bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Observations on the Effect of De-Afferentation on the Locomotory Activity of Amphibian Limbs
Authors: Gray J. , Lissmann H. W. 
Published: April 2021

ABSTRACT
The extent to which co-ordinated rhythmical patterns of locomotory movement are to be regarded as expressions of intrinsic activity within the central nervous system, and how far they are dependent upon the patterns of impulses received from peripheral sense organs, remains a fundamental problem in general physiology. In previous communications we have discussed this problem with reference to the ambulatory activity of Amphibia (Gray & Lissmann, 1940). We found that when the limbs and body of a toad (Bufo bufo) are desensitized by severance of their sensory nerves, the effect on the locomotory pattern depends to a very marked degree upon the extent to which the process of de-afferentation has been applied to the whole of the somatic musculature. In conformity with the results obtained by previous investigators (Hering, 1893 ; Weiss, 1936) we found that de-afferentation of either one or two limbs did not substantially affect the co-ordinated, diagonal pattern of limb movements. When three limbs were de-afferentated the ambulatory activity of the animal was substantially reduced; nevertheless, the diagonal co-ordination of the limbs was maintained whenever movement occurred. When four limbs were de-afferentated, ambulation was laboured and restricted to a few steps at a time. On the other hand, when de-afferentation was applied to all the spinal nerves II–XI (inclusive) no trace of ambulatory rhythm or of diagonal limb movements was observed, although non-ambulatory responses were obtained from the limbs by labyrinthine or optical stimulation. From these observations we were unable to derive any positive support for the theory, advocated by Weiss (1936), that the power to maintain rhythmical ambulatory limb movements is an intrinsic property of the central nervous system and fundamentally independent of the peripheral sense organs. We see no reason to amend our views, but further consideration is desirable in view of the subsequent publications by Weiss (1941 a, b) which not only stress the conception of an inherent central nervous control of ambulatory rhythms but quote our experiments in its support.
The Co-Ordination of Limb Movements in the Amphibia
Authors: Gray J. , Lissmann H. W. 
Published: April 2021

ABSTRACT
Well-defined myotactic reflexes (retractor-extensor thrusts) can be elicited from the retractor and extensor musculature when these muscles contract against an external resistance. A de-afferentated limb cannot exert a retractor-extensor thrust. A retractor-extensor thrust arising in a forelimb evokes an extensor response in the diagonal hindlimb and a protractor response in the contralateral forelimb. In order that these responses should display themselves with regularity it is necessary to de-afferentate the responding limb; in an intact limb they are often masked by the control exerted by the limb’s own proprioceptive mechanism. In an intact animal a retractor-extensor thrust in a forelimb evokes a ‘placing reaction’ from the ipsilateral hindlimb. This phenomenon is only partially displayed if the hindlimb is de-afferentated. When an intact forelimb responds, by protraction, to passive stretch, the contralateral hindlimb flexes and the ipsilateral hindlimb extends if the latter limbs have been de-afferentated. The individual proprioceptor limb responses integrate to form an adequate picture of the co-ordinated limb movements seen when an intact toad ceases to swim and begins to walk on land. The role of proprioceptor activity in the maintenance of an ambulatory rhythm in a single limb is discussed.
The Neurological Basis of the Locomotory Rhythm in the Spinal Dogfish (Scyllium Canicula, Acanthias Vulgaris)
Authors: Lissmann H. W. 
Published: April 2021

ABSTRACT
Body and fin reflexes in the spinal dogfish, Scyllium canicula and Acanthias vulgaris, are described. A reflex posture can be induced in inactive spinal preparations through localized exteroceptive stimuli. The location of the primary and secondary contraction areas is determined by the site of stimulation. Spinal preparations of Scyllium canicula and Acanthias vulgaris display a persistent locomotory rhythm as long as they are free from contact. Diffuse touch to the ventral surface of a spinal preparation has an inhibitory effect on the swimming movements. Some dogfish remain immobile after the ventral contact has been discontinued, but resume their persistent swimming after application of a gentle exteroceptive stimulus of short duration. Through feeble transitory stimuli any individual swimming stroke can be retarded, temporarily arrested, reversed, accelerated and augmented. The reaction depends on the site of the stimulation and on the momentary phase of the swimming movement at which it is applied. The rhythm emerging after the application of a transitory stimulus is, as a rule, out of phase with the rhythm as recorded prior to the application of the stimulus. Therefore the response cannot be interpreted as resulting from a super-position of an independent automatic rhythm integrating with a reflex, but must be considered as an interaction of two equal and mutually dependent processes.
The Neurological Basis of the Locomotory Rhythm in the Spinal Dogfish (Scyllium Canicula, Acanthias Vulgaris)
Authors: Lissmann H. W. 
Published: April 2021

