bluuebunny/crossref_metadata_2025_split huggingface dataset:
Territorial Behaviour in Barnacle Settlement
Authors: Crisp D. J. 
Published: April 2021

ABSTRACT
An analysis of the natural pattern of settlement of barnacles, whether arranged along a groove or over a plane area, shows that later settlers tend to maintain a distance of about 2 mm. from earlier ones. This phenomenon in a sedentary form is analogous to territorial behaviour in active species. A method is described which gives average values for population density as a function of the distance from any reference individual. It is found that the reference individual lies in a trough of very low population density, and that the latter rises sharply a short distance away. The distance from the reference individual, at which the population density reaches the average value for the whole population, is defined as the territorial separation. The territorial separation is reduced, but not entirely eliminated, as the population density rises. The value of territorial separation is a little greater than the sum of the radius of the previously settled spat and the length of the cyprid, and is slightly smaller in species with smaller cyprids and spat. Cyprids settle at the periphery of the base of detached specimens rather than at the centre. Though strongly attracted to pits in the surface, cyprids continue to behave territorially within a pit, and avoid pits containing previously settled individuals. They settle readily in pits with only the bases of detached individuals present. Observations on settling cyprids show that after encountering settled barnacles they tend to remain and explore the surface. If they continue to encounter settled individuals at the time they are about to settle, the period of final searching is prolonged until they find a suitably vacant area. Territorial behaviour is probably an adaptation allowing the recently metamorphosed cyprid time to establish itself before it touches the growing edge of another barnacle.
The Structure and Function of the Prothoracic Spine of the Desert Locust, Schistocerca Gregaria Forskål
Authors: Fraser Rowell C. H. 
Published: April 2021

ABSTRACT
The prothoracic sternal spine of Schistocerca is described. The second paired nerve innervates the sensilla of the sternum, coxae, and femora, and in subimaginal stages supplies chordotonal organs registering movement of the cervical membrane. Each nerve fibre serves the axons of several sensilla. When the sensilla are waxed, control of the legs is disturbed. When the prothoracic ganglion is isolated from the CNS stimulation of the sensilla produces complex, oriented, reflex cleaning movements by the legs. Recordings were made from nerve 2 and from the commissures. Co-ordination is mainly segmental; the signal in the commissures is much reduced. At normal levels of stimulation there is no activity in nerve 2 unless several sensilla are excited. Among related genera there is some correlation between manipulative ability and the number of sensilla on the spine. It is suggested that these sensilla contribute to the co-ordination of movements of the front legs.
The Central Nervous Control of Flight in A Locust
Authors: Wilson Donald M. 
Published: April 2021

ABSTRACT
The co-ordination of the flight movements of Schistocerca gregaria Forskål was examined in order to determine the extent of central patterning and reflex control. Electrical recordings from wing sensory nerves showed many units which responded to wing movements of various kinds. During flight the sensory discharge was timed to certain phases of the wing-beat cycle. Surgical removal of the sources of timed input did not abolish patterned output, which resembled that during flight, but the frequency of cycling was considerably reduced. Either electrical stimulation of the nerve cord or continuous wind on the head could elicit the pattern. A multiplicity of oscillators in the flight control system was demonstrated. It is suggested that the basic co-ordination of flight is an inherent function of the central nervous system but that peripheral feedback loops influence the frequency of operation and details of pattern.
Repetitive Potentials Following Brief Electric Stimuli in a Hydroid
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
Electrical pulses (amplitude −0·05 to −15 mV.; duration 20−120 msec.) have been recorded from the stolon of Cordylophora lacustris following stimulation. These pulses are propagated with an average velocity of 2·7 cm./sec. at 22°C. Brief electric shocks of little more than threshold intensity can evoke bursts of pulses. The number of pulses in a burst increases with stimulus intensity, but the shape and size of individual pulses do not. Repetitive stimulation causes facilitation of both size of single pulses and number of pulses in a burst. Refractory period, if present, is variable. The minimum interval between two pulses is about 200 msec. Mechanical stimulation evokes pulses identical to those evoked by electrical stimulation. The greater the number of pulses recorded in the stolon near a polyp, the greater and faster is the contraction of that polyp. The number of pulses, but not their individual sizes, decreases with increasing distance from the point of stimulation. It is concluded that conduction in the stolon and the electrical pulses are due to nervous activity and that the conducting system is a network having intemeural junctions which sometimes require to be facilitated.
The Movements of Sodium Ions in the Isolated Abdominal Nerve Cord of the Cockroach, Periplaneta Americana
Authors: Treherne J. E. 
Published: April 2021

