bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Auditory System of Homorocoryphus (Tettigonioidea, Orthoptera)
Authors: McKay J. M. 
Published: April 2021

ABSTRACT
The responses of the auditory interneurones indicate that the tettigoniid ear discriminates frequencies. The T fibre receives strong ipsilateral and weak contralateral excitatory inputs and a strong contralateral inhibitory input, from the tympanic nerves. These inputs are frequency-sensitive, the response being greatest at 30 kcyc./sec. and above. Responsiveness is low in the region of 15 kcyc./sec., which is the dominant song frequency. At 30 kcyc./sec. the T fibre is most sensitive to amplitude increments, and conveys maximal directional information. Both the T fibre and the ear (as judged by the compound potential in the tympanic nerve) respond to steps of 2 dB. The directionality of the ear is enhanced by the contralateral inhibitory connexions of the T fibre. At 15 kcyc./sec. directionality is poor, but is present at 10 kcyc./sec. The T fibre is inhibited by continuous sounds, including the species song. The extent of the inhibitory effect varies with the amplitude of the continuous sound. This may assist in explaining the ‘phasic’ response of the T fibre. There is little habituation to repetitive stimuli. A small interneurone seen in split connectives gives a ‘tonic’ response to song and to continuous sound. It may inhibit the T fibre. Two other auditory fibres are occasionally recorded in the connectives. The T fibre has all the properties required of a warning system responding to pulsed high-frequency sound, and it responds well to bat cries. There is, however, no evidence that it mediates a behavioural response.
Landing Reaction of Musca Domestica: Dependence on Dimensions and Position of the Stimulus
Authors: De Talens A. Fernandez Perez , Ferretti C. Taddei 
Published: April 2021

ABSTRACT
The house-fly exhibits the landing reaction when an expanding optical pattern is placed before it. An expanding pattern which is easy to measure and which keeps the level of illumination constant is created by rotating spirals. In analysing the dependence of landing reaction on the spiral pitch and multiplicity and on the frequency of local stimuli on each ommatidium, (a) interference by the tangential characteristics of the spiral has been observed; (b) stimulus efficiency has been found to depend on stimulus wave-length; (c) the relevance of the above factors and of a temporal parameter influencing both optomotor and landing reactions has been evaluated. The fact that no Moiré effect has been observed is explained in terms of characteristics of stimuli used. The dependence of pattern efficiency on the position of the stimulus in the visual field has been ascertained. Spatial integration of local landing stimuli has been shown in various cases and its threshold excitability and saturation point have been obtained. The dependence of these two last parameters on the position of the stimulus in the visual field has been ascertained.
Further Studies on Synaptic Transmission in Insects
Authors: Pichon Y. , Callec J. J. 
Published: April 2021

ABSTRACT
The dissection of a small length of a giant axon between the 5th and the 6th ganglia of the abdominal nerve cord of the cockroach Periplaneta americana allows extracellular recordings of excitatory post-synaptic potentials (EPSPs) to be made in particularly good conditions. ‘Spontaneous’ or ‘induced’ EPSPs are smaller and slower than those recorded with conventional micro-electrodes. Post-synaptic action potentials are very similar to, or even larger than, those recorded by means of intracellular electrodes. The low impedance of the recording system, together with its stability, allows numerous experiments to be made which were nearly impossible with the microelectrode technique. It is suggested that this technique might be used for other post-synaptic structures.
Water Balance in the Salmon Egg
Authors: Loeffler Clarence A. , Løvtrup Søren 
Published: April 2021

ABSTRACT
The rate of water exchange in the salmon egg was determined by means of the electromagnetic diver-balance. Salmon eggs treated with alcohol to remove the plasma membrane were used to determine the diffusion coefficient, D, for water in the cytoplasm, and untreated eggs to determine the permeability coefficient, E, for water through the plasma membrane. It was found that D is of the same order as that observed in other eggs, whereas the value of E is somewhat lower, but still within the same order of magnitude. The results do not confirm the classical notion that the salmon egg is impermeable to water, but they show that the exchange is extremely slow, the half time being about 24 hr. In order to explain this result the contribution of egg size and environmental temperature must be taken into account. It is concluded that the actually observed rate of swelling corresponds to that anticipated from the recorded permeability coefficient, and that there is therefore no reason to presume that any kind of osmoregulation takes place.
Aerodynamics of Gliding Flight in A Falcon and Other Birds
Authors: Tucker Vance A. , Parrott G. Christian 
Published: April 2021