ABSTRACT
Some of the more striking effects of de-afferentation in the spinal dogfish are diagrammatically represented in Fig. 13.
The persistent locomotory rhythm of a spinal dogfish depends upon afferent excitation. If all afferent excitation is cut off by severance of all dorsal roots, the rhythm is abolished (Fig. 13, 1). The rhythm clearly emerges when about half the number of all the dorsal roots is transected, irrespective whether the anterior or the posterior half of the animal be de-afferentated (Fig. 13, 2 and 3), or whether complete unilateral de-afferentation is executed (Fig. 13, 4). Extensively de-afferentated preparations may exhibit swimming movements after exteroceptive stimulation. These swimming movements do not persist. Preparations de-afferentated except for the tail exhibit after exteroceptive stimulation a static reflex posture. The de-afferentated musculature takes part in both tonic and rhythmic responses as long as it is connected through the spinal cord with normally innervated musculature. In response to electrical stimulation applied to the cord of a spinal dogfish two distinct types of rhythmic response have been evoked. No rhythmic responses have bee obtained through electrical stimulation of the spinal cord in completely de-afferentated preparations. No evidence has been found in support of the view that the swimming rhythm emanates through a spontaneous, automatic activity from the central nervous system.
The Mechanics of Amphibian Locomotion
Authors: Barclay Oliver R. 
Published: April 2021

ABSTRACT
A new type of apparatus is described for measuring the forces exerted on the ground by tetrapods in three orthologonal axes simultaneously. From results obtained with toads and newts an analysis of the mechanics of normal amphibian walking is carried out and several features of Gray’s (1944) analysis of the mechanics of the tetrapod skeleton are confirmed. The introduction into the stride of periods of instability is shown to be related to an increase of the length of the stride and is an adaptation to faster movement. The pattern of couples exerted on the limbs by the extrinsic muscles is calculated for the toad and newt. This is found to be basically the same as that in the cat and in man is shown to be, in several important respects, the most efficient possible. The internal mechanics of the toad forelimb is discussed. It is basically similar to that of both fore- and hindlimbs of the newt. The operation of this type of limb is compared to that of a ‘crank’ mechanism and differs in important respects from that of the mammals.
An Isolated Nerve-Muscle Preparation from Ascaris Lumbricoides
Authors: Baldwin Ernest , Moyle Vivien 
Published: April 2021

ABSTRACT
A technique is described for the preparation from the body wall of Ascaris of semi-isolated strips of muscle. These strips are exposed on one side to the surrounding medium and are suitable for studies of the action of anthelminthic and other drugs upon the exposed musculature. A medium suitable for use in such experiments has been devised and its preparation is described. Media made up to represent the body fluid of Ascaris fail to support physiological activity in the exposed muscle strips, and it seems that this perienteric fluid does not correspond to the true milieu intérieur of this nematode. Some new observations on the nature and composition of the perienteric fluid are presented incidentally in the text.
Disk-Sphere Transformations Produced by Lysins, and Their Reversal, in Systems of Different pH
Authors: Ponder Eric 
Published: April 2021

ABSTRACT
Although sphering almost always occurs at some time before a mammalian red cell haemolyses, the shape change has to be placed in a variable position on the time scale to which the progress of the lytic reaction is referred. In the case of some lysins, e.g. saponin, the shape change is a late event, while in the case of others, e.g. sodium tetradecyl sulphate, it is an early event on the same time scale. In the case of four lysins (sodium taurocholate, sodium tetradecyl sulphate, saponin and digitonin) the amount of lysin required for complete haemolysis increases with increasing pH, but the amount required to produce sphering decreases with decreasing pH. Serum albumin produces a reversal of the disk-sphere transformation brought about by distearyl lecithin, sodium taurocholate, sodium tetradecyl sulphate, saponin and digitonin. Benzene has a weak reversing effect when the spheres are formed as the result of the action of the first three substances mentioned, and cholesterol produces reversal of the shape change only when it is brought about by sodium tetradecyl sulphate. The simple explanation that the reversing agents act by reacting with the lysins and reducing their concentration is not tenable, and the effect of the reversing agents must be regarded as something distinct from their inhibitory effect on the lysin in the system. Some of the substances used can produce the disk-sphere transformation and can even bring about lysis when they are present in such small amounts that they cannot cover the red cell surface. Either the effects produced by each molecule of sphering agent or lysin extend to neighbouring regions on the cell surface and perhaps also into the interior, or sphering and lysis occur as the result of changes at spots on the surface.
Studies in the Development of the Rainbow Trout (Salmo Irideus)
Authors: Smith Sydney 
Published: April 2021

