bluuebunny/crossref_metadata_2025 huggingface dataset:
Proline Inhibition of A Sea Anemone Alarm Pheromone Response
Authors: Howe Nathan R.
Published: April 2021

L-proline, by itself or in animal tissue extracts, inhibits the response of the sea anemone Anthopleura elegantissima to the alarm pheromone, anthopleurine. The effect of proline is mediated by a receptor that is specific for the structure and configuration of the part of the L-proline molecule containing the carboxyl and imino groups. Proline inhibition is competitive, in the sense that the effects of a given proline concentration can be overridden by an increase in anthopleurine concentration. The magnitude of proline inhibition increases with proline concentration and decreases as the duration of exposure to proline increases. Neither the final conducting system mediating the alarm response nor the responding muscles are inhibited by proline. Inhibition presumably occurs at or soon after the level of anthopleurine receptors. Proline inhibition may resolve the potential conflict between Anthopleura’s mutually exclusive feeding and alarm pheromone responses.
A ‘TEA+−Insensitive’ Mutant with Increased Potassium Conductance in Paramecium Aurelia
Authors: Satow Youko , Kung Ching
Published: April 2021

A single-gene mutant of Paramecium aurelia is analysed electrophysiologically. (a) The regenerative Ca-response, triggered by small or moderate current, was smaller and slower in the mutant than in wild type. (b) Input resistance of the mutant membrane is about half of that of wild type bathed in various solutions. This is true for the zero-current input resistance and the chord resistance measured with high depolarizing current, (c) Membrane resistance of the mutant measured with hyperpolarizing currents is smaller than that of wild type only when K+ is the major external cation, (d) Internally applied TEA+ or externally applied Ba+ increases the membrane resistance of the mutant to that of wild type similarly treated. We conclude that the mutant has an increased K conductance.
Spirillum Swimming: Theory and Observations of Propulsion by the Flagellar Bundle
Authors: Winet H. , Keller S. R.
Published: April 2021

The hydrodynamics and energetics of helical swimming by the bacterium Spirillum sp. is analysed using observations from medium speed cine photomicrography and theory. The photographic records show that the swimming organism’s flagellar bundles beat in a helical fashion just as other bacterial flagella do. The data are analysed according to the rotational resistive theory of Chwang & Wu (1971) in a simple-to-use parametric form with the viscous coefficients Cs and Cn calculated according to the method of Lighthill (1975). Results of the analysis show that Spirillum dissipates biochemical energy in performing work against fluid resistance to motion at an average rate of about 6 × 10−8 dyne cm s-1 with some 62−72 % of the power dissipation due to the non-contractile body. These relationships yield a relatively low hydromechanical efficiency which is reflected in swimming speeds much smaller than a representative eukaryote. In addition the Cn/Cs ratio for the body is shown to lie in the range 0·86−1·51 and that for the flagellar bundle in the range 1·46−1·63. The implications of the power calculations for the Berg & Anderson (1973) rotating shaft model are discussed and it is shown that a rotational resistive theory analysis predicts a 5-cross bridge M ring for each flagellum of Spirillum.
Neuronal Basis of A Sensory Analyser, the Acridid Movement Detector System
Authors: Rowell C. H. Fraser , O’shea Michael
Published: April 2021

The Lobular Giant Movement Detector neurone (LGMD) of Schistocerca responds with spikes when small areas of the visual field change in luminance. Previous work has shown that changes of ± 1 log10 unit are enough to produce maximal ON and OFF responses. Using a 5° test area, it is shown that the number of spikes generated by such a stimulus depends on the luminance of the surrounding area. When the surround is dark, the response is maximal; when it is brightly lit, the response is minimal. Intermediate intensities produce intermediate values of response. A × 2 change in response is produced by about 3 log10 units change in surround intensity. A bright annulus, with diameters of 10·5° and 25·8°, inhibits both ON and OFF responses when concentric with the 5° test area, but not when it is 30° eccentric to the test area. The inhibitory effect shows no decrease after 4 min. These results are interpreted to indicate a tonic lateral inhibitory network, sited peripherally in the optic lobe prior to the divergence of the separate ON and OFF channels found in the projection from the medulla to the LGMD. It is probably identical with that described for the lamina by previous workers.
Neuronal mechanisms for object discrimination in the weakly electric fish Eigenmannia virescens
Authors: Feng Albert S. , Bullock Theodore H.
Published: April 2021

