bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Tolerance and Acclimatization in Drosophila Subobscura
Authors: Smith J. Maynard
Published: April 2021

The times for which adult Drosophila subobscura survived at high temperatures in dry and in saturated air were measured at different temperatures, over a range of survival times from 20 to 400 min. There is a linear relationship between the logarithm of the survival time and the temperature in both cases, the values of Q10 being approximately 350 in dry air and 10,000 in wet air. Survival times in dry air were increased in individuals previously kept at a high temperature (25° C.). Two kinds of acclimatization can take place, a long-lasting ‘developmental acclimatization’ in individuals kept at 25° C. during preadult life, and a transitory ‘physiological acclimatization’ in adults kept at 25° C. Survival times in saturated air were only slightly increased in individuals previously kept at 25° C. Although physiological acclimatization increased the resistance of flies to desiccation rather than to high temperature as such, it is nevertheless a response to previous exposure to high temperatures, and not to high saturation deficiencies. The reversibility of changes occurring at high temperatures was studied by exposing individuals for 50 min. to a temperature which would kill them in 100 min. and then retesting them after an intervening period at 20° C. Flies exposed to dry air recovered fully if they were allowed to drink ; flies exposed to saturated air recovered in 3 hr. at 20° C., but complete recovery in this period required the presence of food and water.
The Respiration of Helix Pomatia, A Balance Sheet
Authors: Kerkut G. A. , Laverack M. S.
Published: April 2021

The respiratory rates of tissue slices from the various organs of Helix pomatia have been determined. The internal organs such as the brain and liver show a higher QO2 when immersed in Baldwin’s phosphate solution. The external organs such as the mantle and collar show a higher QO2 when immersed in Krebs-Ringer solution. The brain has the highest QO2; it is followed in order by the liver, gut, mantle, kidney, columella muscle, female duct, albuminous gland, body wall, dart sac and foot. The rate of respiration of a series of intact snails has been determined. The organs from each of these snails were removed, dried and weighed. From the respiration rates determined in the early part of the paper, a balance sheet was drawn up for each snail. The summated tissue respiration is compared with the respiration of the intact animal. In three out of the twelve cases cited there was good agreement between the summated tissue respiration and the respiration of the whole animal. In the nine other cases the respiration of the whole animal was 40-70% below the summated tissue respiration. This would indicate the possibility that the snail has some means of controlling the rate at which the tissues respire in the intact animal.
A Note on the Oxygen Requirements of Xenopus Laevis
Authors: De Graaf A. R.
Published: April 2021

It is shown that survival in Xenopus is not dependent upon the presence in the blood of a functional respiratory pigment. The implications of this finding are discussed in relation to the possibility of selective distribution of the blood to different parts of the body.
The Influence of Pigment Migration on Vision of Higher Crustacea
Authors: De Bruin G. H. P. , Crisp D. J.
Published: April 2021

Exner believed that the movement of the distal pigment during light-adaptation improved the visual acuity of the superposition eye. This hypothesis was tested by measurement of the visual acuity of Leander serratus, Pandalus montagui and Praunus flexuosus under different conditions. When a dark-adapted animal is placed in the light the proximal pigment migrates into the light-adapted position more rapidly than the distal pigment. The distal pigment, but not the proximal pigment, undergoes diurnal rhythm and tends to migrate into the dark-adapted position at night, even when the animal is illuminated. The visual acuity may therefore be tested when the distal pigment is still in the dark-adapted position and the proximal pigment in the light-adapted position. No difference in visual acuity could be detected as a result of changes in the position of the distal pigment. Visual acuity increases and light sensitivity decreases when the dark proximal pigment migrates over the reflecting (tapetal) layer. Eupagurus bemhardus, which lacks the typical tapetum, shows no detectable change in visual acuity or sensitivity after being kept in the dark. These experiments do not support Exner’s view of the function of the distal pigment. They indicate that visual acuity is improved by the presence of the dark proximal pigment at the base of the proximal retinulae, probably because this pigment reduces stray reflexions from the back of the eye (halation). It is suggested that since the crystalline cones and crystalline tracts form optically continuous strands with a higher refractive index than that of the surrounding medium they may act as wave guides. If so they would retain light entering the corneal surface from sources close to the axis of the ommatidium, and so concentrate it on the rhabdomes and adjacent retinulae.
Effect of Anaesthetics on Workers of the Ant Myrmica
Authors: Weir J. S.
Published: April 2021

Experiments have shown that ether, nitrous oxide, and carbon dioxide all have significant and different post-anaesthesial physiological effects on workers of Myrmica. They reduce longevity and all except nitrous oxide reduce oviposition. Nitrous oxide causes abnormally early accumulation of an egg mass. The effects of these three anaesthetics can be distinguished from one another, and from the effects of nitrogen anaesthesia (presumed anoxia). Their effects may occur together with, and in addition to, those attributable to anoxia. The effects of the anaesthetics on Myrmica longevity appear to be due to the direct physiological action of the anaesthetic and do not operate indirectly via ethological change as supposed in previous work on Apis. These results are discussed in relation to previous work including the concept of artificial ageing which is shown to be untenable in this instance.
Glucose Absorption in the Cockroach
Authors: Treherne J. E.
Published: April 2021

