bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Paradox of Mytilus Muscle. A New Interpretation
Authors: Hoyle G. , Lowy J. 
Published: April 2021

ABSTRACT
The mechanism of contraction and relaxation in the anterior byssus retractor muscle (A.B.R.M.) of the lamellibranch mollusc Mytilus edulis has been studied with refined stimulating and recording techniques. Two distinct types of response are present: phasic and tonic. The former can be evoked by all kinds of electrical stimulation, but the latter is most readily elicited by continuous direct current. Serotonin (5-hydroxytryptamine) rapidly abolishes the tonic response, whilst leaving the phasic response practically unaffected for many hours. On electrical stimulation, a serotonin-treated muscle may show spontaneous electrical and mechanical activity, usually of a rhythmical nature. As the muscle is unable to destroy this drug the effects produced by it are likely to be of pharmacological interest only. Electrical activity in the form of irregular volleys of muscle action potentials can be recorded from the intact A.B.R.M. and even after the nerves to the muscle have been cut. In such (externally) denervated preparations the spontaneous electrical activity is almost unaffected by a.c. stimulation but greatly increased by d.c. stimulation which evokes prolonged tonic contraction. Stimulation of inhibitory nerves within the muscle quickly terminates a state of tonic contraction and at the same time reduces the electrical activity considerably. An explanation is offered for the occurrence of electrical activity during relaxation of lamellibranch smooth muscles. The normal functioning of the A.B.R.M.is interpreted, and strong support is given to the tetanus hypothesis of tonic contraction.
Proteolytic Activity of the Midgut in Relation to Feeding in the Beetles Tenebrio Molitor L. and Dytiscus Marginalis L.
Authors: Dadd R. H. 
Published: April 2021

ABSTRACT
Where quantitative methods have been applied to the study of insect digestion, enzyme activity has generally been shown to increase after feeding, often with change in location of maximum enzyme concentration (Schlöttke, 1937 Or-c ; Duspiva, 1939; Day & Powning, 1949; Fisk & Shambaugh, 1952). The most marked responses described by these authors occur in carnivorous and blood-sucking insects, and to some extent this supports the view put forward on histological grounds by Haseman (1910), that discontinuous secretion is associated with the carnivorous habit of taking discrete meals.
Effects of Hypothermia and Hyperthermia on Fertilization in Rat Eggs
Authors: Austin C. R. 
Published: April 2021

ABSTRACT
The chilling of rats to body temperatures down to 4-7° C. before and during the time of ovulation had little effect upon the subsequent penetration of the eggs by spermatozoa. With a hypothermia of 0-1° C, however, there was almost complete and apparently permanent inhibition of spermatozoon entry. There seemed to be no reason to ascribe this effect to direct influence of cold on eggs or spermatozoa. Probably the failure of penetration arose largely from delay of ovulation, coupled perhaps with some derangement of the tubal environment.
Hypothermia after ovulation but before and during the time of spermatozoon entry into the eggs temporarily but completely inhibited penetration when the body temperature was kept below 33° C. The likely explanation appears to be that ‘capacitation’ is prevented or greatly slowed by such temperatures.
Hyperthermia, induced before and during the time of ovulation, somewhat reduced the mean number of eggs ovulated (from 10.5 to 7.5) and the proportion penetrated by spermatozoa (from 97 to 66%). The proportion of eggs penetrated by two or more spermatozoa was increased (from 19 to 28%), but the frequency of polyspermic fertilization did not change significantly.
Hyperthermia after ovulation but before and during the time of spermatozoon entry also led to a greater proportion of eggs containing two or more spermatozoa (31%), but in addition it increased the incidence of polyspermy (from 2.5 to21.2%). Larger rats (170-200 g.) subjected to hyperthermia showed a higher frequency of polyspermy (34%) than smaller rats (100-130 g.; 13% polyspermy).
Evidently the processes involved in the ‘zona reaction’ are reduced in efficiency by hyperthermia whether applied before or after ovulation. On the other hand, the block to polyspermy depends on processes that are much more sensitive to heat after ovulation. It is considered that the slowing down of the block to polyspermy is associated with ageing of the egg, that the ageing is accelerated by hyperthermia and that this effect is promoted in older rats.
Pressure Receptors in the Fins of the Dogfish Scylliorhinus Canicula
Authors: Lowenstein Otto 
Published: April 2021