The peripheral sensory basis for object discrimination was investigated in the weakly electric fish Eigenmannia virescens. Single unit recordings were made from the primary afferent fibres in the posterior branch of the anterior lateral line nerve while the local electric field (self-generated and simulated) was modified by external resistance and capacitance shunts. Both fibre types (probability and phase coders) responded differentially to capacitance and resistance shunts of equivalent impedance. The degree of response differentiation between the two shunting conditions varied with the intensity of the electrical stimulus at the receptor. These data suggest that the primary electroreceptors can discriminatively encode the two electrical characteristics of ‘objects’. However, since the response of primary electroreceptors also varied with the spatial orientation of the shunting electrodes, central structures must play an important role in object discrimination.
Correlation of the startle reflex and Mauthner cell auditory responses in unrestrained goldfish
Authors: Zottoli Steven J.
Published: April 2021

Stainless-steel electrodes were implanted near the left or right Mauthner cells (M-cells) of goldfish to determine if these cells can initiate the startle reflex evoked by a brief sinusoidal sound stimulus. Recordings of the M-cell extracellular spike were obtained for the duration of 10 experiments. Fish with chronic implants were allowed to free-swim and exposed to at least 10 consecutive sound stimuli consisting of 2 cycles of 200 Hz. Seventy-three startle responses were analysed. In 34 cases the implanted M-cell electrode was contralateral to the contracting musculature, and in each of these cases, a M-cell spike preceded the EMG response by 1· 1−2· 1 ms. In the remaining 39 cases the electrode was ipsilateral to the active musculature, and the M-cell only fired in one of these trials. There were no startle responses and no M-cell firings in an additional 52 tests. Since the M-cell activates contralateral motoneurones, the results indicate it is responsible for initiation of the startle reflex.
Regulation of rectal secretion in saline-water mosquito larvae living in waters of diverse ionic composition*
Authors: Bradley T. J. , Phillips J. E.
Published: April 2021

Larvae of the saline-water mosquito Aedes campestris were adapted to three waters, all having an osmotic concentration of 700 mOsm, but differing in ionic ratios. The (Na + Mg) SO4 medium was much more toxic than the NaHCO3 or the NaCl media. Ionic and osmotic concentrations of haemolymph and rectal secretion were measured in larvae adapted to all three media. The ratio of ionic concentrations in the rectal secretion reflected those in the external medium to which the larvae had been adapted, with the exception of SO42−, which was possibly replaced by HCO3− in the secretion. These differences in rectal fluid composition persisted even though all ligated recta were bathed in the same artificial haemolymph. The Malpighian tubules were found to be the major site of SO42− excretion. In media containing high levels of Na+, Mg2−, K+, Cl− and HCO3−, the rectum secreted a hyperosmotic fluid containing these ions at concentrations several times greater than those found in the haemolymph. These data provide the basis for speculation on the functioning of anal papillae in waters of diverse chemical composition.
The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus*
Authors: Bradley T. J. , Phillips J. E.
Published: April 2021

The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl. Mg−1. h−1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. Haemolymph Na+, Mg2+, K+, Cl−, SO42− and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% sea water and were found to be regulated within a narrow range. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.
The Effect of Calcium on Cadmium Uptake by the Shore Crab Carcinus Maenas
Authors: Wright D. A.
Published: April 2021

The accumulation of cadmium by the shore crab Carcinus maenas (L.) is to some extent dependent upon the calcium concentration of the external medium. This effect is apparently independent of the overall salinity of the external medium and may at least partially explain previous reports of a ‘salinity effect’.

Haemolymph cadmium has a highly significant inverse relationship with the external calcium concentration. This effect is less obvious with other tissues, although the whole body cadmium has a significant inverse correlation with the external calcium concentration. Both the haemolymph and gill show a significant inverse relationship between tissue cadmium and calcium.

When postmoult animals were exposed to 20 μ-mol l− 1 Cd in 100% s.w., high concentrations of both calcium and cadmium appeared in the haemolymph. Postmoult animals in cadmium-free sea water generally had a lower haemolymph calcium concentration than intermoult animals, and the rise in haemolymph calcium seen in the presence of cadmium may indicate some degree of competition for ‘deposition sites’ between these two metals.
Swimbladder Permeability to Oxygen
Authors: Lapennas George N. , Schmidt-Nielsen Knut
Published: April 2021

The permeability of the swimbladder to gas was measured as the conductance to oxygen in seven species of fish. The low over-all conductance resides in the low diffusion constant, K, of the middle layer of the wall (submucosa) while the outer and inner layers (tunica externa and mucosa) have diffusion constants similar to other vertebrate tissues.