The absorption of glucose from the gut of the cockroach has been studied by feeding starved insects with 14C-labelled glucose together with a dye, Amaranth. This dye is not absorbed from the lumen of the intestine and the net percentage glucose absorption has been calculated from the glucose/dye ratio in the various parts of the intestine. Glucose absorption is largely confined to the mid-gut caeca. The rate of crop emptying, which is an exponential function of time, is related to glucose concentration, so that the amount of fluid leaving the crop decreases with increasing concentration. This effect is determined by the osmotic pressure of the ingested fluid. The total glucose absorption shows a linear relation with crop emptying, suggesting that crop emptying is the limiting process in glucose absorption in the cockroach.
The Blood Volumes of Some Representative Molluscs*
Authors: Martin A. W. , Harrison F. M. , Huston M. J. , Stewart D. M.
Published: April 2021

The reports of measurements of the blood volume of molluscs found in the literature are few in number and represent, in most cases, incidental observations rather than results of specific investigations. Leitch (1916) obtained by the bleeding of Planorbis a volume of blood which was 33% of the tissue weight. In 1931, Borden determined the blood volume of Planorbis corneus using the Weicker method and obtained a value of 58% of the total tissue weight. This higher value is to be expected, since it is impossible to remove all the blood from an animal by simple bleeding. In 1950, Martin & Huston, using the inulin dilution method, reported the blood volume of Aplysia californicus to be 83·3% of the total weight. This is not surprising since Aplysia has a very extensive haemocoele, and more than half the body weight in blood can be drained in a few minutes from a single incision into the animal.
In Vitro Culture of Embryos in the Silkworm, Bombyx Mori L
Authors: Takami Takeo
Published: April 2021

It is generally believed that the diapausing egg of the silkworm contains a substance which is transmitted from the mother and has an inhibitory action upon the development of the embryo. Watanabe (1924) was the first author to explain the phenomenon of diapause in the silkworm egg by postulating this substance which he called ‘inhibitory substance’, and almost all subsequent authors in Japan have accepted this assumption. It is not unreasonable to suppose that the ‘inhibitory substance’, which reveals its action in the egg after deposition, has some connexion with the diapause factor (hormone) secreted by the suboesophageal ganglion of the mother (Hasegawa, 1951, 1952; Fukuda, 1951), but nothing is known about the real nature and action of the diapause factor (Fukuda, 1955).
The Absorption of Glucose from the Alimentary Canal of the Locust Schistocerca Gregaria (Forsk.)
Authors: Treherne J. E.
Published: April 2021

The absorption of glucose from the alimentary canal of Schistocerca gregaria has been studied by filling the gut with a saline solution containing 14C-labelled glucose together with a dye, Amaranth, which was used as a marker. The net percentage absorption was calculated from the glucose/dye ratio in the various parts of the alimentary canal. The bulk of the glucose was absorbed from the mid-gut caeca, smaller amounts being absorbed by the ventriculus. Glucose absorption was studied at concentrations of 0·002, 0·02 and 0·20 M/1. in solutions in which the total osmolarity was maintained by altering the NaCl concentration. The percentage absorption was similar at concentrations of 0·002 and 0·02M/1., but was significantly less at 0·20M/1. The fate of the 14C-labelled glucose was followed using paper chromatography. The glucose was shown to be rapidly converted to trehalose in the haemolymph. At a concentration of 0·20M/1. this mechanism became saturated and excess glucose accumulated in the haemolymph. The absorption of glucose in vitro, from a gut suspended in a relatively large volume of poisoned saline, was found to be similar to that in the intact insect. From these observations it is suggested that glucose is absorbed by diffusion across the gut wall and that the process is facilitated by the rapid conversion of glucose to trehalose in the haemolymph, which tends to maintain a steep concentration gradient across the gut wall.
Seasonal Variation in the Respiratory Acclimatization of the Leech Erpobdella Testacea (Sav.)
Authors: Mann K. H.
Published: April 2021

In a preliminary study of the oxygen consumption of leeches (Mann, 1956), it was shown that Erpobdella testacea has an oxygen consumption which is independent of the oxygen concentration in the water, over the range 2–6 ml./l., provided that it has been acclimatized overnight to the oxygen concentration of the experiment. The determinations in these experiments were made by enclosing the leeches in glass-stoppered bottles for periods of about 1 hr. Such experiments are unsatisfactory for a study of acclimatization because: (i) the oxygen concentration is constantly changing, (ii) the duration of the experiments is limited, and (iii) the closing of the bottles and the shaking which is necessary to ensure proper mixing of the water make it difficult to keep the animals in a quiescent state. An apparatus was therefore devised to enable the animals to be placed in a slow stream of water of any desired constant oxygen content, so that their oxygen consumption could be measured over a period of days. In this way it was possible to obtain a true resting state, and to investigate acclimatization in differing oxygen concentrations at different times of year.
The Influence of Preoperational Training On the Performance of Octopuses Following Vertical Lobe Removal
Authors: Wells M. J. , Wells J.
Published: April 2021