ABSTRACT
The presence of so-called terminal corpuscles in the connective tissues of the fins of Scylliorhinuis canicula, first described by Wunderer in 1908, is confirmed. It is demonstrated that they are pressure receptors with a slow rate of adaptation. From their topographic distribution and from their mode of response to mechanical stimulation, it is postulated that the terminal corpuscles serve as proprioceptors in the widest sense of the term by signalling the spatio-temporal patterns of active or passive deformation of the fin. Their topographic distribution makes it possible to distinguish their responses from those of sense endings associated with the muscles or tendons of the fin.
The Interaction Between Metals and Chelating Agents in Mammalian Spermatozoa
Authors: White I. G. 
Published: April 2021

ABSTRACT
Several studies have been made on the bacteriostatic and fungicidal properties of oxine (8-hydroxyquinoline) and other chelating agents, and it has been suggested that they might act, in part at least, by depriving cells of essential trace metals (Albert, 1951; Martell & Calvin, 1952).
Some Aspects of Osmotic Regulation in Lampreys
Authors: Hardisty M. W. 
Published: April 2021

ABSTRACT
The mean osmolar concentration (expressed as mM. NaCl/l.) of the serum for Lampetra planeri was found to be no mM. in the ammocoete and 113 mM. in the adult. For adult L. fiuviatilis szerum in November the mean osmolar concentration was 143 mM. and in March 136 mM. In adult planeri the Cl concentration of the body fluids accounted for nearly 90% of the total concentration as compared with only 58% in the serum of the ammocoete. Adult fiuviatilis kept in tap water throughout the winter appeared to show an increase in Cl levels. Evidence has been produced to support the view that the differences observed in water, fat and Cl content of ammocoete and adult planeri and adult fiuviatilis are consequences of the period of starvation preceding sexual maturity. Pronounced seasonal variations have been found in the fat and Cl content of ammocoetes of planeri. The osmotic uptake of water has been determined for adults of both species in fresh water. In planeri the rate of uptake for unit body weight is about four times as great as in fiuviatilis. Observations have also been made on the osmotic loss of water of ammocoete and adult planeri and of adult fiuviatilis in sea water of different concentrations. For unit body weight osmotic loss of water in planeri is about twice that of fiuviatilis. Total losses of Cl have been determined for ammocoete and adult planeri in distilled water and their effects on internal Cl levels have been studied. Observations have also been made on the active uptake of Cl. Acclimatization experiments on ammocoetes and adult planeri and on adult fiuviatilis have failed to produce any evidence of regulation in sea water.
Control of the Melanophores of the Minnow (Phoxinus Phoxinus (L.))
Authors: Gray E. G. 
Published: April 2021

