bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maximum Load-Lifting and Induced Power Output of Harris’ Hawks are General Functions of Flight Muscle Mass
Authors: Marden James H. 
Published: April 2021

ABSTRACT
Pennycuick et al. (1989) recently reported results of an experiment in which climbing rate and load-lifting ability were measured for two trained Harris’ hawks (Parabuteo unicinctus Audubon) flying with various amounts of experimentally applied loads. These data were used to estimate climbing power, maximum aerodynamic power output, and performance consequences of loads in the form of radiotracking equipment.
Effects of Intranasal Application of the Local Anaesthetic Xylocaine on Vestibulo-, Opto-Collic and Postural Reflexes of the Head, and on Tonic Immobility in Homing Pigeons: Implications for Experiments on Pigeon Homing
Authors: Dornfeldt K. , Bilo D. 
Published: April 2021

ABSTRACT
Spraying lidocaine (Xylocaine), a local anaesthetic, into the nasal cavity of homing pigeons is a technique widely used to study the role of olfaction in pigeon homing. Studies in the laboratory revealed that Xylocaine suppressed vestibular and optokinetic nystagmus, roughly for as long as it suppressed olfaction, interfered with control of the head posture when the body was tilted in the sagittal plane, and prolonged tonic immobility. Amplitude and duration of both optokinetic and vestibular nystagmus were affected to the same extent. The effects are most probably caused by the drug’s rapid absorption via the mucous membranes in the nasal cavity and its transport in the blood to brain structures involved in integrating vestibular and visual inputs. The results provide room for nonolfactory explanations of the manifold effects on pigeon homing following administration of local anaesthetics to the nasal chambers.
Proprioception In Insects
Authors: Pringle J. W. S. 
Published: April 2021

ABSTRACT
The campaniform sensilla on the legs of Periplaneta are similar in action to those on the palps, and respond to strains in the cuticle. They are arranged in groups at the joints, with parallel orientation of the sensilla of a group. Tests with various chemical substances show a complete absence of sensitivity to olfactory stimuli. A theory is given of the mode of action of the sensilla in terms of a mechanical model based on their observed structure. Each group of parallel sensilla should act as a unit, responding to those forces which have a compression component of shear in the direction of their long diameters. This theory makes it possible to predict the behaviour of the sensilla from their anatomical arrangement. Most if not all the groups on the legs are so arranged as to be sensitive to the forces present when the insect is standing on the ground. The sensilla probably provide the basis for the sense of contact pressure postulated by Holst (1935), Hoffmann (1933), Crozier & Stier (1928-9), Fraenkel (1932) and others. Comparison of this proprioceptive mechanism with that of the vertebrate limb reveals an absence of qualitative sensitivity that may have an important bearing on the question of the evolution of behaviour.
The Physiology Of Contractile Vacuoles
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
The rate of output of fluid from the contractile vacuoles of fresh-water peritrich ciliates was reduced in solutions of sulphide of concentration not less than M/1000. This effect was reversible. Cyanide depressed the rate of vacuolar output in a concentration of M/100,000, but was more effective in higher concentrations (M/1000). In cyanide solutions there was (a) either a severe initial check or a temporary stoppage of the vacuole, and then later (b) a partial recovery of the rate of output to a value which was still much below the normal. During the initial check the body swelled. Return of the organism from cyanide solution to tap water was followed by a sharp increase in the rate of vacuolar output to an abnormally high value. The body then shrank gradually to its normal size, and the rate of output also fell slowly to normal. The swelling of the body which followed treatment of the organism with cyanide could be exactly counteracted by the addition of sucrose to the outside medium in a 0·05 M concentration. It is concluded that the normal difference of osmotic pressure across the body surface is equivalent to that of a 0·05 M sucrose solution, and that this difference is maintained by the contractile vacuole. The permeability of the body surface to water is estimated as 0·125–0·25 ubic miera per square micron per atmosphere per minute.
Experimental Studies On The Sexual Cycle Of The South African Clawed Toad (Xenopus Laevis). III
Authors: Bellerby C. W. , Hogben Lancelot 
Published: April 2021