ABSTRACT
A live laggar falcon (Falco jugger) glided in a wind tunnel at speeds between 6·6 and 15·9 m./sec. The bird had a maximum lift to drag ratio (L/D) of 10 at a speed of 12·5 m./sec. As the falcon increased its air speed at a given glide angle, it reduced its wing span, wing area and lift coefficient. A model aircraft with about the same wingspan as the falcon had a maximum L/D value of 10. Published measurements of the aerodynamic characteristics of gliding birds are summarized by presenting them in a diagram showing air speed, sinking speed and L/D values. Data for a high-performance sailplane are included. The soaring birds had maximum L/D values near 10, or about one quarter that of the sailplane. The birds glided more slowly than the sailplane and had about the same sinking speed. The ‘equivalent parasite area’ method used by aircraft designers to estimate parasite drag was modified for use with gliding birds, and empirical data are presented to provide a means of predicting the gliding performance of a bird in the absence of wind-tunnel tests. The birds in this study had conventional values for parasite drag. Technical errors seem responsible for published claims of unusually low parasite drag values in a vulture. The falcon adjusted its wing span in flight to achieve nearly the maximum possible L/D value over its range of gliding speeds. The maximum terminal speed of the falcon in a vertical dive is estimated to be 100 m./sec.
A Method for Determining Total Carbon Dioxide in Small Volumes of Liquid
Authors: Little Colin , Ruston Gary 
Published: April 2021

ABSTRACT
A microdiffusion method for estimating total dissolved carbon dioxide in volumes of approximately 1·5 μl. is described. The principle of the method is to displace the CO2 with acid, to absorb it in barium hydroxide solution and to measure the change ;n the freezing-point depression of this solution. The range of measurement is 0–30 mm/1. HCO3− with a standard deviation of ± 0·3–0·4 mm/1. In its present form the method cannot be used with smaller volumes without correcting for errors arising from the diffusion of water vapour between the sample and the barium hydroxide solution.
Kinetics of Fertilization in the Sea Urchin: A Comparison of Methods
Authors: Presley R. , Baker P. F. 
Published: April 2021

ABSTRACT
A method is described for the direct counting of male pronuclei in recently fertilized sea-urchin eggs. Using this method, fertilization rate determinations were made to compare 30% artificial sea water (A.S.W.), isotonic KC1, sea water containing lauryl sulphate, calcium-free and magnesium-free A.S.W. containing EDTA, and sea water containing uranyl nitrate, as agents blocking fertilization but permitting further development of previously fertilized eggs. 30% A.S.W. was found to be less satisfactory than the other agents, lacking instant effect, and tending to promote polyspermy. The other agents all gave sigmoid rate curves, that of uranyl nitrate lagging 15– 25 sec. behind the others. Evidence was found that uranyl nitrate acts at a later stage in fertilization than the other agents. Sigmoid rate curves were found, except with 30% A.S.W., when eggs with the bulk of the jelly coat removed, and nicotine-treated eggs, were fertilized. Analysis of sperm distribution among eggs from samples fertilized for more than 40 sec. confirmed that re-fertilization takes place at a lower rate than primary fertilization. The processes blocked by KC1 and uranyl nitrate were found to precede the cortical responses to fertilization, and the termination of nicotine sensitivity.
Wettability and Phylogenetic Development of Feather Structure in Water Birds
Authors: Rijke A. M. 
Published: April 2021

ABSTRACT
The water repellency of feathers is determined mainly, but not exclusively, by a structural parameter which can be expressed in terms of diameter and spacing of the barbs and barbules. Effective waterproofing properties result from the optimal balance of structural parameter and resistance to water penetration. Comparison of the structural parameters for water birds with the geological time interval of their earliest fossil record shows a phylogenetic tendency toward optimizing waterprooftng properties with the course of time. Several behavioural patterns are discussed which may have evolved under the selective pressure of the quality of water repellency and resistance to water penetration.
The Mechanics of Stridulation in Bush Crickets (Tettigonioidea, Orthoptera)
Authors: Bailey W. J. 
Published: April 2021