The low diffusion constant is due to a low diffusion coefficient, D (not to a low-solubility coefficient), apparently caused by multiple layers of very thin (about 0.02 μm) and broad (up to 100 μm) crystals, clearly identifiable in electron micrographs, and presumably consisting of guanine. Crystals occupy only a small fraction of tissue volume. They are flexible as a consequence of their extreme thinness, and subject to being elaborately folded when the mucosa and submucosa of the secretory part of the swimbladder is contracted during reabsorption of gas. The low conductance of the swimbladder wall reduces the metabolic energy needed to maintain swimbladder volume.
Blood Respiratory Properties of Rainbow Trout (Salmo Gairdneri) Kept in Water Of High CO2 Tension
Authors: Eddy F. B. , Lomholt J. P. , Weber R. E. , Johansen K.
Published: April 2021

1. Blood O2 transport and acid-base balance were studied at 20°C in rainbow trout (Salmo gairdneri) which had been kept in water of high CO2 content (15 mmHg) for at least a week. Also the blood gas chemistry of fish rapidly entering or leaving the hypercapnic environment was studied.

2. Fish entering high CO2 water suffered a sharp decrease in blood pH which significantly reduced O2 transport by the blood, but after a few hours considerable compensation was achieved.

3. After at least a week in high CO2 water, trout showed elevated plasma bicarbonate and PCO2 levels, and a decrease in plasma chloride, while pH was about 0 - 1 pH unit below the level for control fish. Oxygen transport by the blood was marginally reduced.

4. Hypercapnic fish rapidly entering fresh water showed a sharp increase in blood pH and a decrease in blood PO2. These parameters regained normal values after a few hours but plasma bicarbonate and chloride levels took much longer to regain control concentrations.

5. Acid-base balance in hypercapnic fish is discussed with particular reference to the role of the branchial ion exchanges.
Oscillating Contractions in Protoplasmic Strands of Physarum: Simultaneous Tensiometry of Longitudinal and Radial Rhythms, Periodicity Analysis and Temperature Dependence
Authors: Wohlfarth-Bottermann K. E.
Published: April 2021

The construction of a ‘twin-tension transducer’ allows the simultaneous measurement of the same or different contraction rhythms at any selected sites of living plasmodia of Physarum polycephalum. This method has been used to analyse the relation of longitudinal and radial contraction activity within migrating plasmodia and plasmodial veins, under isometric as well as under isotonic conditions of measurement. A periodicity analysis of the oscillating contraction rhythms revealed average period values for the longitudinal contraction cycle of 2·1 min and for the radial contraction cycle of 1·3 min at a temperature of 22 °C. The periods of longitudinal contraction depend on the environment of the strands. The mean value under submerged conditions was 2·9 min. The temperature dependences for both longitudinal and radial contraction cycles were determined to provide reliable values for the normal reaction range of the contractile system (cytoplasmic actomyosin). The values for radial contraction activity are 2·0 min at 16 °C, 1·5 min at 20 °C, and 1·2 min at 24 °C. The range between 16° and 24 °C can be regarded as physiological. The possibility is discussed that only one ‘genuine’ contraction frequency of cytoplasmic actomyosin exists in Physarum.
pH and Haemoglobin Oxygen Affinity in Blood from the Antarctic Cod Dissostichus Mawsoni
Authors: Qvist Jesper , Weber Roy E. , Devries Arthur L. , Zapol Warren M.
Published: April 2021

Blood pH in the antarctic cod (Dissostichus mawsoni) and in two Trematomus species, occurring at –1·9°C, is extremely high ( ∼ 8·2 to 8·3). This supports and extends Rahn’s (1966) model for the temperature-pH relationship in cold-blooded vertebrates.

The blood of D. mawsoni shows a low oxygen affinity (P50 ≃ 14·5 mmHg at pH 8·16 and – 1·9°C). Despite normal in vitro temperature and pH sensitivities, blood P50 increases only slightly when five fish are temperature-stressed ( + 4 ·0 °C), or become acidotic as a result of agitational stress (blood pH 7 ·71 ), primarily as a result of compensatory decreases in blood ATP levels.

