bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Movement of Gas in the Respiratory System of the Duck
Authors: Bretz W. L. , Schmidt-Nielsen Knut 
Published: April 2021

ABSTRACT
A single inhalation of marker gas (argon) was administered to unanaesthetized ducks. Pargon was continuously monitored in the interclavicular, cranial thoracic, caudal thoracic and abdominal air sacs with a mass spectrometer during the marked inspiration and subsequent respiratory cycles. The sequence of arrival times of the inspired marker at the various sampling sites was determined; ventilation rates of the different air sacs were compared by examining the rate of decrease of Par during washout of each sac. The experimental results agree with previously proposed patterns of air flow in the duck respiratory system. It is proposed that the movement of gas in the respiratory system of birds is a two-cycle event. During the inspiratory phase of the first cycle, inhaled air is drawn into the posterior air sacs ; during the expiratory phase of the first cycle, this air (having mixed with the residual air in the posterior air sacs) is pumped into the secondary and tertiary bronchi of the lung; during the inspiratory phase of the second cycle this air in the lung passage-ways is drawn into the anterior air sacs; and finally, during the expiratory phase of the second cycle, this air is exhaled from the anterior air sacs and the respiratory system.
Electrophysiological Studies on the Heart of the Bivalve Mollusc,Modiolus Demissus
Authors: Wilkens Lon A. 
Published: April 2021

ABSTRACTElectrical activity from the heart of Modiolus demissus was recorded simultaneously by sucrose-gap and microelectrode techniques, confirming the validity of the extracellular method of assessing the shape of the action potential. Hearts beat in Na-free SW (Tris) but with loss of the plateau and a reduced rise time. Mechanical contractions did not persist, however, for more than 2 h in the absence of sodium, and the viability of the preparation declined rapidly after 3 h. Lithium substitution (for sodium) also failed to support the plateau and tetro- dotoxin had little effect on the spike. Hearts also beat in Ca-free SW. Here, the spike component and contractile activity were lost at nearly the same time although slowly rising plateau-like potentials persisted for over 6 h. EGTA potentiated the effects of Ca-free SW, and manganese had calcium-anta-gonizing effects producing longer plateaus. Spikes and plateau phases could be selectively initiated from hearts made quiescent in Na-free and Ca-free SW by readmitting either ion individually. In Na-free SW spike amplitude and rate of rise were increased by raising calcium concentration. This effect was self-limiting at high levels of calcium, however, and the spike was reduced. In divalent-free solutions (Ca- and Mg-free SW) the membrane was depolarized to near zero potential. In this situation the membrane permeability to sodium exceeded that to potassium, and the membrane behaved as a sodium electrode. It is concluded that the action potential in Modiolus heart is dependent primarily on calcium for the spike component and on sodium for the amplitude of the plateau. Calcium is also important in the control of plateau duration and membrane permeability by reason of its stabilizing properties. A possible correlation exists between the occurrence of the plateau, calcium sensitivity and habitat of three bivalve species. The hearts of Modiolus and of the oyster have plateaus and will beat in Ca-free SW, and these bivalves live in estuarine habitats, whereas Mytilus lives in a subtidal environment and its heart is sensitive to low calcium and has no plateau component.
An Analysis of a Circadian Rhythm of Oviposition in Oncopeltus Fasciatus
Authors: Rankin Mary Ann , Caldwell Roy L. , Dingle Hugh 
Published: April 2021

ABSTRACT
Oviposition in Oncopeltus fasciatus shows a daily periodicity, eggs being laid 4–10 h after light onset. In constant light the inter-ovipositional interval is temperature dependent, being about 12 h at 28 °C and 27 h at 23 °C. Ovariectomized females began to display normal ovipositional behaviour and attempt oviposition after hypertrophy of the fat body. Ovariectomized females attempt to oviposit 4–10 h after light onset, just as do normal intact females, indicating that control of the time of oviposition lies, at least in part, outside the ovary.
The Mechanism of Blood Circulation inAnodonta Anatina(L.) (Bivalvia, Unionidae)
Authors: Brand A. R. 
Published: April 2021