ABSTRACT
Removal of the whole pituitary gland of Xenopus laevis or of the anterior lobe alone is accompanied by (a) reduced food intake, (b) diminished growth of the body as a whole, (c) retrogression of the gonads in both sexes. Since there is no significant reduction in the main fat reserves of the body (corpora adiposa) the retrogression of the gonads is not the direct result of reduced food intake at an all-round lower metabolic level. Since the reduction of food intake is proportionately much greater in females than in males, the metabolic demands of the gonad seems to be the controlling agency of food intake. The relatively greater reduction of growth rate in females is due to the large bulk of the ovaries coupled with the fact that ovarian retrogression accompanies the lowering of growth in the rest of the body. Since the food demand of the active ovary is far in excess of the minimum requisite for body growth, the results of this enquiry provide additional confirmation for the view that seasonal variations of food supply are mainly responsible for seasonal variations in the condition of the ovaries of Xenopus in its natural habitat.
The Biophysics of the Egg Surface of Echinus Esculentus During Fertilization and Cytolysis
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
When an egg is fertilized, well-defined morphological changes occur. In spite of this, physico-chemical differences between fertilized and unfertilized eggs have been difficult to find. Nor have the increases in permeability and metabolic rate found in certain eggs been shown to be of general incidence. Investigations of the electrical properties of eggs are few, and the results have been inconclusive and contradictory.
The Morphogenetic Function of A Vestigial Organ in the Chick
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
The pronephros opposite any given somite in the chick is probably determined just before the early neural plate stage at that level, and thereafter develops independently of the somite or lateral plate mesoderm. The Wolffian duct, which is first formed by the union of the pronephric tubules, grows backwards by the multiplication of its own cells. If this elongation is checked by a transverse cut made posterior to the end of the duct, the duct does not appear behind the cut. In the absence of the Wolffian duct, the mesonephros is not properly developed, appearing only as very small patches of tissue with no lumen. The Wolffian duct may therefore be said to induce the mesonephros, which, however, has a feeble power of self-differentiation as a double assurance. This provides a confirmation of previous suggestions that an organ which is vestigial in the sense that it has lost its physiological function may be retained in ontogeny because it still fulfils the morphogenetic function of providing a stimulus essential for the development of other, physiologically more important, structures.
Sex Hormones and Their Effect Upon Conditioned Responses in the Rudd (Leuciscus Leuciscus)
Authors: Vanderplank F. L. 
Published: April 2021

ABSTRACT
Since the effects of the sex hormones on the fish do not show any sex differences, the results of the experiments on both males and females can be summarized together.
Oestrone inhibited an artificially produced conditioned response. Prolan and progesterone had no effect upon the functioning of the conditioned response, although several or prolonged injections of prolan are likely to cause inhibition due to natural causes, e.g. maturation of ova in oviducts. Progesterone, although foreign to the Pisces, terminates the inhibition brought about by previous injections of oestrone. Death caused by injection of progesterone can be prevented by injection of oestrone.
A Portable Apparatus for the Determination of Oxygen Dissolved in A Small Volume of Water
Authors: Fox H. Munro , Wingfield C. A. 
Published: April 2021

ABSTRACT
In 1888 Winkler published his well-known method for the determination of oxygen dissolved in water. The principle of the method is as follows. A solution of manganous chloride is added to the water to be analysed, followed by a solution of sodium hydroxide containing potassium iodide. A precipitate of manganous hydroxide is first formed thus:
Anterior Pituitary and Growth in the Axolotl (Amblystoma Tigrinum(Green) Neotenic Form)
Authors: Howes N. H. 
Published: April 2021