Oxygen-binding properties of ‘stripped’ (cofactor-firee) solutions of D. maw-soni haemoglobin were measured in attempts to elucidate the molecular mechanisms involved in the function of the pigment.
Dynamics of Blood Flow Through The Hearts and Arterial Systems of Anuran Amphibia
Authors: Langille B. Lowell , Jones David R.
Published: April 2021

Blood pressures in the ventricle, conus arteriosus, systemic arch and pulmocutaneous arch along with blood flows in the systemic and pulmo cutaneous arches have been recorded in Rana catesbeiana, R. pipiens, R. temporaria and Xenopus laevis. Central pressure and flow waveforms exhibited the same qualitative features in all species. Blood pressure in both the systemic and pulmocutaneous arches passively followed ventricular pressure throughout ventricular ejection. Since diastolic pressure run-off was faster in the pulmocutaneous arch, pressure rose and ejection started in this arch first. The subsequent delay before the onset of ejection and pressure rise in the systemic arch was directly attributable to the time taken for ventricular pressure to rise from pulmocutaneous to systemic levels. Details of arch pressure profiles previously attributed to contraction of the conus, and a consequent occlusion of pulmocutaneous outflow, persisted when conus contraction was eliminated by ligature of the coronary blood supply to the conus for one week. Thus descriptions of a central (cardiac) mechanism for shunting blood to or from the lungs, based on such an active occlusion of pulmocutaneous outflow, are disproven. It is concluded that distribution of blood by the heart to the systemic and pulmocutaneous systems is controlled only by vasomotion in the vascular beds. The cardiac pulse travelled through major arteries with a velocity of 3·1 m/s and thus traversed the complete arterial tree in a very small fraction of a cardiac cycle. Consequently wave transmission phenomena are not important in the arterial systems of Anura. Pressure pulses recorded in peripheral arteries were virtually identical to the central pulse. In addition a simple windkessel model, depicting the arterial tree in terms of a central elastic reservoir supplying peripheral resistance vessels, gave reasonable predictions of arterial pressure-flow relationships.
Variations in the Pattern of Coughing in Rainbow Trout
Authors: Hughes G. M. , Adeney R. J.
Published: April 2021

Recordings of pressure changes within the buccal and opercular cavities of lightly anaesthetized rainbow trout were made simultaneously with movement recordings of the lower jaw and operculum. Coughing movements during the normal rhythm were analysed and in addition coughing cycles evoked by the introduction of dyes into the mouth.

The different patterns recorded could be generally grouped into forward and backward types but a wide range was found. Information regarding the direction of water flow was obtained from analyses of the differential pressure waveforms and this also showed a range in different coughs. It is concluded that many variations of coughing grade into one another and the precise movements producing them and the afferent signals eliciting them remain to be investigated.
Mechanical Organization of Cantilever-Like Sessile Organisms: Sea Anemones
Authors: Koehl M. A. R.
Published: April 2021

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow.

Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0·1 and 0·3 MN.m-2. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile;, A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.
The Effects of Hypoxia and Reoxygenation On Force Development in Myocardia of Carp and Rainbow Trout: Protective Effects of CO2/HCO3-
Authors: Gesser Hans
Published: April 2021

Isometrically mounted and electrically paced myocardial ventricular strips of carp have a much higher capacity to develop force during severe hypoxia and to redevelop force after it than those of rainbow trout.

When the concentrations of CO2 and HCO3− in the solutions surrounding the strips were increased together, such that pH remained constant, the force developed during hypoxia increased. The concentration of CO2 was raised from 0−4%; that of HCO3− from 0−25 IDM. The effect was much more pronounced in the carp strips than in the trout strips.

With the carp strips, the force recovery upon reoxygenation was unaffected by the variations in CO2 and HCO3−. The trout strips, however, recovered better when CO2 and HCO3− had been raised during either hypoxia or reoxygenation.
Clap and Fling Aerodynamics - An Experimental Evaluation
Authors: Bennett Leon
Published: April 2021

The ‘Clap and Fling’ hypothesis, which describes augmentation of lift during the wingbeat of certain insects and birds, was evaluated experimentally in model form. Using induced velocity output as a lift index, and testing at a Reynolds number of roughly 83000, it was learned that:

The main ‘Clap and Fling’ aerodynamic effect consists of raising the lift output realized at the beginning of the stroke. After one chord of travel, ‘Clap and Fling’ effects are minor. Considered over a complete stroke, ‘Clap and Fling’ lift output is limited to 1·15 times the lift output of an identical fixed incidence wing undergoing the same jump start trajectory. ‘Clap and Fling’ output is limited by considerations of maximum circulation and circulation persistence. These limitations are not envisioned in current analyses.
The Action of Juvenile Hormone On the Follicle Cells of Rhodnius Prolixus: The Importance of Volume Changes*
Authors: Abu-Hakima Randa , Davey K. G.
Published: April 2021