ABSTRACT
A method has been devised by which the isolated tegmina of bush crickets can be actuated in such a manner as to simulate the insect’s natural song. The actuator was used to make a detailed analysis of the mechanics of sound production, with particular reference to the emission of the more or less pure tone at 15 kHz., characteristic of Homorocoryphus nitidulus. Results involving damping and cautery indicated that the area of the right tegmen responsible for the radiation of this sound was the mirror frame, the vein enclosing the classical mirror membrane. Further experiments involving transduced sound and a probe microphone led to the construction of sound radiation maps of the right tegmen which supported the above view. The cantilever hypothesis, involving the mirror frame with the axis of the vestigial file as the cantilever’s rotational axis, was considered in the light of the Homorocoryphus type. The Homorocoryphus type differed from the Conocephalus type (on which the cantilever hypothesis was based) in that a simpler cantilever is formed in a line direct from the plectrum to the tip of the frame arm.
Sensory Control of Abdomen Posture in Flying Locusts*
Authors: Camhi Jeffrey M. 
Published: April 2021

ABSTRACT
Flying locusts use their abdomens as rudders when executing a variety of flight manoeuvres. In the previous paper (Camhi, 1970) I described the lateral deflexions of the abdomen, which locusts presumably use in yaw correction. The sensory cue evoking this response is a change in the direction of the relative wind, monitored by the cephalic wind receptor hairs. The response appears in tethered locusts only while the wings are flapping in flight, suggesting that the activation of the flight mechanisms closes a neuronal switch, which permits wind-direction information from the cephalic hairs to be processed and translated into an abdominal movement.
Relative Growth, Nucleic Acid Content and Cell Numbers of the Brain in Octopus Vulgaris (Lamarck)
Authors: Packard A. , Albergoni V. 
Published: April 2021

ABSTRACT
The brain of Octopus vulgaris grows allometrically with respect to body weight from 12 mg. at the beginning of post-larval life to 1·95 g. at a body weight of 8·5 kg. The two optic lobes contribute 64% to the wet weight total at the beginning of the growth range and 44% at the end. The 150−fold increase in brain weight is accompanied by a 40−fold increase in total DNA content, 80−85 % °f which is in the optic lobes. DNA concentrations of the order of 20 mg./g. wet weight are found in the vertical lobes. An average of 1 mg. DNA is yielded by 1·9 × 108Octopus sperms and this figure is used to calibrate the nucleic acid content of the optic lobes, and of the suboesophageal and supraoesophageal divisions of the brain in terms of their ‘diploid equivalent’. The ratio between the ‘diploid equivalent’ and the numbers of neurones counted histologically is highest for the suboesophageal division and lowest for the vertical lobes and probably indicates a high glia/neurone index in brain areas with many large cells and low index in those with a homogeneous population of small cells. The brain cells of O. vulgaris do not appear to be polyploid. The RNA/DNA ratio is less than 1·0 in the optic and supraoesophageal lobes, higher than 1·0 in the suboesophageal lobes. The ratio increases during growth, especially in the suboesophageal division.
Salt and Water Balance in Salmon Smolts
Authors: Potts W. T. W. , Foster Margaret A. , Stather J. W. 
Published: April 2021

ABSTRACT
Salmon smolts adapted to sea water maintain a high rate of turnover of both sodium and chloride, but when adapted to fresh water the rate of turnover is low. Only a small part of the influx takes place through the gut. On immediate transfer from sea water to dilute sea water or to fresh water the influxes decline rapidly, but on transfer from fresh water to sea water the restoration of the fluxes takes place slowly. The alternative hypotheses that the rapid changes are due to exchange diffusion or to rapid adjustments of the sodium pump are discussed.
Water Flow Through the Gills of Port Jackson Sharks
Authors: Grigg Gordon C. 
Published: April 2021

ABSTRACT
It has been said that the presence of interbranchial septa in elasmobranchs prevents counter-current flow of water and blood at the respiratory surface. In contesting this opinion, attention is drawn to the importance of the septal canals as ducts carrying respiratory water in the Port Jackson shark. Observations made on the passage of dye through the gills and on water pressures in the orobranchial cavity, septal canals and parabranchial cavity, indicate that water flows unidirectionally between the secondary lamellae and into the septal canals. This provides a counter-current flow between water and blood at the respiratory surfaces.
Use of the First Gill Slits for Water Intake in a Shark
Authors: Grigg Gordon C. 
Published: April 2021