ABSTRACT
The rate of loss of sodium ions from the abdominal nerve cord of Periplaneta has been determined by following the decline in radioactivity of 24Na-loaded nerve cords isolated in flowing Ringer solution. In all of the experiments there was an initial rapid exponential decline in radioactivity which eventually gave way to a second slower phase. The initial exponential extrusion of sodium ions was appreciably reduced by the presence of potassium cyanide and 2:4-dinitrophenol. The rate of sodium efflux was not reduced in sodium-free solutions, but was decreased in the absence of external potassium ions. It is concluded that sodium ions are extruded from the nerve cord by a metabolically maintained secretory mechanism which is also associated with the uptake of potassium ions.
Osmotic Regulation in the Crab-Eating Frog (Rana Cancrivora)
Authors: Gordon Malcolm S. , Schmidt-Nielsen Knut , Kelly Hamilton M. 
Published: April 2021

ABSTRACT
The osmotic and ionic regulatory abilities of adults of the euryhaline crab-eating frog (Rana cancrivora) have been studied. Adult frogs tolerated environmental salinities as high as 28%,, at 30°C. Tadpoles of this form tolerated salinities as high as 39 % at the same temperature. Changes in body weight of frogs following transfers to different environmental salinities indicate both that the skin of this frog is permeable to water and that these animals do not swallow large volumes of external medium, even in high salinities. Above salinities of about 9 %, plasma Δrises with increasing environmental Δ. Plasma Δ is always higher than environmental Δ. Increases in plasma concentration above fresh-water levels are due partly to increased NaCl concentration (about 40%), partly to increased urea concentration (about 60%). Urea concentrations as high as 0·48 M (2·9%) have been measured. Urinary A parallels plasma Δ, but is always lower than plasma Δ. Considerable quantities of urea are lost via the urine, even though urinary urea levels are below plasma levels. Measurements of short-circuit current indicate that active uptake by the skin of inorganic ions continues in R. cancrivora acclimatized to high salinities. R. cancrivora is no less susceptible to water loss by evaporation from the skin than are other amphibians. In preference experiments R. cancrivora chooses salinities below 18 %, but shows no strong preference for a particular salinity. Similar observations on osmoregulatory mechanisms in a close relative of R. cancrivora, the tiger frog (R. tigerina), show that the latter species is similar to ordinary fresh-water frogs. The striking physiological convergence between R. cancrivora and the elasmobranch fishes is discussed, as are various possible implications of our data regarding nitrogen metabolism in tadpoles and kidney function in adult frogs.
The Swimming Response and Its Pacemaker System in the Anemone Stomphia Coccinea
Authors: Robson Elaine A. 
Published: April 2021

ABSTRACT
The swimming behaviour of the anemone Stomphia coccinea Müller has been described by several authors (Stephenson, 1935; Yentsch & Pierce, 1955; Sund, 1958; Wilson, 1959; Hoyle, 1960; Robson, 1961). Specimens from the region of Puget Sound and the San Juan Islands respond to contact with certain starfish or to suitable electrical stimulation with a characteristic sequence of activity. They retract, re-expand, detach from the substratum, and display a series of abrupt bending movements which may continue for several minutes. An inert recovery period is followed by re-attachment to the substratum. The only species so far known to provoke this response are the starfish Hippasteria spinosa Verrill and Dermasterias imbricata Grube. The world distribution of the genus Hippasteria overlaps to some extent that of Stomphia, which is a widespread North European-Arctic form, but Dermasterias is strictly indigenous to the north-west American coast. Neither starfish seems to affect the anemone in any other way, and the significance of this particular response is difficult to understand.
The Mode of Excretion of Ammonia and Urea in Xenopus Laevis
Authors: Balinsky J. B. , Baldwin E. 
Published: April 2021