Blind octopuses were trained to discriminate between two objects by touch by taking one and rejecting the other. When they had learned to do this their vertical lobes were removed and postoperational survival of the effects of preoperational training was tested, either by continuation of training or by means of retention tests. When training was continued after vertical lobe removal animals pretrained at a rate of 8 trials per day for 48 or 96 trials reverted to taking both of the objects to be discriminated (as at the start of training), but subsequently relearned to dis-criminate between them with an accuracy approaching that of controls. They took fewer trials to learn after operation than animals that had not been pretrained. Animals pretrained at a rate of 40 trials per day for 120 trials showed little or no disturbance of learned responses as a result of the same operation. In retention tests carried out immediately after operation, animals pretrained for a similar number of trials at rates of 8 and 40 trials per day made more errors than controls, but showed, nevertheless, that the effects of pretraining by either method were not entirely lost as a result of the operation. These results are discussed in relation to the general problem of the interpretation of discrimination experiments which force animals to react ‘positively’ or ‘negatively’ in an all-or-nothing manner and thereby conceal differences in the degree to which memories are established. It is concluded that the effect of vertical lobe removal can be attributed to a reduction in the amount of tissue available for memory retention.
The Oxygen Dissociation and Alkaline Denaturation of Haemoglobins from Two Species of Earthworm
Authors: Haughton T. M. , Kerkut G. A. , Munday K. A.
Published: April 2021

A method is described for determination of the oxygen dissociation curves of the blood of two species of earthworm, Lumbricus terrestris and Allolobophora terrestris. The following values have been obtained for the partial pressures of oxygen (mm. Hg) required to saturate the blood: Times for alkaline denaturation at pH 12·7 have been found as follows: Lumbricus terrestris 23 min., L. rubelhis 2·5 min., L. festivus 11·5 min., Allolobophora terrestris 6 min., Eisenia foetida 5 min. These results indicate definite differences in the properties of the haemoglobin of the species examined.
Ionic Fluxes in Artemia Salina (L.)
Authors: Croghan P. C.
Published: April 2021

The ionic fluxes between the medium and haemolymph have been studied in adult Artemia salina, under steady-state conditions using 24Na and 82Br. Extremely high fluxes have been found, the flux increasing markedly in the more concentrated media. The results are interpreted as indicating that both the sodium and chloride in the haemolymph are undergoing rapid exchange diffusion with the sodium and chloride in the medium.
The Mechanism of Object Location in Gymnarchus Niloticus and Similar Fish
Authors: Lissmann H. W. , Machin K. E.
Published: April 2021

Experiments with moving electrostatic and magnetic fields show that Gymnarchus niloticus is sensitive to a potential gradient of about 0 · 03 µ V./cm. Alternative explanations of some previous experiments are given in terms of this high d.c. sensitivity. An explanation in similar terms is given of experiments in which Gymnotus carapo is trained to detect a stationary magnet. The mechanisms available for the location of objects by electric fish are reviewed. It is concluded from the results of a critical experiment (described in a succeeding section) that Gymnarchus niloticus can detect objects by the disturbance of its own electric field in the water. The approximate theory of this method of object location is derived. The effect on the receptors of the perturbing field due to an object depends on the electrical properties of the receptors: in the extreme cases the stimulation of the receptors is proportional either to the potential or to its second derivative. Graphs are given showing the effect of an object on the potential and on its second derivative around the surface of the fish. Experiments are described using Gymnarchus niloticus which (a) confirm that the mechanism of object location employs electric field distortion ; (i) indicate the limits of the sensitivity of the fish. The second derivative mode appears to be the most probable one operating in Gymnarchus. The experimentally determined limits of detection are discussed in relation to the random noise in the receptor circuit : it is concluded that both spatial and temporal integration are likely to be employed. The thresholds for object location and for response to direct currents are compared : it is concluded that the same receptors are probably operating in both cases.
Ionic Regulation in the Brown Trout (Salmo Trutta L.)
Authors: Gordon Malcolm S.
Published: April 2021

The osmotic and ionic regulatory abilities of adults of the euryhaline brown trout (Salmo trutta) have been studied in experiments roughly duplicating the stresses of migration from fresh water to the sea. Brown trout will survive indefinitely in full sea water if acclimatized to it at rates inversely related to the temperature. Blood serum samples have been analysed for Na, K, Cl, total P and Δ; muscle samples for Na, K, Cl and total solids. Changes in the concentrations of these constituents following transfers from fresh water to 50% and 100% sea water have been studied. Transfers were made throughout the year and at temperatures of 10° C. and 20°C. Following transfers to 50% sea water at 20° C. blood concentrations rose significantly above fresh-water levels, but returned very nearly to these levels after about a week. Transfer from 50% sea water to 100% sea water at 20°C. caused the same sequence of changes. Transfer to 100% sea water at 20° C. was fatal, and associated with very high serum concentrations. Many fish survived transfer to 100% sea water at 10° C., however, and showed evidence of internal concentrations returning to fresh-water levels after 10 days. The brown trout is strongly homoiosmotic on a long-term basis. Both survival and regulatory ability were lower during the summer. There were also seasonal variations in the blood and muscle concentrations of fish in a given state of acclimatization. Muscle concentration changes closely paralleled blood changes. Extracellular volume remained constant, so muscle concentration changes were attributable to changes in intracellular water. The muscles did not act as storage sites for sodium and potassium.
Studies On the Shoaling Behaviour of Fish
Authors: Steven D. M.
Published: April 2021