ABSTRACTA method is described by which the food intake of axolotls during a given period can be compared with their growth during the same period. The method has been applied to animals injected with growth-promoting hormone. The ratio has been calculated for batches of ten axolotls injected with muscle extract, Schockaert’s extract of anterior pituitary, phyone, prolactin (Bates & Riddle, 1935), prolactin plus phyone. This ratio was 2·66 ± 0·20 for animals injected with muscle extract, 1·47 ± 0·12 for Schockaert’s extract, 1·60 ± 0·11 for phyone, 2·21 ± 0·16 for prolactin and 1·68 ± 0·12 for prolactin and phyone together. The effect is attributed to increased nitrogen anabolism.
Studies in Animal Locomotion
Authors: Gray J. , Lissmann H. W. 
Published: April 2021

ABSTRACT
The kinetics of locomotion in the earthworm and the nature of the factors which control the various phases of the ambulatory cycle have been subjects of extensive investigation. Numerous theories have been advanced, but a general survey of the literature suggests that the time has not yet been reached at which the more outstanding observations can be fitted into a relatively precise picture. The observations recorded in this paper are, however, relevant for this purpose.
Anterior Pituitary and Growth in the Axolotl (Amblystoma Tigrinum (Green) Neotenic Form)
Authors: Clements D. I. , Howes N. H. 
Published: April 2021

ABSTRACT
The effects of injection of (a) Schockaert’s extract of anterior pituitary, (b) Van Dyke & Wallen-Lawrence’s phyone and (c) prolactin, upon the growth of larval neotenic Amblystoma tigrinum, have been investigated. The normal growthrate was established before injections were begun and controls were injected with muscle extract. The dosage adopted in all cases was equivalent to 1 mg. of fresh tissue per gram of axolotl per day. This was probably supramaximal. Schockaert’s extract and phyone caused a marked increase in the rate of growth, prolactin a slight increase. Of the ten animals injected with Schockaert’s extract, all except one showed some of the signs usually associated with metamorphosis in A. tigrinum. The other experimental animals did not. In no case were there any abnormal changes in the bodily proportions or in the shape of the skeleton. The growth of half the animals after injections had been stopped was also investigated. In the case of most of the animals injected with Schockaert’s extract or with phyone, there was a loss of weight, followed by recovery and growth in the case of the latter only. The prolactin-injected animals showed no such reaction.
Linear and Nonlinear Encoding Properties of an Identified Mechanoreceptor on the Fly Wing Measured with Mechanical Noise Stimuli
Authors: Dickinson Michael H. 
Published: April 2021

ABSTRACTThe wing blades of most flies contain a small set of distal campaniform sensilla, mechanoreceptors that respond to deformations of the cuticle. This paper describes a method of analysis based upon mechanical noise stimuli which is used to quantify the encoding properties of one of these sensilla (the d-HCV cell) on the wing of the blowfly Calliphora vomitoria (L.). The neurone is modelled as two components, a linear filter that accounts for the frequency response and phase characteristics of the cell, followed by a static nonlinearity that limits the spike discharge to a narrow portion of the stimulus cycle. The model is successful in predicting the response of campaniform neurones to arbitrary stimuli, and provides a convenient method for quantifying the encoding properties of the sensilla.The d-HCV neurone is only broadly frequency tuned, but its maximal response near 150 Hz corresponds to the wingbeat frequency of Calliphora. In the range of frequencies likely to be encountered during flight, the d-HCV neurone fires a single phase-locked action potential for each stimulus cycle. The phase lag of the cell decreases linearly with increasing frequency such that the absolute delay between stimulus and response remains nearly constant. Thus, during flight the neurone is capable of firing one precisely timed action potential during each wingbeat, and might be used to modulate motor activity that requires afferent input on a cycle-by-cycle basis.
Comparison of Encoding Properties of Campaniform Sensilla on the Fly Wing
Authors: Dickinson Michael H. 
Published: April 2021