ABSTRACT
The wet and dry weights of a selected population of rainbow trout eggs were determined at intervals from the 1st day after fertilization until the 84th day of incubation at 10° C. The alevin attains its maximum weight at the 65th day, the embryo some 10 days later. The heat production of egg and alevin rises until the 65th day and subsequently fluctuates violently. Fuel values of yolk and embryo samples were measured. The heat production is commensurate with the loss in the total fuel value of the system. Nitrogen excretion of eggs and alevin rises steadily throughout development. It seems probable that only the ammonia fraction is freely diffusible through the chorion. Determinations of the total nitrogen content of embryo and yolk samples demonstrate that the nitrogen excretion observed is sufficient to balance the loss in total nitrogen of the system. The fuel values and excretion measurements are shown to be in accord with the observed loss of dry materials by the egg-alevin system. The significance of this is discussed.
Physiological demands and nutrient intake modulate a trade-off between dispersal and reproduction based on age and sex of field crickets
Authors: Treidel Lisa A. , Clark Rebecca M. , Lopez Melissa T. , Williams Caroline M. 
Published: April 2021

ABSTRACT
Animals adjust resource acquisition throughout life to meet changing physiological demands of growth, reproduction, activity and somatic maintenance. Wing-polymorphic crickets invest in either dispersal or reproduction during early adulthood, providing a system in which to determine how variation in physiological demands, determined by sex and life history strategy, impact nutritional targets, plus the consequences of nutritionally imbalanced diets across life stages. We hypothesized that high demands of biosynthesis (especially oogenesis in females) drive elevated resource acquisition requirements and confer vulnerability to imbalanced diets. Nutrient targets and allocation into key tissues associated with life history investments were determined for juvenile and adult male and female field crickets (Gryllus lineaticeps) when given a choice between two calorically equivalent but nutritionally imbalanced (protein- or carbohydrate-biased) artificial diets, or when restricted to one imbalanced diet. Flight muscle synthesis drove elevated general caloric requirements for juveniles investing in dispersal, but flight muscle quality was robust to imbalanced diets. Testes synthesis was not costly, and life history investments by males were insensitive to diet composition. In contrast, costs of ovarian synthesis drove elevated caloric and protein requirements for adult females. When constrained to a carbohydrate-biased diet, ovary synthesis was reduced in reproductive morph females, eliminating their advantage in early life fecundity over the dispersal morph. Our findings demonstrate that nutrient acquisition modulates dispersal–reproduction trade-offs in an age- and sex-specific manner. Declines in food quality will thus disproportionately affect specific cohorts, potentially driving demographic shifts and altering patterns of life history evolution.
Stimulus-dependent learning and memory in the neotropical ant Ectatomma ruidum
Authors: Riveros Andre J. , Entler Brian V. , Seid Marc A. 
Published: April 2021

ABSTRACT
Learning and memory are major cognitive processes strongly tied to the life histories of animals. In ants, chemotactile information generally plays a central role in social interaction, navigation and resource exploitation. However, in hunters, visual information should take special relevance during foraging, thus leading to differential use of information from different sensory modalities. Here, we aimed to test whether a hunter, the neotropical ant Ectatomma ruidum, differentially learns stimuli acquired through multiple sensory channels. We evaluated the performance of E. ruidum workers when trained using olfactory, mechanical, chemotactile and visual stimuli under a restrained protocol of appetitive learning. Conditioning of the maxilla labium extension response enabled control of the stimuli provided. Our results show that ants learn faster and remember for longer when trained using chemotactile or visual stimuli than when trained using olfactory and mechanical stimuli separately. These results agree with the life history of E. ruidum, characterized by a high relevance of chemotactile information acquired through antennation as well as the role of vision during hunting.
The Reactions of Pygosteus Pungitius L. to Toxic Solutions
Authors: Erichsen Jones J. R. 
Published: April 2021

ABSTRACT
An apparatus is described in which small fish (Pygosteus pungitius L.) are confined in a horizontal glass tube, half of which is filled with flowing tap water and half with flowing solution. Solution and water are very sharply differentiated, so that the concentration difference the fish encounter is known. The directions of flow can be rapidly reversed in order to check the result. The movements of the fish are recorded for 7-120 min., according to the degree of toxicity of the substance tested. A negative reaction is shown towards 1% ethyl alcohol, 1/10,000-1/5000 chloroform and 0.1-0.4% formalin (% HCHO). High concentrations of these substances may stupefy the fish so rapidly that a pseudo-positive reaction appears. A sharp negative reaction is displayed towards 0.003-0.001N mercuric chloride; at 0.0003 the reaction is delayed, at 0.0001 is indefinite, and at 0.00004N solution, though of comparatively high toxicity, does not appear to be detected. Zinc sulphate appears to be detected and avoided at concentrations at least as low as 0.0003N. This concentration is of comparatively low toxicity and may be exceeded in streams polluted by effluents from zinc mines. Copper sulphate is only detected and avoided at extremely high concentrations (0.1N). At 0.04N the reaction is vague, and at 0.01-0.001N the fish swim into the solution where they become stupefied and lie motionless, so that the reaction appears positive. Copper salts appear to impair or destroy the stickleback’s ability to distinguish other toxic substances.
Distribution of Glycogen in the Developing Salmon (Salmo Salar L.)
Authors: Daniel R. J. 
Published: April 2021