Hepsitia stipes and Bathystoma rimator swim in shoals during the day but disperse at night. The fish become increasingly active as illumination decreases and shoals begin to disperse when it falls below about 0·1 f.c. The change from day to night patterns of behaviour is progressive; there is no sudden switch from one to the other at any single level of illumination. Exploratory feeding behaviour similar to normal nocturnal activity can be induced during the daytime by olfactory stimuli. When so stimulated the average swimming speed is about twice as fast as in unactivated fish. Aqueous extracts of mammalian tissues, of marine animals and water in which live plankton has been kept evoke exploratory feeding behaviour. Fish so stimulated attack live plankton which they can see but not reach and will pick up and sometimes swallow pieces of filter-paper which they had previously ignored. The substance in the adductor muscle of Area zebra that excites exploratory feeding behaviour is dialysable and unaffected by boiling. It is effective in concentrations of the order of 1 × 10− 9. Fish can detect trace amounts of many organic substances, to a few of which they respond in a way similar to exploratory feeding, though of less intensity and shorter duration than is the case with extracts of natural food substances. Blinded Bathystoma respond to extracts of Area muscle with a modified type of exploratory feeding behaviour and can locate the position of pieces of food. These experiments are discussed in relation to the behaviour of fish shoals in the sea.
The Composition of the Blood of the Shore Crab, Carcinus Moenas Pennant, in Relation to Sex and Body Size
Authors: Gilbert A. B.
Published: April 2021

The influence of sex and body weight on the concentration of sulphate and chloride ions in the blood of the common shore crab was investigated. Blood chloride increased in both sexes until a maximum was reached at a weight of about 35 g.; thereafter it fell with increasing body weight. Over the whole size range blood chloride was higher in females than in males. This difference was highly significant for animals over 35 g. body weight; below 35 g. however, there was no significant difference between the sexes. Over a restricted size range blood sulphate of males was significantly higher than that of females. Results of the present work have been discussed in relation to those reported earlier for conductivity and total O.P.
The Cuticle ofAcarus SiroL. (=Tyroglyphus Farinae)
Authors: Hughes T. E.
Published: April 2021

The thin cuticle of Acarus siro contains a relatively large quantity of sulphur. The sulphur does not form disulphide linkages between cysteine molecules as it does in keratin. The presence of lysine amongst the products of hydrolysis shows that this cuticle is not tanned by linkage of quinone and amino groups. The experimental data support the view that the cuticle is tanned by reaction of quinones and sulphydryl groups. It is suggested that the quinone involved is a paraquinone, probably derived from phenylalanine.
The Responses of Snails to Polarized Light*†
Authors: Baylor Edward R.
Published: April 2021

Experiments were performed to test whether the polarized light responses of the marine snail, Nassa obsoleta, are mediated by a polarizing analyser within the eye or by the pattern of intensities reflected from the substratum. Snails able to see only the substratum orient at right angles to the plane of vibration of vertically incident polarized light. Snails unable to see the substratum but able to see the overhead source of polarized light fail to orient to the polarized light Implications regarding the rare occurrence of intra-ocular polarizing analysers and the improbability of extensive animal use of polarized light as a navigational aid are discussed.
The Shadow Reaction of Diadema Antillarum Philippi
Authors: Millott N. , Yoshida M.
Published: April 2021

Isolated pieces of test of Diadema bearing a single spine show responses to a constant shadow cast on the radial nerve which are consistent in reaction time, duration, amplitude and frequency of the contractions. Variations in the intensity and duration of the lighting which precedes the shadow exert similar effects on the whole reaction, affecting all the above features. Variations in the duration and intensity (% decrease in intensity of illumination) of the shadow differ in their effects. The intensity affects all the features of the whole reaction, but the duration affects only the later part. The differing effects of light and shade suggest that the shadow response may be a rebound from inhibition due to light which, when re-admitted, diminishes any shadow reaction that may be in progress.
The Cuticular Pattern in an Insect—The Intersegmental Membranes
Authors: Locke M.
Published: April 2021

Grafts including intersegmental membrane have confirmed the existence of a segmentally repeating gradient of incompatibility in the integument of Rhodnius. When host and graft influence one another the pattern can be predicted from the interaction of the gradients. When a graft is uninfluenced by the host the anterior part of the graft is dominant in restoring pattern continuity. The intersegmental membranes are neutral with respect to the gradient behaviour. The gradient is not restricted to the area forming the ripple pattern but includes other patterns in the abdomen.
Responses of the Heliozoon Actinophrys Sol to Prey, to Mechanical Stimulation, and to Solutions of Proteins and Certain Other Substances
Authors: Kitching J. A.
Published: April 2021