The onset of vitellogenesis in Rhodnius prolixus is marked by a reduction in the height of the follicle cells. This decrease is not observed in follicle cells from allatectomized females. Estimates of the changes in cross-sectional area of the cells suggest that the cells shrink to about 50 % of their original volume as the result of JH action. Determination by interference microscopy of the volume of isolated living follicle cells before and after exposure to JH also suggest that the volume is reduced to 50 % of the original volume as a result of JH action. There was no decrease in volume of follicle cells from allatectomized females following exposure to JH. During mid to late vitellogenesis in vivo, an increase in cell volume was measured, an increase that possibly reflects an increase in cellular dry mass. It is concluded that follicle cells normally respond to JH by pumping out fluid, thus reducing their volume, and leading to the development of spaces between the cells.
Effects of Sea Anemones On the Flow Forces They Encounter
Authors: Koehl M. A. R.
Published: April 2021

Two species of sea anemones, Metridium senile and Anthopleura xanthogrammica, illustrate the sorts of compromises made by sessile organisms between maximizing the transport done and minimizing the mechanical forces caused by flow.

M. senile occur in calm areas, but because they are tall, they are exposed to mainstream current velocities. Although A. xanthogrammica occur in areas exposed to wave action, they are short and effectively hidden from mainstream velocities. Measurements of drag forces on anemones and models in a flow tank and in the field indicate that the shapes, sizes, flexibilities, and behaviours of anemones affect the flow forces they encounter. Although M. senile and A. xanthogrammica occur in different flow habitats, the drag force on an individual of either species is about 1 N. The water currents encountered by these anemones and their mechanical responses to the currents can be related to the manner in which the anemones harvest food from flowing water.
On Rate Of Movement in a Flat-Worm as Influenced By Body-Level, Duration of Captivity, and Regeneration
Authors: Robertson J. Armitage
Published: April 2021

(1) Individuals of the common pond flat-worm, Polycelis nigra, were cut into three pieces transversely (heads, mid-pieces, tails), and the speed of their creeping (gliding) movement was tested. (2) It was found that the heads were fastest, the mid-pieces intermediate, and the tails slowest. (3) A gradual process of loss of speed with the continuation of captivity was very noticeable in all pieces. (4) The rate of slowing down (deceleration) was calculated. In one collection this rate was highest in the tails, but in the other it was greatest in the heads. (5) It appears that if pieces be allowed to regenerate without food they can attain a high speed, not only in excess of that previously shown by them when recently cut, but in excess of that of controls kept captive and uninjured for a shorter period. (6) Various control experiments were made on whole worms, with reference to the effects on speed of captivity, size, injury to the anterior end (without decapitation), light-intensity, and anaesthesia. (7) The hypothesis of metabolic gradients and physiological polarity in organisms, due to C. M. Child and his school, has been applied in some of its bearings to the foregoing results. The relative speeds of the three pieces are considered in relation to the evidence of metabolic gradients in respiratory activity, growth, etc., the rates of slowing down are compared in the two collections to the phenomena of direct and indirect susceptibility to poisons, while it is suggested that the recovery of a high speed in regenerated worms is connected with the presence of rejuvenated tissue.

It is hoped that the results may indicate the possible influence of physiological polarity upon the externally manifested, locomotory behaviour, as distinguished from the more fundamental vital activities. There is a tendency to attribute, without more ado, such behaviour of the animal as a whole to the activities of the central nervous system, an attitude which is open to some criticism in an animal of lowly nervous organisation and great regenerative powers.
The Experimental Production of Life Cycles in Ciliates
Authors: H. Darby Hugh
Published: April 2021

Woodruff and other workers claim on the basis of experiment that a single protozoan can be cultured indefinitely without conjugation. Other observers, chiefly centred around Calkins, claim also with experimental support that unless conjugation takes place the protozoa finally die. A review of this controversy and its historical setting is given in Wilson’s The Cell, and nothing is to be gained by its repetition. Less disinterested reviews have been made by Woodruff (1925) and Calkins (1926). Woodruff called attention to the very important fact that, as culture methods have improved, the length of life of the protozoa has been increased. This significant observation is completely omitted by Calkins and the evidence for it will be briefly reviewed here.
The Relative Growth of Parts in Palaemon Carcinus
Authors: Tazelaar M. A.
Published: April 2021

Linear measurements of certain appendages and the carapace of P. carcinus were made and plotted in various ways. The following conclusions were drawn:

The cheliped shows heterogonic growth in both male and female, but more markedly in the male, the values of k being: male 1·8 and female 1·48. The pereiopods in both male and female are slightly heterogonic. The relative growth rates are graded from p3 to p5, that of p3 being slightly greater than that of p5. Of the ordinary pereiopods the rate of growth of p1 is the smallest in the male, but the largest in the female. The difference between the rates of growth of p1 and p3 in male and female is greatest where the rate of growth in the heterogonic organ, the cheliped, is most excessive in the male. The growth of the 3rd maxilliped is slightly negatively heterogonic, the value of k in the male being 0·93 and in the female 0·95.