ABSTRACTThe structure of the blood circulatory system of Anodonta anatina is described and the haemodynamics have been investigated by recording pressures in the ventricle, auricle, pericardial cavity and pedal haemocoele at rest and during burrowing. Ventricular systolic pressure is usually 2 − 4 cm in the resting animal; during burrowing it increases to between 6 and 10 cm and this is sufficient to maintain the blood supply to the foot for most of the digging cycle. Auricular and pericardial cavity pressures fall rapidly (by about 1·0 cm) during ventricular systole, confirming the operation of a volume-compensating mechanism for refilling the heart. High peaks of pressure at spontaneous phasic adduction and during the adduction and retraction movements of the digging cycle are generated equally throughout all parts of the animal enclosed within the shell and do not create large gradients of pressure in the haemocoele; the longer duration of these pressure peaks in the pedal haemocoele produces small transient gradients of pressure which could result in the movement of blood out of the pedal haemocoele. At spontaneous phasic adduction contraction of the pedal muscles may assist the flow of blood from the pedal haemocoele. There is some evidence that Keber’s valve limits blood flow from the pedal haemocoele during active burrowing. Although body movements may assist the movement of blood through parts of the peripheral circulation, they do not generate a high venous return pressure. The form of the circulatory system effectively isolates the heart from pressure changes in the pedal haemocoele.
The Median Inferior Frontal Lobe and Touch Learning in the Octopus
Authors: Wells M. J. , Young J. Z. 
Published: April 2021

ABSTRACTAfter removal of the median inferior frontal lobe, blinded octopuses already trained to discriminate by touch between rough and smooth spheres continued to do so, but at a lower level of accuracy. Animals without pre-training showed a strong tendency to take rough objects after this operation and learned to discriminate well only when trained to take rough and reject smooth. When animals with intact inferior frontal lobes were given food in the presence of a smooth sphere they learned to take the smooth; in subsequent extinction tests they continued to take the smooth but soon ceased to take rough objects. Animals without median inferior frontal lobes also increased their tendency to take a smooth object associated with food. But they did not behave in the same way as controls in extinction tests; they continued to take the rough objects even if they had not been rewarded for doing so. Operated animals thoroughly pre-trained to take smooth objects showed some capacity to discriminate these from rough objects in subsequent successive training with food and shock, though continuing to take the rough far more than control animals. Animals without brain damage could be taught to take smooth rather than rough objects on one side, and continued to do so when trained in the reverse direction on the other. There was, however, some lateral interference; performance on the unreversed side was worse after the introduction of reversed training. Animals with lesions to the median inferior frontal lobe failed to learn on the reversal (rough+/smooth−) side, responses to both objects declining progressively as training continued. At the same time as this discrimination by the non-reversal (smooth+/rough−) side continued to develop. There was thus no evidence of lateral transfer in these animals. It was confirmed that tactile learning is still possible after removal of the vertical and basal lobes, but with some decrease in the normal preference for smooth objects. The median inferior frontal is thus not essential for tactile learning, but greatly facilitates it, making some contribution to the acquisition of both positive and negative responses, perhaps by spreading information through both sides of the touch-learning system. The effect of its removal in touch learning can be compared with the effect of vertical lobe removal on visual learning. It is concluded that one function of these parts is to compensate for the intensity of stimulation so that animals do not pay undue attention to brightly reflective or texturally rough objects.
Auditory Discrimination between Compressions and Rarefactions by Goldfish
Authors: Piddington R. W. 
Published: April 2021

ABSTRACTGoldfish were taught to discriminate between a given click and the same click inverted, that is, with the compression and rarefaction phases reversed. The responses were true auditory responses involving the sacculus but not the lateral line. The responses were independent of both waveform (frequency) and intensity and could be elicited with single clicks. Phase was the relevant parameter. Tail flips were found to send a rarefaction wave (rarefaction is the first deflexion) forward from the fish and a compression wave backward. It is proposed that phase analysis of tail-flip sounds is used to tell whether a swimming fish is approaching or receding.
The Swimming of Nymphon Gracile (Pycnogonida)
Authors: Morgan Elfed 
Published: April 2021