ABSTRACTThe wing blade of the blowfly Calliphora vomitoria (L.) carries an array of campaniform sensilla which have previously been divided into slowly and rapidly adapting classes based on their responses to step indentations. In the present study, the physiological characteristics of six sensilla of these two classes are examined within a 20–400 Hz frequency range, using a noise analysis that quantifies linear and nonlinear encoding properties. Both classes exhibit a broad response maximum near 150 Hz, corresponding to the typical wingbeat frequency of the blowfly, and display rectification, limiting the spike response to a narrow portion of a stimulus cycle. The similarity in the encoding properties between the two groups is largely a consequence of the high wingbeat frequency of flies, which precludes any individual neurone from acting as a magnitude detector. Instead, during flight the campaniform neurones might act as ‘one-shot’ detectors, firing a single action potential at a precise phase of each wing stroke cycle. An array of such detectors would be capable of monitoring the passage of a deformational wave as it travels along the wing during each wingbeat.
The ventilatory movements of the avian pelvis and tail: function of the muscles of the tail region of the pigeon (Columba livia)
Authors: Baumel J. J. , Wilson J. A. , Bergren D. R. 
Published: April 2021

ABSTRACTWe have observed that birds of several different taxa move their tails in conjunction with sound production. These observations suggested to us that tail movements might also be associated with ventilation. Since we hypothesized that rhythmic movements of the tail and pelvis will ventilate the lungs, the activities of tail, epaxial and cloacal muscles of the pigeon were examined. Electromyograms (EMGs) were recorded from these muscles while ventilation was monitored. A muscle was considered to have ventilatory activity when the EMG activity had an obvious correlation to either inspiration or expiration. To obtain further information about the correlation between muscular activity and ventilation, we induced hyperpnea by administering 5 % CO2. We report that the tail muscles that function as expiratory muscles are the M. caudofemoralis, the M. pubocaudalis internus and the M. pubocaudalis externus. We refer to these as the suprapubic abdominal muscles to distinguish them from the infrapubic (ventral) abdominal muscles. These muscles depress the pelvis and the uropygium and compress the thoracoabdominal cavity. M. transversus cloacae functions as an expiratory muscle by protracting the cloaca or by reducing its compliance. Of the suprapubic muscles we studied, the only inspiratory muscle is the axial muscle, M. longissimus dorsi. M. longissimus dorsi acts at the notarial-synsacral junction to elevate the pelvis. The rocking movements of the notarial-synsacral joint appear to be important for ventilation during conditions in which the sternum is ‘fixed’, such as when the bird is resting on its breast. We suggest that a division of labor may exist between the infra- and suprapubic abdominal muscles during ventilation such as panting or vocalization.
Short Communication The moment of Inertia of Bird Wings
Authors: Kirkpatrick Sean J. 
Published: April 2021

ABSTRACTThe moment of inertia of a wing about its proximal end must be known in order to calculate the inertial torque and power required during flapping flight (Ellington, 1984) and it is also one of the morphological features that affects flapping frequency (Pennycuick, 1975, 1990). At present, however, there are very few data on wing moments of inertia of flying animals and thus there is no way of predicting the wing moment of inertia of a flying animal from easily obtainable morphological measurements. Arguments predicting bird wingbeat frequencies (Pennycuick, 1975), following Hill’s (1950) argument that the maximum frequency of a vibrating limb is set by the mechanical properties of the muscles and tendons that accelerate and decelerate the limb at each end of the oscillation, have assumed geometric scaling of wing moment of inertia about the shoulder joint. The objective of this study was to determine if the wing moment of inertia of birds does indeed scale geometrically or, if not, how it actually does vary with body size.
Synthesis and Transport of Agrin-Like Molecules in Motor Neurons
Authors: Magill-Solc Catherine , McMahan U. J. 
Published: April 2021

ABSTRACT
Several lines of evidence indicate that agrin, or a protein very similar to it, directs the formation and maintenance of the postsynaptic apparatus at the neuromuscular junction. We discuss the results of studies involving immunohistochemical, biochemical and in situ hybridization techniques that support the hypothesis that agrin or agrin-like molecules active at the junction are produced by motor neurons.
The influence of action potentials on the development of the central visual pathway in mammals
Authors: Kalil R. E. 
Published: April 2021