Hence there seems to be a correlation between the marked heterogony in the cheliped on the growth rate of neighbouring appendages. In those immediately posterior to the cheliped the growth rate is increased and in those anterior decreased.
The Effect of Temperature on the Survival in vitro of Rabbit Spermatozoa Obtained From the Vagina
Authors: Hammond J.
Published: April 2021

The time during which spermatozoa, obtained from the vagina of the female rabbit after service, retain their fertilising power when kept in vitro at diferent temperatures has been determined. At 35° C., or just below body temperature, young are obtained up to 14 hours at 10° C. up to 96 hours and at 0° C. up to 16 hours, there being a well-marked optimum temperature for survival. Not only does the percentage of animals fertile fall with increase in the length of time the semen is kept, but also the average size of the litter decreases in the small litters so obtained the birth weight is increased considerably and the duration of pregnancy slightly lengthened. The percentage of spermatozoa motile, when examined at room temperature is a fairly good indication of the percentage fertility. The sex-ratio is not materially affected by keeping the sperm. Sterility due to adherent tubes was frequent during the course of the experiments. These results with semen obtained from the vagina are compared with those obtained in a parallel series direct from the epididymis of the male under paraffin.
The Effect of Temperature on the Survivalin vitroof Rabbit Spermatozoa Obtained From theVas Deferens
Authors: Walton Arthur
Published: April 2021

A technique is described for the investigation of in vitro problems with spermatozoa removed from the vas deferens of the rabbit. The method involves the protection of the spermatozoa by means of liquid paraffin from evaporation or rapid gaseous exchange. The survival of functional integrity (fertilising capacity) has been shown to be a function of temperature and the effect of temperature has been studied over the range from 45° C. to 0° C. Above body temperature the spermatozoa are rapidly destroyed. At body temperature (40° C.) maximal survival is about 13 hours. As the temperature is lowered survival becomes increasingly prolonged until a maximum of 7 days is reached at 15° C. The curve over the range from 15° C. to 40° C. is only approximately exponential and it is doubtful whether an analogy can be drawn between the effect of temperature on the velocity with which the spermatozoa are destroyed, and the effect of temperature on the velocity of many biological reactions which follow approximately the van’t Hoff and Arrhenius equations. Below the optimum temperature (10°-15° C.) the velocity of destruction is accelerated by fall of temperature. The sex-ratio of the resulting offspring is not significantly altered by keeping the spermatozoa outside the body.
The Relation Between Body Weight and Arterial Cross-Section
Authors: Lyon R. M. Murray
Published: April 2021

The writer has measured the cross-sections of the aorta and of the coronary arteries in a series of animals varying in size from the rat to the horse, for the purpose of determining how variations in body weight influence the cross-sections of these arteries.
The Effect of Polygyny on the Sex Ratio of Mice (Mus Musculus)
Authors: Gates William H.
Published: April 2021

Two series of polygynous matings in mice produced a total of 3430 young, 1803 females and 1627 males, giving a sex ratio of 90.23 : 100 which does not differ significantly from that of the average for the colony, 93.06, indicating that polygyny has no apparent influence on the normal sex ratio, but that high or low ratios are individual characteristics of certain males.
On the Waking-Time of the Nightjar (Caprimulgus E. Europaeus)
Authors: Wynne-Edwards V. C.
Published: April 2021

It has been shown that the waking-time of the song-thrush (Turdus philomelus) and blackbird (T. merula) are accurately regulated by the time of sunrise (1,3), but that in the case of the starling (Sturnus vulgaris) the correlation is not complete (5). Thus if the time of sunrise throughout the year is plotted graphically, it forms a harmonic curve. The daily times of dispersion of starlings from a roost (i.e. from about July to mid-March) also form a harmonic curve, but its amplitude is less than that of the sunrise curve. In August, for example, the birds leave the roost 40–50 minutes after sunrise, and in January 20–25 minutes before, weather conditions being uniform. There is thus a factor which tends to keep the duration of sleep or of activity constant, which acts as a brake on the changing sunrise factor. This second factor appears to be a physiological rhythm.
Temperature and the Responsive Mechanism of Cardiac Muscle
Authors: Brown Dugald E. S.
Published: April 2021