ABSTRACT
During the swimming of intact Nymphon gracile the legs beat ventrally in a metachronal sequence starting from the rear, and with a phase delay of approximately one-third between successive appendages. The first and fourth ipsilateral legs thus beat together, usually in synchrony with either the second or the third contralateral leg, rather than halfway between them. The pattern of leg movement in swimming involves a succession of such combinations, e.g. (R4 R1 L2) (R3 L4 L1) (R2 L3), and the preferred gait alternates between this sequence and its mirror-image combination. Amputation of one or both of the third leg pair was followed by a lateral movement of the adjacent legs, but the rhythm of movement was little impaired, to the extent of reducing slightly the phase delay of leg 2 in leg 4 on the same side. The effect of an imposed cycle of movement on the phase relationship of adjacent legs suggests that proprioceptive feedback plays only a little part in entraining the rhythm, but there is some evidence for reflex coupling between adjacent legs. This appears to be strongest within the segment. The results are best explained in terms of negative coupling between oscillators controlling each leg.
Sodium Efflux from the Central Nervous Connectives of the Cockroach
Authors: Tucker Lois E. , Pichon Y. 
Published: April 2021

ABSTRACT
It has been found that the efflux of sodium from intact penultimate connectives of the ventral nerve cord of the cockroach, Periplaneta americana, can be represented by three components with half times of approximately 30 sec, 100 sec and 16 min. The rate at which sodium escapes in the fast component is correlated with the height of the extraneuronal potential developed when a connective is exposed to a high-potassium bathing medium, the slower the rate of sodium escape the larger being the size of the extraneuronal potential. This gives support to the hypothesis that the extraneuronal potential is a diffusion potential brought about by restriction to ion movement imposed by the tight junctions at the inner ends of the perineurial clefts. De-sheathing a connective greatly speeds up the rate of sodium efflux, the fast component being the most affected. These results can be explained in terms of a three-compartment system, the properties of which are affected by stretching and de-sheathing. It is concluded that the movement of ions is regulated at different levels of the C.N.S. but that the peripheral barrier (which is responsible for the production of the extraneuronal potential) may be the most important one in non-steady-state conditions.
A Note on the Biliary System of the Domestic Duck and a Method for Collecting Bile
Authors: Crompton D. W. T. , Nesheim M. C. 
Published: April 2021

ABSTRACT
The morphology of the biliary system of the domestic duck is described. There is a connexion between the hepato-enteric and cysto-hepatic ducts. Consequently, the bile secreted in the right and left lobes of the liver need not drain separately into the duodenum via the cysto-enteric and hepato-enteric ducts respectively. A simple apparatus and method for collecting bile from ducks is described. The method could easily be modified for other animals which possess a gall-bladder.
Ionic Distribution in Amoeba Proteus
Authors: Prusch Robert D. , Dunham Philip B. 
Published: April 2021

ABSTRACT
The intracellular concentrations of K, Na, Ca and Cl in Amoeba proteus are 24·83, 1·08, 2·93 and 9·73 mM/kg cells respectively. Intracellular Na is always slightly higher than that of the external medium when external Ca is low. Addition of Ca to the medium reduces the intracellular concentration of Na by decreasing the permeability of the plasmalemma to Na. The membrane potential of Amoeba proteus in Prescott-James medium is −89·5 mV and is sensitive to changes in both external K and external Na when external Ca is low. Intracellular Na and K are both sensitive to the addition of CN to the external medium. Both Na and K are actively transported in the amoeba ; K is actively accumulated from the external medium and Na is actively expelled from the cell. It has been suggested that the effects of Ca on Amoeba proteus, i.e. reduction of PNa, reduced internal concentration of Na, reduced unidirectional Na and K influxes, and increased membrane resistance are due to Ca binding to the plasmalemma.
Structure and Synaptic Activation of the Fast Coxal Depressor Motoneurone of the Cockroach, Periplaneta Americana
Authors: Iles J. F. 
Published: April 2021

ABSTRACT
Using Procion Yellow dye injection the structure of the fast coxal depressor motoneurone was determined. The cell body of the slow depressor motoneurone was located within the metathoracic ganglion. Intracellular records from the fast motoneurone failed to reveal any post-synaptic response when the largest abdominal giant fibres were stimulated. Smaller abdominal afferent fibres gave an excitatory input.
Aspects of Osmotic and Ionic Regulation in the Sturgeon
Authors: Potts W. T. W. , Rudy P. P. 
Published: April 2021