Various flagellates and small ciliates stick to the axopods of Actinophrys. Contact with the base of an axopod or with the body surface leads to the outgrowth of a food funnel, by which the prey is ultimately surrounded. If a fine probe or micropipette touches the body surface or the base of an axopod, a small cup may grow out over it, investing it closely, but the instrument is soon released. A squirt of tap water from a micropipette may also provoke the outgrowth of a small lobe or cup, or local pinocytosis. Contact with, or a squirt from, a micropipette containing a solution of egg albumin provokes a more extensive reaction. The micropipette usually becomes invested extensively. The micropipette is drawn into the body and held there for up to an hour. Immersion in egg albumin solution leads to a temporary spreading and lobulation of the axopod bases, and later a ‘skin’ may separate from the body surface. Skin formation is more pronounced in serum albumin solution, and may also be induced by y-globulins and gelatin. On treatment in vivo with toluidine blue or thionine a violet layer in the body surface separates as a pinkish violet or violet skin, leaving the body surface unstained. There is evidence that the skin-forming substance is associated directly or indirectly with the maintenance of cell shape.
Neuromuscular Activity in the Swimming Sea Anemone, Stomphia Coccinea (Muller)*
Authors: Hoyle G.
Published: April 2021

The spontaneous activity and also the response mechanisms to externally applied electric shocks have been studied in the swimming sea anemone Stomphia coccinea obtained from Puget Sound, Washington. Slow rhythmical activity with a repetition interval of the order of 30 min. is evident in kymograph records of whole-animal movements and also in rings of body wall isolated from the oral or basal regions. By suitably placing the stimulating electrodes different parts of the musculature can be brought into contraction. Those studied were principally the parieto-basilar muscles and also the longitudinal retractors, the circular muscles of the column and the isolated oral sphincter. The magnitude of the response of the parieto-basilar muscles to constantstrength stimuli was very variable. Responses occur to single shocks and these increase in magnitude with increasing strength of stimulus. The parietal muscles give delayed, slow contractions in response to trains of about ten stimuli at one per sec. The isolated sphincter muscle shows two kinds of contraction, a quick one which occurs to single shocks and a slow one which occurs following a brief train of fairly widely separated shocks. The ordinary circular muscles respond with a slow contraction to a few widely spaced shocks. They do not give quick contractions. Although in many cases animals responded to eight quick shocks by giving swimming reactions this number was not found to be a precise requirement, and it varied for the same animal at different times in an unpredictable manner as well as varying from one animal to another. On one occasion a swimming response occurred after a single shock and on another after twenty-eight shocks. It was found that the state of ‘facilitation’ (occurring in the response to electric shocks) of the muscles used in swimming varied a great deal but did not show any marked long-term change following a single shock or the elicitation of a swimming response.
The Reflex Co-Ordination of the Heart Beat with Respiration in the Dogfish
Authors: Satchell G. H.
Published: April 2021

The hearts of Squalus lebruni and Mustelus antarcticus beat at intervals that approximate to some simple multiple (1-4) of respiratory cycle length. The beat tends to be initiated during a particular phase of the respiratory cycle, most commonly just before or just after the opening of the mouth. Possible mechanisms of this co-ordination are considered and evidence is presented to show that it is reflexly mediated. Fibres from receptors fired by pharyngeal dilatation are believed to constitute the afferent limb, and the cardiac vagi the efferent limb of the reflex arc. Simultaneous records of blood pressure have been made from the 1st afferent branchial artery and the coeliac artery. By subtraction, the differential pressure across the gill vessels has been calculated and found to have a peak early in the cardiac cycle. Simultaneous photo-electric records of gill opacity and branchial blood pressure show the gill vessels to be compliant. It is concluded that there is a brief period of rapid blood flow early in each cardiac cycle. Calculations from simultaneous records of the electrocardiogram and branchial blood pressure showed that heart beats originating near the time of mouth opening caused a rapid flow of blood through the gills at the time that water was expelled across them. It is suggested that this synchronization of the periods of rapid flow of blood and water serves to maintain the diffusion gradient of oxygen across the gill epithelium.
The Arginase Activity of the Tissues of the Earthworms Lumbricus Terrestris L., and Eisenia Foetida (Savigny)
Authors: Needham A. E.
Published: April 2021

The difference in arginase activity between the tissues of Eisenia and those of Lumbricus shows a relationship to the difference in urea output by living worms of the two species under the same dietary regime. In Eisenia the difference in activity between the tissues of fasting and feeding worms is much smaller than in Lumbricus. The specific outputs of urea by living, fasting and feeding worms likewise differ less than in Lumbricus. These facts strengthen previous evidence in favour of a Krebs-Henseleit type of mechanism for urea production in earthworms. In Eisenia the difference in arginase activity between gut and body wall is similar to, but smaller than, that in Lumbricus, and the body wall makes a major contribution to the total activity. The combined concentrations of ammonia-, amino-, and urea-nitrogen initially present in homogenates of the tissues of these worms are proportional to the combined amounts of the three components excreted per unit weight by living worms of the same species and regime. The two species differ in a number of other properties investigated.
Experiments on the Influence of Light on the Behaviour of Polyzoan Larvae
Authors: Ryland J. S.
Published: April 2021