ABSTRACT
The use of the first gill slits as an alternate or accessory route for the intake of respiratory water in the Port Jackson shark is described. This pattern of ventilation is an effective means of oxygenating the blood, but not as effective as normal respiration using the mouth. The use of the first gill slits for water intake is thought to allow respiration to continue during either the crushing of food or obstruction of the mouth while scavenging for food on the bottom. This therefore provides an interesting parallel with the use of the spiracles in skates and rays.
Gas Tensions in Tissues of Trout and Carp Exposed to Diurnal Changes in Oxygen Tension of the Water*
Authors: Garey W. F. , Rahn H. 
Published: April 2021

ABSTRACT
When an artificial gas pocket is formed by injection of air into a tissue space the gases equilibrate with the tissue-blood environment and assume a state of constant composition which is maintained until all the gas is eventually resorbed. In man (Rahn, 1957) and in rats (Van Liew, 1968) evidence has been presented that the O2 and CO2 tensions of gas in such pockets are virtually the same as those of the venous blood draining these tissues provided that air or gases of lower O2 concentrations are breathed (see also review by Piiper, 1965). Since the techniques required for sampling and analysis of the equilibrated gas are relatively simple, this method provides a convenient approach for the determination of gas tensions of the blood-tissue environment of unanaesthetized, unrestrained animals.
Substrate Discrimination in Pectinatella Magnifica Leidy (Bryozoa)
Authors: Hubschman Jerry H. 
Published: April 2021

ABSTRACT
This study is concerned with the role of particle size in habitat selection by the larvae of the colonial bryozoan Pectinatella magnifica Leidy. All experiments were conducted at 25° C. with a 14/10 LD photoperiod. When larvae are provided with a clean glass surface only, they settle and metamorphose with no apparent difficulty. If natural pebbles are provided, the larvae will favour the stone over the glass surface. As the size of substrate particle is reduced, the selective favour is likewise reduced. If larvae encounter only sand-size particles, the preference will return to the glass surface. In experiments in which larvae are offered various other surfaces, settling larvae clearly favoured naturally occurring surfaces over manufactured materials.
Hormonal Control of the Malpighian Tubules of the Stick Insect, Carausius Morosus
Authors: Pilcher Diana E. M. 
Published: April 2021

ABSTRACT
Urine secretion by isolated Malpighian tubules of Carausius is accelerated by a diuretic hormone which can be extracted from the brain, corpora cardiaca and suboesophageal ganglion. The level of this hormone in the haemolymph varies according to the state of hydration of the insect. The hormone is inactivated by the tubules, and a mechanism is proposed whereby the tubules might be controlled by the hormone in vivo.
Chemotactic Turning Behaviour of Tubularia Spermatozoa
Authors: Miller R. L. , Brokaw C. J. 
Published: April 2021

ABSTRACT
Chemotaxis of spermatozoa to female gonophores has been shown to occur in Campanularia, Tubularia and other hydroids (Miller, 1966 a, b). Cinemicrographic records of the movements of Campanularia spermatozoa in the vicinity of female gonophores or of glass capillary pipettes containing extracts of female hydranths have shown that chemotactic aggregation of the spermatozoa occurs because the spermatozoa turn and swim toward the source of chemotactic stimulation (Miller, 1966 a). In the present paper the turning behaviour of hydroid spermatozoa during chemotaxis is examined in greater detail, using multiple-exposure dark-field photomicrography under conditions where the spermatozoa are swimming at an interface between sea water and a glass surface. Under these conditions the changes in bending behaviour of the sperm flagellum can be photographed, in addition to the changes in the path of the spermatozoon. Although this report deals exclusively with spermatozoa of Tubularia, similar results have been obtained from less extensive attempts to photograph the turning behaviour of Campanularia spermatozoa.
Control of Preparatory Feeding Behaviour in the Sea Anemone Tealia Felina
Authors: McFarlane I. D. 
Published: April 2021