ABSTRACT
The presence of glycogen has been recorded in the eggs and larvae of teleosts as a result of histochemical methods, notably by Pasteels & Léonard (1935), who included the fertilized eggs of trout (Salmo irideus) in material used to test the efficacy of various fixatives. They reported glycogen in the blastodisc of the trout egg.
Seasonal Cyclical Changes in the Thymus of the Mallard*
Authors: Höhn E. O. 
Published: April 2021

ABSTRACT
In the course of an investigation into seasonal changes in the endocrine organs of wild mallards (Anas platyrhinchas p. (L.)), a striking seasonal cycle was found in the thymus affecting both the amount of thymus tissue and its histological structure. This appears to be the first description of changes of this nature affecting the thymus apart from a statement by Jolly (1913) in connexion with age involution of the thymus in fowls, to the effect that this tissue is much influenced by seasonal and nutritive changes. Aimé (1912) has described a seasonal regeneration of the thymus in turtles, but it will be shown below that this must be regarded as a different type of response from that found in the mallard.
Studies on Sterility and Prenatal Mortality in Wild Rabbits
Authors: Rogers Brambell F. W. , Mills Ivor H. 
Published: April 2021

ABSTRACT
The relation of the proportion of litters showing loss to the proportion of embryos lost is discussed and is shown to vary according to the way in which the mortality is distributed. The proportion of ova lost before implantation in litters that survive varies according to the number of ova ovulated as the linear regression where x = the initial number of ova in the litter. The loss of ova before implantation in the whole sample of 12,551 ova was 1188 or 9·5%. The proportion of litters suffering loss before implantation in which some embryos survive implantation varies according to the number of ova ovulated as the linear regression where x = the initial number of ova in the litter. The number of litters suffering loss before implantation in which some embryos survive implantation in the whole sample of 2179 litters was 796 or 36·5%. Fewer litters suffered more loss than would be expected if the loss were distributed at random amongst the ova. The sample of litters showing loss is not homogenous, and the probability of loss of ova is greater in some of them than in others. In litters that suffer a loss of two or more ova there is a tendency for the loss to be concentrated in one uterus of each pair. Some or all of this tendency may be accounted for by obstruction of the uterine tract on one side. The number of animals out of a total of 2073 which had lost all the ova on one side, but not on the other, was 92, an excess of 18, or 1·8%, over the expectation on a random basis. The occurrence of loss on one side does not affect the probability of loss on the other side. Not more than 3·64% of litters are lost entirely before implantation and probably not less than 1·00%. The percentage of litters lost entirely before implantation is at a minimum in litters of an initial size of five or six, the most frequent sizes, and at a maximum for litters of the largest and smallest sizes. It is also at a minimum during the height of the breeding season, and is higher at the beginning and end. Animals above the average body weight suffer less loss of ova before implantation in litters that survive than do those below the average body weight. There is no detectable seasonal variation in the loss of ova before implantation in litters that survive. The loss of ova before implantation in litters that survive is heavier in animals with no milk in the mammary glands than in those with milk.
The Effect of Labyrinthectomy on the Co-ordination of Limb Movements in the Toad
Authors: Gray J. , Lissmann H. W. 
Published: April 2021

ABSTRACT
If the limbs of an animal are to propel the body along a straight horizontal line the propulsive forces exerted by the right and left pairs of limbs must be equal and the vertical thrusts exerted by each of the four limbs must be such that their combined resultant is equal to the weight of the body and act through its centre of gravity (Gray, 1944). During the normal ambulation of a toad these conditions are not strictly fulfilled, for the body exhibits a slight but definite tendency to rotate about its principal axes (Barclay, 1946). Since all such movements are liable to induce compensatory reflexes of labyrinthine origin, it is of interest to know how far the normal level of co-ordination between the limbs is affected by labyrinthectomy. In all cases the operation has been performed from the dorsal side.
The Influence of Temperature and Humidity on Instar Length in Calandra Granaria Linn
Authors: Eastham L. E. S. , Segrove F. 
Published: April 2021

ABSTRACT
In an earlier paper, Eastham & McCully (1943), the results of an investigation into the effects of temperature and humidity on the oviposition responses of Calandra granaria were published. There the effects of environment on the multiplication of cultures of Calandra were recorded in so far as that increase depended upon the rate of egg-laying, number of eggs laid and the length of ovipository life of females. An attempt is made here to extend that information, not only by showing how environment determines the total duration of a developmental period, but how it affects each separate instar of that period from the egg to the emergence of the adult from the pupa.