An apparatus is described for investigating the photic responses of marine larvae. A parallel beam of light is projected along horizontal Perspex troughs containing the larvae, while the use of a water bath prevents their being subjected to a rise in temperature. Using a light beam of 5000 lux at normal summer sea temperatures, plotting the positions of the larvae in the troughs at regular intervals has revealed four types of behaviour : I. Larvae at first all photopositive, later all becoming photonegative ; for example, Celleporella hyalina. II. Larvae at first all photopositive, only a small proportion of them later becoming photonegative ; for example, Bugula neritina. III. Larvae photopositive throughout the length of their natant phase; for example, Flustrellidra hispida. IV. Larvae showing no response at all to directional illumination ; for example, Alcyonidium polyoum. It has been shown that the reversal of the sign of reaction to light in Celleporella hyalina larvae is dependent on the passage of time; it does not require their exposure to a certain amount of light for its inception. When disks cut from Fucus serratus fronds were placed in the troughs as a substrate for settlement, the majority of Celleporella hyalina larvae developed a photonegative reaction before they metamorphosed. Horizontally and vertically placed panels in the Menai Straits received settlement of polyzoans on all surfaces free from sediment and dense algal cover. These adverse factors would have masked any selection based on the behavioural responses of the larvae. Laboratory experiments with opaque panels suspended vertically, obliquely and horizontally have shown that Celleporella hyalina larvae settle on the side away from the light. Thus they normally settle on the undersurfaces of horizontal and oblique panels, but this pattern is reversed if the panels are lit from below. Settlement on panels in the sea would therefore seem to depend on the reactions of larvae to light as well as on the unfavourability of upward-facing surfaces. The nature of the larval responses is discussed.
The Mode of Operation of the Electric Receptors in Gymnarchus Niloticus
Authors: Machin K. E. , Lissmann H. W.
Published: April 2021

Two possible modes of action of the electric receptors of Gymnarchus niloticus are described. In one, received pulses are ‘smoothed’ and a sensory discharge occurs dependent only on the smoothed level (‘pulse-frequency-modulation’). According to the other mechanism, sensory nerve impulses are produced at the same frequency as the received pulses, but after a delay dependent on their amplitude (‘pulse-phase-modulation’). An experiment has been devised to distinguish between the two mechanisms, and, if the pulse-frequency-modulation mechanism is the operative one, to measure the smoothing time-constant. The results favour the pulse-frequency-modulation mechanism, and indicate a smoothing time-constant of 25 msec. It appears also that adaptation takes place in the electric receptors. The origin of the smoothing action is discussed. The sensitivity of electric receptors is compared with that of other sense organs.
Studies on Ionic Regulation in Carcinus Maenas (L.)
Authors: Shaw J.
Published: April 2021

The mechanism of sodium balance in Carcinus maenas has been investigated. Measurements of sodium outflux showed no evidence of a decrease in surface permeability to sodium in dilute sea water. The rate of urine production in normal sea water was 3·6% body weight per day and the sodium loss through the urine was insignificant compared with the total sodium loss. In 40% sea water the urine rate was increased to 30% body weight per day and the loss in the urine accounted for 20 % of the total loss. Measurements of sodium influx and calculation of the active component showed that the active uptake mechanism was fully saturated at all external concentrations in which the animals could survive. Regulation of the blood sodium concentration is effected largely by the activation of the sodium uptake mechanism. This prevents the blood concentration falling below a critical level as long as the external concentration itself is not too low.
Fuel Utilization and Duration of Tethered Flight in Aphis Fabae Scop
Authors: Cockbain A. J.
Published: April 2021

Fat contents (ether extracts) of unflown 24 hr. old alatae of Aphis fabae Scop., from different host plants, range from 3−12% of the live weight and 9−33 % of the dry weight. Glycogen contents of alatae reared in culture range from 0·5−1 % of the live weight and 1·7−3·4% of the dry weight. Both fat and glycogen are consumed during tethered flight. Glycogen is used during early flight and fat is the principal fuel after the first hour, when it is consumed at a mean rate of 0·005 mg./aphid/hr. and provides about 90 % of the energy for a 6 hr. flight. The amounts of glycogen in laboratory-reared aphids alone could not maintain flight for more than 34 hr. Metabolic rates during tethered flight range from 52 to 66 cal./g. live wt./hr. or 11−14ml. O2/g./hr. The flight muscles constitute about 13% of the live body weight of 24 hr. old aphids, and, attributing most of the metabolism during flight to these muscles, their metabolic rates range from 400 to 500 cal./g./hr. Flight capacity of 24 hr. old aphids at 25−26°C. is directly related to initial fat content and varies between 3 and 8 hr. in aphids from culture (mean of 4 % fat by live weight) and between 7 and 12 hr. in aphids from the field (10% fat). Flight fatigue occurs before all the fat reserves are used; possibly fat stored in parts of the body remote from the flight muscles cannot be mobilized rapidly enough to support continuous flight. Fat and glycogen reserves occur mainly in the fat-body cells of the thorax and abdomen; fat also occurs between the fibrils of the indirect flight muscles and glycogen along the surface of the fibres. Flight-exhausted insects have little or no fat in the thorax, but small deposits remain in the abdomen; little glycogen can be detected in culture aphids flown to exhaustion.
The Response of A Hydroid to Weak Water-Borne Disturbances
Authors: Josephson Robert K.
Published: April 2021