ABSTRACT
The effects of sectioning the nerve fibres supplying a tail area of melanophores in the minnow under various experimental conditions were studied by a method of continuous observation employing visual and photomicrographic recordings. In the white-adapted fish, nerve section causes a band of melanophores to disperse. The initial dispersion later subsides, the band melanophores aggregating first at the band margins (primary fading). Subsequently the band melanophores react to background reversals in a similar way to normal ones. Hypophysectomy does not interfere with the initial dispersion or primary fading of band melanophores. Furthermore, these melanophores still react tobackground reversals, but in this case they react first at the margins of the band. Prolonged white-adaptation, favouring maximal activities of aggregating pituitary hormones, does not prevent the initial dispersion resulting from nerve section. Band melanophores with fibres sectioned 5 days previously react to diffusing aggregating neurohumours liberated by electrical stimulation. Melanophores with fibres newly sectioned remain dispersed, refractory to this aggregating agent. When the chromatic fibres at the level of the spinal cord are sectioned in a white-adapted fish with a faded tail band the normal melanophores disperse and later the band melanophores disperse first at the margins. A possible interpretation is that dispersing neurohumours are liberated by spinal section. Asymmetric responses of melanophores indicate that neurohumours can activate located regions of the individual melanophore. The mechanism of the melanophore dispersion resulting from nerve section is discussed together with the question of single or double innervation and the related activities of aggregating and dispersing neurohumours.
Endocrine Activity During Insect Embryogenesis. Control of Events in Development Following the Embryonic Moult (Locusta Migratoria and Locustana Pardalina, Orthoptera)
Authors: Jones Bryn M. 
Published: April 2021

ABSTRACT
Secretory activity of the ventral head glands in embryos of Locustana pardalina and Locusta migratoria is necessary for inducing the moult and controlling subsequent events in late development. Continued secretory activity of the glands for a period after the moult is required for further progress in development. The development hormone released by the glands activates in turn the pleuropodial glands. The latter, in order to become fully functional, also require the continued secretory activity of the endocrine glands for a period after the moult. The enzyme-substrate system responsible for the formation of melanin does not become active until the development hormone is liberated. However, the system was present in the egg beforehand in an inactive state and it is suggested that it is held in check by an inhibiting influence. The amount of melanin deposited appears to be correlated with the amount of development hormone released.
The Effect of Temperature Upon the Permeability to Water of Arthropod Cuticles
Authors: Mead-Briggs A. R. 
Published: April 2021

ABSTRACT
The effect of temperature alone upon the permeability of arthropod cuticles has been investigated by measuring the rate of transpiration into a constant saturation deficit at a number of temperatures. The permeability of the cuticles of Oniscus asellus and Lithobius sp. is little affected by temperature. The cuticles of Calliphora erythrocephala, Glossina palpalis, Blatta orientalis and Periplaneta americana become progressively more permeable as the temperature is raised from 30 to 50, or 55° C. That of Tenebrio molitor larvae behaves similarly, but the increase in permeability is less marked until the temperature rises above 40° C. The progressive increase in permeability of the cuticle of Periplaneta is entirely eliminated if the soft wax coating is removed. The increase in permeability of the insect cuticle with temperature is approximately exponential and cannot result from a single, abrupt change in a wax layer at a ‘critical temperature’. Possible physical bases for a continuous change are discussed.
Temperature Relations of Teneral Development and Behaviour in Aphis Fabae Scop
Authors: Taylor L. R. 
Published: April 2021

ABSTRACT
The teneral stage in Aphis fabae Scop, is defined as the interval between eclosion of the alate imago and flight when flight is not extrinsically activated or inhibited. In field marking experiments the teneral stage is shown to be usually development-limited, not behaviour-limited, by its relationship to temperature. It is suggested that the logistic curve fits the rising temperature × development-velocity curve because this is a statistical distribution like the Pearson type 1. The logistic curve is fitted to teneral period in naturally varying temperatures by a method of successive approximation. In trapping experiments take-off is inhibited by light below c. 100 f.c. and by temperature below c. 16° C. at 1 ft. in a bean crop. These behaviour responses sometimes lengthen the apparent teneral period. The results are confirmed in the laboratory at constant and at varying temperatures. This also confirms that temperature changes per se even over a range of c. 7-34° C., and other climatic factors, have negligible effect on rate of development during the teneral period. Individual variation is a constant proportion of teneral time at all temperatures. In laboratory experiments the same criteria apply to Aglais urticae L. This period of inactivity warrants further examination in an ecological context.
Spectral Sensitivity of Chromatophores in Diadema Setosum (Leske)*
Authors: Yoshida Masao 
Published: April 2021