ABSTRACT
The development of the mammalian visual system begins prenatally at distributed sites, where cells generated at different embryonic ages are destined to interconnect and form the visual pathways, and ends postnatally with the functional tuning of neuronal receptive-field properties. It is reasonable to assume that the earliest stages in this developmental sequence are completed prior to the onset of neural activity, and also that activity may play only a minor role or even none at all in primary axon outgrowth and pathway finding (Harris, 1981; Harris and Holt, 1990). However, recent evidence indicates that subsequent events in development, such as the sorting of axons at their targets, the cellular differentiation of target cells and the formation of synaptic contacts by developing axons, are all influenced by action potentials.
Action potentials in the developing retino-geniculo-cortical pathway can be eliminated by blocking the voltage-gated sodium channel with tetrodotoxin. Prenatal blockade prevents the laminar segregation of retinogeniculate axons. Postnatal blockade interrupts the formation of retinogeniculate synaptogenesis, slows the cytoarchitectonic differentiation of the lateral geniculate nucleus and produces abnormalities in the responses of lateral geniculate neurons. In the visual cortex, the development of cells and synapses is retarded and the eye-specific separation of geniculocortical axons is halted, thereby blocking the formation of ocular dominance columns. While the cellular mechanisms underlying these effects are not understood, a partial restoration of normal development can be produced by stimulating blocked axonal pathways electrically.
In vitro experiments on axonal guidance and growth-cone collapse
Authors: Müller B. , Stahl B. , Bonhoeffer F. 
Published: April 2021

ABSTRACT
In the retinotectal projection, nasal retinal axons project to posterior tectum, while temporal axons project to the anterior part of the tectum. In in vitro experiments, a similar specificity can be observed: the nasal and temporal retinal axons can be guided by tectal membrane components so that, for example, temporal retinal axons, when growing on a striped substratum consisting of anterior and posterior tectal membranes, express a very strong preference for the anterior stripes. This preference is not due to attractivity of anterior membranes but rather to avoidance of posterior material, although the pure posterior membranes are a very good substratum for growth of temporal axons. The repellent guidance molecule has been identified. Interestingly, besides guidance this molecule causes another reaction: when growing temporal axons are exposed to medium containing either posterior membranes or artificial lipid vesicles containing the repellent guidance molecule, the axonal growth cones collapse. As in guidance, there is a clear regional specificity: e.g. the repellent guidance molecule derived from posterior tectum induces collapse of temporal but not of nasal axons.
Since the guiding and the collapse-inducing activity are expressed by one and the same glycoprotein molecule (Mr33×103, linked to the membrane by phosphatidylinositol) and since another molecule has been identified by Keynes’ group which also expresses both guiding and collapse-inducing activity, one might speculate that axonal guidance and axonal collapse have something in common. Models of axonal guidance will be discussed.
Positional Discrimination and re-development of Synapses in the Leech Whitmania Pigra
Authors: Zhang Ren-Ji , Zhu Lixia , Wang Dan-Bing , Zhang Fan , Zou Dong-Jing 
Published: April 2021

ABSTRACT
Identified neurones in the leech Whitmania pigra have a stable morphology with bilaterally symmetrical branching arborizations, and with axons on both sides arranged symmetrically in the connectives. Each anterior pagoda cell (AP) receives electrical and/or chemical synaptic input from mechanoreceptive cells on both sides of the body. The position in the body can be discriminated by the postsynaptic responses of the APs: as a rule, the responses to input from contralateral receptive neurones are stronger than those to input from ipsilateral ones, and the neurone with its receptive field on the dorsal side produces a stronger response than the neurone with a ventrally sited receptive field. APs integrate postsynaptic potentials and spikes. There are no connections between the two AP cells and so it is possible that positional discrimination depends upon a circuit comparing the inputs.
After the body wall has been cut round and rotated by 180°, the mechanoreceptive cells and annular erector motoneurones reinnervate the body wall strictly according to their original orientation, and repair is bilaterally synchronous. This eliminates a role for target cell guidance, particularly in the adult leech. When an extra Retzius cell is implanted into cultured ganglia, synapses develop between the host and the implanted neurone. Such synapses generally show lower coupling ratios or PSP fluctuations. However, the specific electrical connection between the Retzius cells shows a normal coupling ratio.