The responsive mechanism by which a muscle cell reacts to a stimulus consists of a group of closely associated processes following each other at definite intervals. Three distinct phases may be recognised in this system: (1) a local process occurring in the region of the stimulus; (2) a rapid series of changes referred to as the propagated disturbance and indicated by the bio-electric variation; (3) the response of the cell in the region adjacent to the seat of stimulation. Associated with each of these phases are various processes which, although separately definable, appear to be integral parts of the whole response. Thus, with the first and second phases are associated chronaxie, the bio-electric variation, the conduction of the propagated disturbance, the absolute and relative refractory periods, and other phenomena. With the third phase, comprising the contraction of the muscle, are associated the latent period of contraction, the duration of the contractile phase, the duration of the relaxation phase, the tension developed, and the heat production. Considerable evidence exists that these are inter-dependent processes and not merely independent concurrent processes (Lillie, 1923; Fulton, 1926). In comparing the velocity of movement of different muscles it has been observed that the more rapid is the movement of the tissue the briefer are chronaxie, the time for the conduction of the propagated disturbance, the time for the development of the bio-electric variation, the duration of the refractory period, the duration of the latent period, and the duration of the isometric contraction. It has been shown also that with the increase of initial tension on the muscle there is associated an increase in chronaxie, in the duration of the isometric twitch, in the total tension, and in the heat production.
Temperature and the Responsive Mechanism of Cardiac Muscle
Authors: Brown Dugald E. S.
Published: April 2021

The rhythmical stimulation of heart muscle, according to the myogenic theory, is of the nature of an auto-stimulation, dependent upon certain processes in the muscle cells themselves. These processes are associated with a system in the cell which undergoes a rapid alteration when a certain critical condition is reached, with a stimulation of the cell resulting. The system then gradually reconstructs itself, undergoing a similar breakdown when the “critical condition” is reached a second time. The time required for the system to pass from the condition existing at stimulation till the critical condition is again attained determines the rate of beat of the heart muscle cell. This unstable system is closely associated with the entire responsive mechanism in the cell and, therefore, is susceptible to modification by the same conditions which are known to modify other phases of the response of the cardiac muscle, such as the duration and magnitude of contraction. The analysis of the exact nature of the relation existing between the rhythmic process and other processes inherent in the system, under conditions known to modify all cellular processes, is essential to any elucidation of the mechanism. The present paper presents the results of an investigation of the action of temperature upon the automatic rate of the sinus and the duration of the simple sinus twitch.
Chorio-Allantoic Grafts of Entire and Fragmented Blastoderms of the Chick
Authors: Murray P. D. F. , Selby Doris
Published: April 2021

The most important work which has yet been done in the experimental embryology of early stages of the chick is that of Hoadley, whose principal contributions are contained in four papers (1926 a, b, c, d). Three of these describe chorio-allantoic grafts of transverse one-fifths of blastoderms at various stages of incubation, while the fourth (1926 d) deals with experiments in which the blastoderm was cut into two pieces while remaining in situ on the yolk, the operation again being performed at several different stages.
Transport of Thallium Ions Across the Isolated Midgut of Hyalophora Cecropia
Authors: Zerahn Karl , Koefoed Bodil
Published: April 2021

T1+ permeates the Hyalophora cecropia midgut equally in both directions, but the flux of Tl+ per mm is up to 50 times higher than the passive flux for potassium, rubidium and caesium. This is explained by assuming that the T1+ flux is a carrier-mediated facilitated diffusion or a passage through channels similar to gramicidin channels in black membranes. We have found this special way for Tl+ to pass through membranes in the Hyalophora cecropia midgut; some other membranes, such as red blood cells, seem to show the same properties, but others, such as frog muscle and skin, do not.
Structure and Function of the Lateral Giant Neurone of the Primitive Crustacean Anaspides Tasmaniae
Authors: Silvey Gerald E. , Wilson Ian S.
Published: April 2021

The syncarid crustacean Anaspides tasmaniae rapidly flexes its free thoracic and abdominal segments in response to tactile stimulation of its body. This response decrements but recovers in slightly more than one hour.