ABSTRACT
Analyses have been made of the blood and urine of the euryhaline sturgeon Acipenser medirostris and the rates of turnover of sodium and water in both sea water and fresh water have been measured. The blood concentration is rather lower in fresh water than in sea water and the concentration of magnesium ions declines markedly. The rate of turnover of sodium ions is high in sea water and similar to that of marine teleosts. The rate of turnover of sodium is much lower in fresh water but adaptation to fresh water is slow and the animals are more permeable to sodium than are teleosts. The rate of turnover of tritiated water is more rapid in fresh water than in sea water but in each medium it is similar to that of teleosts of a similar size.
Operant Conditioning As A Means of Testing the Ability of White-Crowned Sparrows to Discriminate Star Patterns
Authors: Terhune Elinor C. 
Published: April 2021

ABSTRACT
Operant conditioning can be a valuable technique for investigating biological problems, as has been demonstrated with pigeons (e.g. Meyer, 1964; McDonald, 1968). If an appropriate operant is selected, such as perch-hopping, the technique can be extended to passerine birds. Stevenson (1967) used alighting on a perch as the conditioned response with first-year male chaffinches which lived in the experimental chamber. Bastian & Hothersall (1970) obtained high fixed-ratio responses (FR up to 40) with redwinged blackbirds, which again lived in the experimental cages.
Limited Permeability and Metabolism of L-Glutamate in the Locust Gut Wall
Authors: Murdock L. L. , Koidl B. 
Published: April 2021

ABSTRACT
A method is described which enables the passage of nutrients through the gut wall of locusts to be studied quantitatively in vivo. The method consists of infusing the radio-labelled precursor into the gut lumen while the haemocoel is perfused with saline. The perfusate is collected and analysed. Compared to L-alanine and glycine, intact L-glutamate crosses the locust gut wall slowly, if at all. Metabolism of L-glutamate in the gut wall is extensive, that of alanine markedly less, while there is little metabolism of glycine. It is suggested that limited permeability and extensive metabolism in the gut wall combined to severely restrict the entry of intact dietary L-glutamate into the blood. The gut wall may be an important site of regulation of blood L-glutamate, preventing or hindering influx of this abundant dietary amino acid. The system could be a contributing factor in protecting neuromuscular synapses from non-adaptive excitation by helping to prevent the concentration of blood L-glutamate from rising.
Blood Metabolites After Intestinal Absorption of Amino Acids in Locusts
Authors: Murdock L. L. , Koidl B. 
Published: April 2021

ABSTRACT
After infusion of the locust gut with L-glutamate-U-14C, L-glutamine was found to be the major radioactive product in blood sampled 1 h later. Smaller amounts of alanine were also found. In most experiments not even traces of unchanged L-glutamate were detectable. When D-glutamate was infused, the main radioactive product was D-glutamate, with lesser amounts of glutamine. With L-alanine-1-14C, the major product was unchanged alanine, with smaller amounts of glutamine. With glycine-1-14C, only glycine could be recovered. Gastric caeca, which presumably are the major tissue sites of amino acid absorption, metabolized L-glutamate to glutamine and alanine. Metabolism of glycine was-negligible. Slow infusion of L-glutamate-1-14C into the haemocoel of locusts was followed by recovery of the radioactivity from blood as glutamine. Unchanged L-glutamate was not in evidence. Rises in the blood concentration of L-glutamate appear to be suppressed. This seems not to be the case for D-glutamate, L-alanine, and glycine. Destruction of dietary L-glutamate in the gut wall may be a functional adaptation to help maintain a low blood concentration of the pharmacologically active substance while producing energy required for absorption and tissue maintenance. Should any L-glutamate enter the blood from the gut or other tissue source, it will be converted to glutamine, which suggests the existence of a complementary mechanism for ensuring low blood L-glutamate.
Water Exchange in the Mantle of A Terrestrial Snail During Periods of Reduced Evaporative Loss
Authors: Machin J. 
Published: April 2021

ABSTRACT
Based on surface temperature, steady-state rates of evaporation of the mantle of inactive Otala lactea are very low even down to 1·5 % relative humidity. Mantle permeability is 0·016 mg/cm2/h per mmHg vapour pressure difference. Marked peaks in surface temperature following humidity change are interpreted as net gain or loss of water to the mantle. Smaller fluctuations in surface temperature are interpreted as limited mucusgland activity. The existence of a superficial hygroscopic layer overlying an impermeable barrier in the mantle is discussed.
Electrotonic Coupling Between Identified Large Cells in the Buccal Ganglia of Planorbis Corneus
Authors: Berry Michael S. 
Published: April 2021