ABSTRACT
Eighty-two single determinations of ammonia and urea excretion by Xenopus laevis indicated that the percentage of ammonia varied from 40 to 80%, with a mean value of 62%. Measurements of excretion on successive days after feeding showed that a large amount of ammonia was produced soon after feeding, but that ammonia excretion declined rapidly. Urea excretion, not so high initially, remained more or less constant until the third or fourth day, often exceeding ammonia excretion at that time. Thereafter, it also declined and the excretion of both substances reached a constant starvation level by the fifteenth day. Both ammonia and urea excretion were equally affected by temperature. The Q10’s were near 2 in the range 20–30° C., but greater in the range 10–20° C. At least 86% of ammonia, and 8r % of urea were excreted through the cloaca. The mean 24 hr. urine output of Xenopus at 20° C. was 23·6 ml. per 100 g. body weight. Although the blood ammonia concentration did not appear to be zero, the urine/blood concentration ratio of ammonia was greater than 100. The urine/blood concentration ratio of urea was not significantly different from unity, and constant over a very wide range of concentrations. The above result is interpreted to indicate passive glomerular filtration of urea, and little or no tubular reabsorption of water. It is suggested that ammonia is formed in the kidney, and actively secreted into the glomerular filtrate.
Visco-Elastic Properties of the Tunica Externa of the Swimbladder in Cyprinidae
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
The tunica externa of the anterior sac of the swimbladder in Cyprinidae is highly extensible, but a large part of its compliance is associated with retardation times greater than one second. The compliance is only partly reversible. The significance of these properties is discussed in relation to a possible high-pass frequency filter for the Weberian apparatus.
Pharmacological Studies on the Auditory Synapses in A Grasshopper
Authors: Suga Nobuo , Katsuki Yasuji 
Published: April 2021

ABSTRACT
Picrotoxin, eserin, butyrylcholine and acetylcholine bring about increase of impulse discharges on the T large fibre in the cord. Picrotoxin gives conspicuous increase of impulse discharges in the response of the T large fibres to sound, while the excitatory effects of the latter three agents are not so conspicuous. Such effects can be explained on the assumption that picrotoxin inhibits the inhibitory synapses, so that the T large fibre is fully activated by both tympanic nerves, while the latter three agents activate both the excitatory and inhibitory fibres. GABA, γ-aminobutyrylcholine and D-tubocurarine act reversibly as inhibitors of the activity of the T large fibre. The response evoked in the T large fibre may be suppressed by the activities of the inhibitory interneurons activated by the tympanic nerve fibres. After the application of picrotoxin solution to the prothoracic ganglion the threshold of the T large fibre near to a sound source rises while that of the opposite side falls. The inhibitory effect seems to be eliminated by the drug action and the T large fibre is activated by both the ipsilateral and the contralateral excitatory fibres. The increased information about a source of sound which arises from the central inhibitory interaction is disturbed by the application of picrotoxin. The conclusion that the T large fibre has excitatory synapses with the tympanic nerves, and inhibitory synapses with the inhibitory interneurons activated by the tympanic neurons, has been confirmed pharmacologically. The inhibitory interneurons are activated not only by the natural activity of the tympanic nerve, but also by activity elicited electrically with square pulses.
The Cells Founding Aggregation Centres in the Slime Mould Polysphondylium Violaceum
Authors: Shaffer B. M. 
Published: April 2021

ABSTRACT
In an ordinary agar-plate culture of the collective amoeba, or cellular slime mould, Polysphondylium violaceum, the solitary phase ends when compact and increasingly refractive cell clumps develop among the unoriented cells and secrete the chemotactic factor acrasin. Neighbouring cells may crawl towards them, either singly or aggregated in streams, which relay chemotactic and contact guidance centrifugally (Shaffer, 1957a, 1958). As already briefly reported (Shaffer, 1959), aggregation centres may be started by single, differentiated cells ; these have been called founders.
On the Regulation of Respiration in Reptiles
Authors: Nielsen Bodil 
Published: April 2021