Syncoryne mirabilis polyps rapidly bend toward the source of a mechanical disturbance in their vicinity. A small moving copepod a few millimeters from the polyp creates sufficient stimulus to evoke this response. The hydroid will respond to a mechanical pulse from an electrically driven prodder as well as to single movements of the prodder either toward or away from the polyp. With the prodder 0.5 mm. from the polyp mid-line, threshold displacement of the prodder is only 2.5-3µ. Repeated pulses of increasing amplitude, initially below threshold intensity, will not evoke bending if the frequency is over 5/sec. This means that stimuli which cause no overt response can still inhibit polyp bending to normally supra-threshold subsequent stimuli. A polyp will not respond to slow currents of water, but will bend towards the source of sudden jets of water directed at it. The capitate tentacles are not necessary for the movement perception, but after their removal the threshold is raised and the accuracy of bending reduced. The response does not require that the polyp be attached to a fixed stalk; it also occurs in isolated polyps floating in a density gradient. The hypothesis is presented that polyp bending is due to unequal stimulation of opposite sides of the polyp because of decreasing stimulus intensity with increasing distance from the source of disturbance.
The Mechanism of Orientation of Freely Moving Littorina Littoralis (L.) to Polarized Light
Authors: Charles G. H.
Published: April 2021

The mechanism of orientation of Littorina littoralis (L.) to plane polarized light was investigated by means of a servo-mechanism, whereby the intensity of the polarized light was varied with the orientation of the winkle to the plane of vibration. It was shown that these controlled variations in light intensity augmented or decreased the efficiency of orientation. When the light was altered with change in orientation in a direction which would be expected to counteract the Fresnel reflexion/refraction mechanism a fall in responses to polarized light was observed. Random changes in the light intensity of the polarized beam also interfered with the orientation. The influence of reflected patterns of light and shade from the surroundings on the orientation of L. littoralis to polarized light was investigated with the use of the eye shields and with surfaces of different reflective properties. It was conclusively shown that the winkles could orientate both by direct perception of the plane of vibration by the eyes and to comparatively small differences in light intensity in the pattern of light reflected from the substratum.
Orientational Movements of the Foot of Littorina Species in Relation to the Plane of Vibration of Polarized Light
Authors: Charles G. H.
Published: April 2021

Littorina littoralis (L.), L. saxatilis (L.), L. neritoides (L.) and L. littorea (L.) responded to the plane of vibration (e vector) of polarized light directly incident upon their eyes in the virtual absence of any substrate reflexions. Photonegative winkles orientated parallel with the plane of vibration and photopositive individuals at right angles to this plane. Decrease of the angle of incidence towards zero of polarized light rays incident upon the lens aperture of Littorina littoralis completely destroyed the ability to orientate to the plane of vibration. This can be explained on the basis of a Fresnel reflexion/refraction mechanism of orientation. Unilaterally blinded Littorina littoralis gave just as good an orientation to vertical rays of polarized light as winkles with intact vision. It is concluded that the eyes of Littorina species are capable of detecting the plane of vibration of polarized light directly incident from above by means of a Fresnel reflexion/refraction mechanism, and that orientation does not depend on balanced stimulation of the two eyes.
Effect of Acclimatization to High Temperature on the Blood Chloride, Free Amino Acids and Osmotic Pressure in the Freshwater Field Crab Paratelphusa Sp. and the Freshwater Mussel Lamellidens Marginalis
Authors: Rao Kandula Pampapathi , Ramachandra R.
Published: April 2021

Acclimatization of the freshwater field crab, Paratelphusa, to high temperature results in a decrease in the chloride, free amino acids and osmotic pressure of the blood.

Following similar acclimatization the freshwater mussel, Lamellidens marginalis unlike the crab, shows a considerable increase in the blood chloride as well as the free amino acids, while the total osmotic pressure increases relatively little.