ABSTRACT
Classical accounts of the effect of coloured light on retinal pigment migration in frogs and crayfish have been reviewed by Parker (1932). Most of those results agree in indicating violet or blue as the most effective light. Zetter (1956) has shown that the light of wavelengths near to 540 m/x is most effective for the expansion of melanophores in frog’s skin. On the other hand, the direct effect of light upon the iris, which responds like melanophores, shows that 486 mμ is the most effective wavelength (Weale, 1956).
Rotation Experiments with Blind Goldfish
Authors: Jones F. R. Harden 
Published: April 2021

ABSTRACT
Blind goldfish react to rotation at constant angular velocity by swimming against the direction of rotation so as to maintain, on the whole, the same orientation or bearing relative to earth. The lowest angular velocity to which the fish appear to react is below 10°/sec. For the best performers the threshold is about 3°/sec. The stimulus to which the fish responds is not one of contact, initial swirl or water current (when the turntable gets under way), variation in turntable velocity or centrifugal force. The semicircular canals are probably the sensory channels through which a fish is able to detect rotation at constant velocity and the mechanical stimulus to which it responds is probably an angular acceleration. How the fish becomes aware of angular accelerations during rotation at constant velocity is not yet understood.
Amino-Acid Metabolism in Locust Tissues
Authors: Kilby B. A. , Neville Elisabeth 
Published: April 2021

ABSTRACT
Homogenates of fat-body of Schistocerca gregaria Forsk. were shown to catalyse transamination reactions between α-ketoglutarate and. numerous α-amino acids. The aspartate/glutamate and alanine/ghitamate transaminases were the most active. They were present in both the ‘soluble ‘and the mitochondrial fractions of fat-body cells and also in Malpighian tubules and mid-gut wall. The other transaminases in the fat-body were confined to the mitochondrial fraction. Fat-body, Malpighian tubule and mid-gut wall homogenates were able to convert glutamic acid into glutamine, a compound which could also act as an amino-group donor in some transamination reactions. A glutamate-cytochrome c reductase system which involved diphosphopyridine nucleotide was present in fat-body. Fat-body contained an active arginase, but urease could not be detected. A D-amino-acid oxidase was present, together with a less active L-amino-acid oxidase. In general, it appears that amino-acid metabolism in the locust resembles that in higher animals.
Repeated Presentation Experiments and the Function of the Vertical Lobe in Octopus
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
When presented with a small object that it has not previously encountered, an octopus passes the object to its mouth and attempts to eat it. Inedible objects are rejected after a period of minutes, and when the same object is repeatedly presented at short intervals, the animal rapidly learns to examine and reject it without passing it to the mouth. That the animal is learning to recognize a particular object and not merely becoming fatigued or generally less reactive can be demonstrated by changing the object; a new object is almost always taken, even if the animal has not taken the original for many trials. After a break in training of the order of hours, the animal may accept the same object when it is presented again, but relearns not to take it in fewer trials than in the original training. The performance of two animals tested after removal of the optic lobes was in all respects comparable to that of three controls (two unoperated and one with the optic nerves cut). Six animals with the vertical lobe of the brain removed were also tested. The performance of these animals differed from that of five controls in two respects: they took six times as long to examine and reject the objects in the first trial, and they showed relatively poor retention following breaks in training. The first of these differences is particularly important because it shows that removal of the vertical lobe has effects other than increasing the rate of fading of memories between trials. The significance of this in the interpretation of the function of the vertical lobe from discrimination experiments is discussed.
Studies on the Influence of the Embryonic Environment on the Post-Hatching Development of Chickens
Authors: Ryle Margaret 
Published: April 2021