ABSTRACT
The chemical regulation of respiration in various species of reptiles has earlier been studied by Siefert (1896), Babak (1914a, b), v. Saalfeld (1934), Vos (1936), Boelaert (1941,1942), Randal, Stullken & Hiestand (1944), and B. Nielsen (1961). A survey of the literature was given by Vos (1936).
The present work deals with the effect of different concentrations of O2 in the inspiratory air on respiration of lizards. Further, the combined action of CO2 and different O2 percentages has been studied. Two species of lizard, Lacerta viridis and Tarentola mauretanica served as experimental animals.
The Response of the Ampullae of Lorenzini of Elasmobranchs to Electrical Stimulation
Authors: Murray R. W. 
Published: April 2021

ABSTRACT
The ampullae of Lorenzini are sensitive to weak electrical stimuli which presumably cause currents to flow along the jelly-filled tubes of the sense organ. Increase of the resting frequency occurs when the tube-opening is made negative to the capsule, and inhibition when the opening is positive, with opposite after-effects in each case. Adaptation is three-quarters complete in about 5 sec. When the stimulus is applied as a voltage gradient in the water overlying the ampullae, the threshold for the most sensitive units is 1 μV./cm., which represents a current along the tube of less than 5 ×10−11 A. When the stimulus is applied as a current directly to the tube opening, the threshold for the most sensitive units is 4 ×10−10 A. Changes in the salinity of the water at the tube opening are also effective, the threshold being about 3 %. Dilution causes excitation, and concentration causes inhibition. The response is not due to the osmotic differences, and so probably results from potentials established at the jelly-water interface.
Studies on Chitin Synthesis in the Desert Locust
Authors: Candy D. J. , Kilby B. A. 
Published: April 2021

ABSTRACT
In vivo studies on 5th instar and adult locusts revealed that chitin formation in thorax, abdomen, hind leg and wing was greatest during the first few days after moulting. Wing extracts were used for in vitro experiments, and evidence was obtained for the presence of the following enzymes: hexokinase, phosphohexose isomerase, glutamine transaminase, phosphoglucosamine transacetylase, acetyl coenzyme-A synthetase, phosphoacetylglucosamine mutase and uridine diphosphate N-acetyl-glucosamine pyrophosphorylase. The results are discussed, and a tentative scheme is presented for the biosynthesis of chitin in the wing of Schistocerca gregaria.
Evidence For the Intraocular Discrimination of Vertically And Horizontally Polarized Light by Octopus
Authors: Moody M. F. 
Published: April 2021

ABSTRACT
Four groups of octopuses (6 animals in all) were trained to discriminate between vertically and horizontally plane-polarized light. Two different sources of polarized light were used: a torch, and a disk of polaroid backed by white plastic. Half the octopuses were trained using the former source, and half using the latter. With each polarized light source, discrimination could be based on a reflexion or scattering pattern, but the extra-ocular cues would be different for the two sources. After training, each octopus was shown, without reward or punishment, the polarized light source with which it was not trained. The aggregate score shows efficient transfer, and three of the four groups showed a significant preference for the new source when the plane of polarization was the same as that which they were trained to attack. It is concluded that the discrimination is not based on extra-ocular patterns, i.e. that the analysis of the polarized light occurs within the octopus’s eye.
Proprioceptive Reflexes In The Legs Of Carcinus Maenas (L.)
Authors: Bush B. M. H. 
Published: April 2021