These results are discussed and it is suggested that the ionic and osmotic gradient between the milieu intérieur and the protoplasm of the cells might be important in the metabolic compensation to temperature.
Evidence for Humoral Regulation of Digestive Secretion in the Beetle, Tenebrio Molitor
Authors: Dadd R. H.
Published: April 2021

Midgut protease values of starved adult Tenebrio injected with the blood of recently fed adults were, on average, higher than those of similar recipients of the blood of starved donors, or of untreated starved adults of the same age. A similar increase was found in the recipients of blood of newly-emerged adults. Protease activity failed to develop in the midguts of adults which had been decapitated one day before emergence. If decapitation occurred after emergence, enzyme activity developed, but at a slower rate and to a lower maximal level than in the normal adult. Inhibition of the development of enzyme activity was greater the sooner decapitation followed emergence. A few experiments suggested that injection of the blood of normal newly emerged adults could to some extent rehabilitate the development of enzyme inhibited by pupal decapitation. These observations are discussed in relation to the hypothesis that digestive secretion may be under humoral regulation.
The Waterproofing Mechanism of Arthropods
Authors: Beament J. W. L.
Published: April 2021

The permeability to water of the cuticles of a number of aquatic insects has been measured under conditions of evaporation. The range of rates of evaporation amongst these animals is very great; some adult aquatic beetles are quite as waterproof as more permeable terrestrial insects (caterpillars for example), whereas their larvae would seem to be without specific mechanism for restricting the passage of water. Two methods are described, whereby local differences in permeability may be detected, and from one of these methods it is possible to calculate the permeability/ temperature characteristics of different areas of cuticle of an intact insect. The more impermeable insects have uniform permeability over their entire surfaces; these include adult beetles, and both mature and immature stages of Hemiptera. Larvae of mayflies and of some beetles, which are very permeable to water, likewise show no local differences in permeability. The gills of all the species examined are very permeable to water; those of zygopteran dragonflies are more permeable than the rest of the cuticle at lower temperatures, those of Sialis are much more permeable at all temperatures. The effect of temperature upon permeability has been measured. The more waterproof insects reveal transition phenomena characteristic of organized monolayers of lipid, such as are found in terrestrial insects, but by comparison with them the temperatures at which transition occurs are very low. In particular, the temperature at which adults of Dytiscus and Gyrinus become suddenly more permeable (ca. 25° C.) could obtain in natural circumstances, and the evidence suggests that these animals die through osmotic invasion of water when placed at higher temperatures. Other beetles and aquatic Hemiptera, with higher transition temperatures, survive temperatures above 25° C. These ecological implications are discussed. A transition phenomenon occurs in organized lipid over the main cuticle of Sialis, whereas the more permeable gill shows no evidence of this. There is no evidence for organized lipid on the main cuticle of zygopteran larvae, but the temperature/permeability relations of the general cuticle and of the gill are very different. The absolute permeability, and the shape of the permeability/temperature function, of the cuticle of those insects which have very hydrofuge areas of surface suggest that their waterproofing system consists of only one monolayer of organized lipid, which may be either grease or wax.
On the Regulation of the Respiration in Reptiles
Authors: Nielsen Bodil
Published: April 2021

Ventilation of the lungs accomplished by movements of the ribs is, in the phylogenetic development of the animals, first found in the reptilian class. It may therefore be of interest to investigate the regulation of respiration in this group. The reactions to carbon dioxide and to low oxygen tensions is specially interesting considering the importance of these substances for the respiratory regulation in higher animals and man.
The Responses of Certain Mysids to Changes in Hydrostatic Pressure
Authors: Rice A. L.
Published: April 2021

Four mysid species have been found to exhibit responses to changes in hydrostatic pressure. The orientation of these responses has been observed in normal animals, and also in ones from which the statocysts had been removed. The results have helped to confirm earlier work on mysids, and indicate that at least three mechanisms are involved in orientation in this group. These mechanisms are (a) orientation to gravity via the statocysts, (b) the dorsal light reflex and (c) the general position reflex. One of the species used has been shown to respond to slow pressure changes of the same order as those due to tidal rise and fall, and it is suggested that the pressure responses may be important in the tidal migrations of shallow-water mysids.
The Role of the Antennal Gland in the Osmotic and Ionic Regulation of Carcinus Maenas*
Authors: Riegel J. A. , Lockwood A. P. M.
Published: April 2021

Several previous studies on various littoral and semi-terrestrial crabs [Carcinus maenas—Nagel (1934), Webb (1940); Pachygrapsus crassipes—Prosser, Green & Chow (1955), Gross (1959), Gross & Marshall (1960); Uca pugnax and U.pugiator— Green, Harsch, Barr & Prosser (1959)] have pointed out the effective role of the antennal gland in regulating the ionic concentration of the urine in sea water of various concentrations. Recently, Flemister (1958) and Green et al. (1959) have suggested that in certain of the more terrestrial crabs (Uca spp. and Gecarcinus lateralis) water may be reabsorbed from the urine. Riegel (unpublished) has obtained direct evidence of the withdrawal of water from the urine of Hemigrapsus nudus. As will be shown here, specimens of Carcinus maenas are also capable of withdrawing water from their urine in 100% sea water or in water-saturated air. In addition, specimens of C. maenas can also alter the urine/blood (hereafter designated U/B) ratios of sodium, magnesium, chloride, osmotic pressure and possibly calcium.