ABSTRACT
Techniques are described for removing and replacing approximately 15% of the total volume of yolk after 5 days’ incubation, or of albumen after 2-3 days’, in hens’ eggs. These allow up to 50 and 40% respectively of the eggs to hatch. Yolk and albumen were exchanged between different breeds of chickens, and chicken eggs received yolk and albumen from other species. Embryonic viability was not reduced by egg constituents of other breeds or species. Small numbers of chickens from eggs which received turkey, goose and duck yolk, and larger numbers from eggs which received turkey albumen, were hatched and reared successfully; they appeared to be quite normal. Legbar eggs received yolk from Polish Bantam eggs. The experimental birds weighed significantly less than their control siblings at 139 days. The mean shank lengths were not significantly different. Attempts to repeat the experiment failed to support this result ; possible reasons for this are discussed. Polish Bantam eggs received yolk from Dorbar eggs. At 100 days they were significantly heavier than their control siblings, but their mean shank lengths were almost identical. In each of the four 1955 albumen exchange experiments the mean weight of the experimental birds at 170 days was greater than that of their control siblings, but not significantly so. On pooling the data a significant difference was found at 100 and 114 days (P=0-05) and 170 days (P&lt;0·02). The mean shank lengths were very similar. The 1956 experiments failed to confirm these results; possible reasons for this are discussed. It appears that, in certain circumstances, exposure of the embryo to ‘foreign’ yolk or albumen may influence post-hatching growth in weight, but this effect is only detectable when the chicks are over 3 months old.
Flight Activity in the Blowfly Calliphora Erythrocephala, in Relation to Light and Radiant Heat, With Special Reference to Adaptation
Authors: Digby Peter S. B. 
Published: April 2021

ABSTRACT
The spontaneous flight activity of a population of the blowfly Calliphora erythrocephala has been studied in relation to light and radiant heat in a small wind tunnel. Flight activity occurs at a low level in the dark under these conditions, and is practically independent of light up to 10 lux. Activity increases sharply with light between 10 and 2600 lux, before heating effects become important. Population activity shows adaptation to light intensity, and a method of analysis is described. The rate of increase of activity following an increase of light is much slower than is the reverse change; the state of low activity at low light intensities tends to persist. Complete adaptation would take at least a number of hours. Heating, which accompanies strong light intensities, causes initially a momentary decrease in activity, usually followed by an increase. Similar reactions occur when the heat is applied in several different ways."
The Speed of Swimming of Fish as Related to Size and to the Frequency and Amplitude of the Tail Beat
Authors: Bainbridge Richard 
Published: April 2021

ABSTRACT
An apparatus is described in which it is possible to study and record the continuous swimming of fish at speeds up to 20 m.p.h. Records made of the swimming at different speeds of dace, trout and goldfish measuring up to 30 cm. in length are reproduced. Speed at any particular frequency of tail beat is shown to be directly related to the length of the specimen, measured from the tip of the snout to the most posterior extremity of the tail. Above a frequency of 5 tail beats per second speed is directly dependent upon frequency up to the maximum values recorded. The results for all sizes and species recorded may be adequately expressed by the formula , where V is the speed in cm. per sec., f is the frequency in beats per sec. and L is the body length in cm. The distance travelled per beat (and hence the speed) is directly dependent upon the amplitude of the tail beat. The amplitude increases with increasing frequency up to a maximum reached at about 5 beats per second. This maximum amplitude is the same for all fish tested and is about one-fifth of the body length. The maximum frequency attainable decreases with increasing size of the specimen. This decrease is slight in the trout and more pronounced in the dace and goldfish. Estimation of the possible maximum frequencies of much bigger fish allows for prediction of the maximum speeds they may be able to attain. Such predicted speeds are in accord with the few measurements that have been made and are of the order of 10 body lengths per second up to a size of 1 m.
The Survival of Artemia Salina (L.) in Various Media
Authors: Croghan P. C. 
Published: April 2021

ABSTRACT
The survival of Artemia salina adults in various media has been studied. Prolonged survival is only possible in media in which certain sodium salts (principally NaCl) predominate. Certain substances are found to be highly toxic. It is confirmed that the high toxicity of potassium ions can be antagonized by sodium ions. The results indicate that the animal is appreciably permeable.