mean value of Δ 2·15 ±0·04° C. (≡ 3·58 % NaCl on weight/ volume basis). Osmotic pressure of Ligia blood is much higher than that of other terrestrial isopods: Oniscussp. Δ1·04° C.; Armadillidiumsp. Δ1·18° C. -, Porcellio sp. Δ1·30° C. or of the fresh-water Asellus sp. Δ0·500 C. The osmotic pressure of the blood increases during the process of moulting, but no subsequent decrease is observed in the 4 days following. Animals kept at low humidities lose water. They may be desiccated without permanent adverse effects until Δblood is 3·48° C. (≡ 5·8% NaCl). Recovery to a normal level takes about 24 hr. in moist conditions. In well-aerated sea water between 50 and 100% concentration, animals survive without much alteration in Δblood. Above and below this range Δblood rises and falls. In animals kept on filter-paper moistened with distilled water Δblood may fall to 1·44° C. (=2’4% NaCl) without permanent adverse effects. Analyses of inorganic ions in the blood show that sodium, potassium and chloride are all higher in concentration than in sea water; calcium is much more concentrated ; and magnesium and sulphate much reduced.
Active Transport of Water by the Malpighian Tubules of the Stick Insect, Dixippus Morosus (Orthoptera, Phasmidae)
Authors: Ramsay J. A.
Published: April 2021

Single Malpighian tubules of the stick insect have been studied as preparations isolated in drops of haemolymph under liquid paraffin. Measurements of osmotic pressure have been made on haemolymph and urine. The urine is more or less isotonic with the haemolymph over a wide (45-145%) range of osmotic pressure. But in a majority of cases the urine is slightly but significantly hypotonic to the haemolymph. From these and other observations it is concluded that water must be actively transported across the wall of the tubule. The implications of this conclusion are discussed. The normal rate of urine production is of the order of 0.07 × 10-3 cu.mm./sq.mm./min. The rate increases with increasing dilution of the haemolymph and vice versa. Urine production normally ceases, probably as a result of distension of the tubule, when the pressure in the lumen rises to about 20 cm. H2O.
The Influence of Water and Light and the Pituitary Upon the Pigmentary System of the Common Toad (Bufo Bufo Bufo)
Authors: Rowlands Anne
Published: April 2021

Bufo bufo bufo shows no melanophore response to moisture. The severance of the optic nerve or the removal of the eyes causes a cessation of secondary responses to illuminated background. Some melanophore activity remains. The cauterization of the optic chiasma or the infundibular stalk brings about the permanent expansion of the melanophores. Hypophysectomy, and cauterization with hypophysectomy, both produce permanent contraction of the melanophores. The implications of these results in relation to chromatic control are discussed.
The Influence of Dissolved Oxygen Concentration on the Toxicity of Potassium Cyanide to Rainbow Trout
Authors: Downing Kathleen M.
Published: April 2021

Survival times of rainbow trout in concentrations of potassium cyanide in the range 0.105-0.155 p.p.m. cyanide increased with increase in dissolved oxygen concentration between 10 and 100 % of air saturation value, the effect being most marked with the lowest concentration of cyanide. The rate of increase of survival time with increasing concentration of oxygen did not appear to fall off as air saturation value was approached. The distributions of survival times which had median values of 3.3 min. or less were approximately normal, and those with median values of 13.0 min. or more were approximately log-normal.
The Activity of Slugs
Authors: Dainton Barbara H.
Published: April 2021

Activity in slugs has been shown to occur in response to certain temperature changes (Dainton, 1954). In the description of these responses it was stated that light had no effect provided 1 hr. was allowed for light-adaptation. The experiments which led to this conclusion are described in this paper. Light initially stimulates activity in dark-adapted animals, but the response is short-lived, adaptation being complete within an hour. Preliminary observations indicated that activity was also affected by air currents, and responses to this form of stimulation are also described below.