ABSTRACT
The electrotonic coupling between three pairs of large neurones in the buccal ganglia is compared.
In both ganglia a large motoneurone (cell 3) is coupled to a smaller, ipsilateral neurone (cell 4) which is probably a motoneurone also. Neither cell is coupled to its symmetric partner. The coupling is quite strong when measured by the transmission of long, intracellularly applied pulses but spikes are considerably attenuated. Resultant EPSPs are of short duration and usually ineffective. Cell 4 produces bursts of spikes but cell 3 is silent unless artificially depolarized close to threshold when it produces a burst of spikes simultaneous with the cell 4 burst; individual spikes are not synchronous. Cell 2, whose function is unknown but which is not involved in feeding, is cross coupled to its symmetric partner. The coupling is strong, and a spike in one cell produces a large electrotonic EPSP, which often reaches threshold, in the other. One cell may drive the other or they may fire simultaneously owing to synchronous pacemaker depolarizations. Short periods of reverberation occur. All observed input was excitatory and chemically mediated. Following nerve stimulation the input is of similar large amplitude (up to 30 mV) in each cell and the resulting spikes are synchronous. The cells are therefore co-ordinated both by common input and direct connexions.
Ciliary Activity and the Origin of Metachrony in Paramecium: Effects of Increased Viscosity
Authors: Machemer Hans 
Published: April 2021

ABSTRACT
In forward-swimming Paramecium the direction of metachronal wave propagation is turned progressively clockwise from forward-right to backward-left if the viscosity of the medium is increased to more than 100 cP. With increasing viscosity the direction of the power stroke is turned clockwise at a lower rate than the direction of waves. This leads to a gradual transformation of the dexioplectic metachrony toward a symplectic pattern. As viscosity is raised the polarization of the ciliary cycle in time and space is progressively reduced, so that the beat becomes increasingly helicoidal. Metachronal coordination gradually breaks down at viscosities of more than about 100 cP, but is retained better at the anterior end of the cell than in more posterior regions. At viscosities above 12 cP the left-handed swimming helix of Paramecium is changed into a right-handed helix. This is produced primarily by the viscositydependent clockwise shift in the direction of the power stroke from backward-right to backward-left. The frequency of peristomal cilia (32/s. at 20 °C) decreases with rising viscosity. Under constant conditions, a posteriorly directed gradient of decreasing frequency can be observed with the stroboscope. Raising the viscosity leads to an increase of the average wavelength from 10·7 µm at 1 cP to 14·3 µm at 40 cP. In the same range of viscosity the wave velocity, which is the product of frequency and wavelength, is reduced from 340 to 200 µm/s, since the drop in frequency exceeds the increase in wavelength. The wave velocity tends to be stabilized by reciprocal relations between frequency and wavelength, if all other factors are kept constant. However, the wavelength is found to be different in forward-swimming and backward-swimming animals at 40 cP without a change in frequency (14·1 bps; 14·3 compared to 12·7µm). This is explained if the metachronal wavelength is increased by decreasing polarization of the ciliary cycle. A working hypothesis is put forward which explains the origin of a metachronal system by the distribution of forces parallel to the cell surface produced by polarized or unpolarized cycles of ciliary movement.
Mechanical Tuning of the Acoustic Receptor of Prodenia Eridania (Cramer) (Noctuidae)
Authors: Adams William B. 
Published: April 2021

ABSTRACT
Mechanical stimulation of the tympanic membrane with vibrating probes eliminates the acoustic tuning of the receptor and allows the mechanical tuning to be determined. Using neural firing rates as a measure of the response magnitude, three separate regions of high sensitivity are found. They are centred at approximately 2, 14 and 60 kHz. Displacements of 0·1 to 1·0 Å suffice for excitation at 60 kHz. The regions of high sensitivity appear to correspond to the first, third and fifth order mechanical resonances of the scoloparium. Comparison with the results of acoustic stimulation experiments indicates that low-frequency acoustic stimuli are filtered out by the acoustic system of the receptor.