ABSTRACT
Dissolved food substances elicit preparatory feeding behaviour in the sea anemone Tealia felina. This behaviour takes the form of expansion of the oral disk and lowering of the margin of the disk. Food may also cause mouth opening and pharynx protrusion. This pre-feeding response may increase the chance of food capture. The expansion and lowering of the oral disk can also be elicited by electrical stimulation of a slow conduction system, the SS1, thought to be located in the ectoderm. SS1 activity is seen when the anemone is exposed to dissolved food substances. It is concluded that preparatory feeding behaviour in Tealia is mediated in part by the SS1.
Osmoregulation of Lampetra Fluviatilis L. and Petromyzon Marinus (Cyclostomata) in Hyperosmotic Solutions
Authors: Pickering Alan D. , Morris R. 
Published: April 2021

ABSTRACT
Freshly caught migrating lampreys were placed in 50% sea water and their method of osmoregulation was analysed. Some osmoregulated more successfully than others. Water balance is maintained by a mechanism involving the drinking of large quantities of water (up to 99·5 ml/kg/day). Sodium, potassium and chloride are absorbed by the intestine (often against a concentration gradient) with the subsequent uptake of water. Divalent ions are not readily absorbed by the intestine and there is some evidence for the secretion of magnesium and sulphate into the gut lumen. The limited urine flow (up to 6·2 ml/kg/day) is used for the excretion of calcium, magnesium and sulphate in high concentrations, but the urine is never hyperosmotic to the blood. The urinary excretion of monovalent ions is not sufficient to eliminate those entering by the intestine and extrarenal excretion at the gills must presumably occur. The breakdown of this osmoregulatory mechanism during the anadromous migration involves: an increase in the permeability of the integument to water, a breakdown of the swallowing mechanism which is not dependent upon the occlusion of the alimentary canal, a reduction in the ability to absorb monovalent ions and water from the ingested 50% sea water, and a loss in the large mitochondria-rich ‘chloride output cells’ of the gills. The similarities between the mechanisms of ‘marine’ osmoregulation of lampreys and teleosts are discussed in terms of the evolution of the two groups, and it is concluded that almost identical osmoregulatory mechanisms have evolved independently.
Oxygen Consumption in Ammocoetes of the Lamprey Ichthyomyzon Hubbsi Raney
Authors: Hill B. J. , Potter I. C. 
Published: April 2021

ABSTRACT
A continuous flow respirometer suitable for measuring oxygen consumption in some small burrowing aquatic animals is described. Rates of oxygen consumption in ammocoetes of the lamprey Ichthyomyzon hubbsi are low, with mean values at 15·5°C ranging from 38·8 to 97·1 μl/g/h for large (3·44 g) and small (0·14 g) animals respectively. A Q10 of 3·6 was found for medium-size animals (1·18g) between 3·5 and 22·5°C. The slope of the logarithmic linear regression relating weight and oxygen consumption was 0·718 at 15·5°C. The rates of oxygen consumption are discussed with respect to the ecology of ammocoetes and compared with those obtained for other lower vertebrates.
Survival and Behaviour of Ammocoetes at Low Oxygen Tensions
Authors: Potter I. C. , Hill B. J. , Gentleman Susan 
Published: April 2021

ABSTRACT
Survival and behaviour studies were made on ammocoetes subjected to water of various tensions of oxygen and carbon dioxide. Ammocoetes can tolerate, for at least 4 days, oxygen tensions as low as 7–10 mmHg at 5°C, 12-16 mmHg at 15·5°C and between 13–16 and 19–21 mmHg at 22·5°C. A limited ability to acclimate to low oxygen tensions was found in some animals. A characteristic emergence behaviour is evoked by low partial pressures of oxygen that approach the lethal level and by high concentrations of carbon dioxide. Ammocoetes respond to low oxygen and high carbon dioxide by an increase in the rate and amplitude of beating of the branchial basket. This increase is maintained in animals able to survive at low oxygen tensions. A high affinity of the blood for oxygen is evident from oxygen equilibrium curves determined on erythrocytes suspension. There was an insignificant Bohr effect at 15·5°C in the pH range 7·68–6·70, although a change occurred in the n value. Haemoglobin concentration, haematocrit and oxygen equilibria suggest that the characteristics of the blood contribute significantly to the ability of ammocoetes to survive in low oxygen conditions.