ABSTRACT
The reflex responses of the motor and inhibitor axons of the four distal muscles in the thoracic limbs of Carcinus maenas to passive movements of the dactylus and propus in the same limb are described.
Passive ‘opening’ (extension of the dactylus), both at steady speeds and in a stepwise manner, elicits a strong reflex discharge in the inhibitor axon specific to the opener muscle and in the ‘slow’ motor axon to the closer muscle. Passive ‘stretching’ (re-duction of the propus) evokes similar responses in the specific inhibitor axon of the stretcher muscle and in the ‘slow’ motor axon of the antagonistic bender muscle. Rapid opening (or stretching), in a fresh preparation, also excites the ‘fast’ motor axon of the closer (or bender) muscle. During passive closing or bending (propus pro-duction), the motor axon which innervates both opener and stretcher muscles discharges. No activity was observed in any of the branches of the ‘common inhibitor’. The frequencies of discharge of the two ‘slow’ motor axons and the two inhibitor axons during opening and stretching do not vary with displacement at constant speeds, at least within the range of speeds used (10–5oo° /sec.). Frequencies of 1060 impulses per second are common in these axons. The response frequency of the opener-stretcher motor axon during closing, however, and to a lesser extent during bending, increases with displacement at the lower speeds (10–100° /sec.). For all these axons, but in particular for the ‘slow’ motor axons and also the nhibitor axons, the frequency of discharge increases with speed of movement. The reflex responses to dactylus movement vary with the position of the propus, whether stretched, median or bent, in a way which indicates that the separate specific inhibitor axons to the opener and stretcher muscles do make independent action of these muscles possible, despite the fact that both muscles are supplied by one and the same motor axon. The reflex responses to opening and closing can be separately abolished by cutting the requisite one of the two groups of afferent fibres leaving the ‘FD-organ’. Elimination of the receptor organ ‘CP1’ abolishes all reflex response to stretching, and ‘CP2’ elimination abolishes the reflex responses to bending.
These proprioceptive motor and inhibitor ‘resistance reflexes’ are discussed in relation to control and co-ordination of the propo-dactylopodite (PD) and carpopropodite (CP) joints, and to the types of afferent fibres involved.
The Composition of the Seminal Plasma of Balanus Balanus
Authors: Barnes H. 
Published: April 2021

ABSTRACT
Studies of a small number of mammalian species, a few common fishes, and to a lesser extent some echinoderms, have provided much of the available data on the biochemistry of semen: the Crustacea have hardly been investigated. The present work is part of a study of the physiology and biochemistry of reproduction in the Cirripedia, particularly in relation to the ecology of this group.
Visco-Elastic Properties of the Body-Wall of Sea Anemones
Authors: Alexander R. McN. 
Published: April 2021

ABSTRACT
Creep of narcotized Metridium and Calliactis body-wall at constant tensile stress has been studied quantitatively. It was found to be reversible, and seemed to be controlled by the mesogloea. Its course could be represented by equations of the form where the retardation time τ was about 1 hr. for Metridium and many hours for Calliactis. The results can most simply be explained in terms of a cross-linked and a noncross-linked polymeric system, acting in parallel. An explanation in terms of a lattice of inextensible fibres is not satisfactory. The results are discussed in relation to the behaviour of the animals.
The Imaginal Ecdysis of Blowflies. Observations On the Hydrostatic Mechanisms Involved in Digging and Expansion
Authors: Cottrell C. B. 
Published: April 2021

ABSTRACT
The digging movements and the expansion process of newly emerged blowflies involve the production of positive internal pressures. During digging newly emerged blowflies produce a characteristic cycle of internal hydrostatic pressure changes which in Sarcophaga reach, at their maximum, 6 – 12 cm. of mercury. During expansion, two different pressure phenomena are detectable. First, there is a gradual rise and fall in the basic haemolymph pressure which reaches a maximum (of 6 cm. of mercury in Calliphora and 9-5 cm. in Sarcophaga) a few minutes after full wing extension and then falls to atmospheric pressure in the next 20 min. Secondly, superimposed on the basic rise there is a series of brief rhythmic pressure pulses which gradually decline and then cease about the time of full wing extension. Evidence obtained by blocking the proboscis or denervating the abdominal muscles of newly emerged flies indicates that the gradual rise in haemolymph pressure is attributable to air-swallowing and the pressure pulses to the performance of ‘muscular efforts’ (i.e. simultaneous contractions of both the ptilinal and abdominal muscles). The wing expansion of flies which have had their abdominal muscles denervated is abnormal, suggesting that at least some of these muscles play a part in bringing about normal expansion. After full wing extension has occurred (or after an operated fly has reached a point in the air-pumping cycle at which expansion would have occurred) ‘muscular efforts’ cease and digging movements can no longer be stimulated. This cessation is not due to the hardening of the cuticle and it is suggested that it is due to loss of the ability to excite the muscles concerned. Within a few days of emergence many (perhaps all) of the muscles concerned in the production of digging movements and ‘muscular efforts’ degenerate. Immediately after expansion flies eliminate large quantities of fluid via the anus. This appears to be correlated with the change from a combined hydrostatic and external skeleton to a hard exoskeleton.