The fast flexion is evoked by single action potentials in the lateral of two large diameter fibres (40 μm) which lie on either side of the cord. The lateral giant fibre is made up of fused axons of 11 neurones, one in each of the last 5 thoracic and 6 abdominal ganglia. The soma of each neurone lies contralateral to the axon. Its neurite crosses that of its counterpart in the commissure and gives out dendrites into the neuropile of each hemi-ganglion.

The lateral giant neurone receives input from the whole body but fires in response only to input from the fourth thoracic segment posteriorly. Both fibres respond with tactile stimulation of only one side. Since neither current nor action potentials spread from one fibre to the other, afferents must synapse with both giant neurones.

The close morphological and physiological similarities of the lateral giant neurone in Anaspides to that in the crayfish (Eucarida) suggest that the lateral giant system arose in the ancestor common to syncarids and eucarids, prior to the Carboniferous.
Thermal Acclimation of A Central Neurone of Helix Aspersa
Authors: Langley C. K.
Published: April 2021

The chemical composition of the haemolymph of adult snails was significantly altered during thermal acclimation (from 19° to 4°, 12° and 30°C), The osmotic concentration was highest in cold groups (4° and 12°C) and lowest in warm-acclimated animals. The concentration of sodium in the haemolymph was highest in warm- and cold-acclimated individuals and lowest at intermediate temperatures (12° and 19°C), and showed significant correlation with [Mg], Potassium concentrations were also increased during warm and cold (4°C) acclimation, the increase being largest in warm-acclimated individuals. The concentrations of calcium and magnesium ions showed relatively small changes during thermal acclimation. Calcium activity was found to be highest in warm and lowest in cold-acclimated snails. Feeding increased the levels of potassium and calcium most significantly in the warm-acclimated group. pH remained relatively constant in all groups.
Thermal Acclimation of A Central Neurone of Helix Aspersa
Authors: Langley C. K.
Published: April 2021

The effects of thermal acclimation on the activity of a central autoactive neurone and its temperature dependence were investigated in Helix aspersa. Resting membrane potential was changed by acclimation temperature, but not with a simple relationship: cells from both 30°C-acclimated and 4°C-acclimated groups were more depolarized at 20°C than were control cells (acclimated to 19°C). The input resistance of the neurone decreased as the temperature of acclimation was raised. Rates of change of potential during an action potential decreased with increasing acclimation temperature. Raising the temperature of measurement on the other hand increased dV/dt at a given acclimation temperature. Spike amplitude was little affected. The frequency of spontaneous spike discharge at a given temperature declined with increasing temperature of acclimation but increased with step changes of temperature in a manner suggestive of a compensatory process. All the measured electrical parameters showed a pronounced hysteresis during rewarming after cold block. Upper lethal and cold block temperatures were both significantly raised by acclimation to higher temperatures. Block temperature was much reduced in cold-acclimated individuals, but the upper lethal temperature was less affected. By sampling during the acclimation period of 4 weeks, the above changes were shown to occur progressively. During the initial stages (5–12 days) they could be partially reversed by incubating isolated ganglia at various temperatures for 30–45 min: but after 2 weeks or more the changes could not be reversed by incubations of up to 5 h.
The Heartbeat of Octopus Vulgaris
Authors: Wells M. J.
Published: April 2021

Heartbeat frequencies and blood pressures were monitored in free-moving Octopus vulgaris. Typical resting frequencies (for animals of 500 g ± at 22° C) were 40–50 beats min−1, with resting pressures measured at the dorsal aorta of 40 cm H2O in systole and 15 cm in diastole, rising to 100 cm or more with a pulse of 50 cm in exercise. Beat frequency changes very little and any increased oxygen demand results mainly in an increase in stroke volume. Temperature affects heartbeat frequency with a Q10 of about 3 over the range 7–27°C. Systemic heartbeat rate and pulse amplitude also change with the oxygen content of the water, slowing as this decreases and stopping, reversibly (at least for short periods), at about 2·5 parts O2 per million.
Evidence That K-Dependent Transport Components in Addition to Na-K ATPase Are Involved in Na and Cl Excretion in Marine Teleost Gills
Authors: Pic P. , Ellory J. C. , Lucu C.
Published: April 2021

Although Tl+ ions can substitute for K+ with a ten-fold higher affinity in activating the sodium pump in mullet red cells and mullet gill microsomal ATPase, they cannot mimic the effects of K+ in stimulating Na+ and Cl− efflux across the gill. This is interpreted in the light of an additional Insensitive transport component being involved.
Blood Acid-Base Balance in Brook Trout (Salvelinus Fontinalis)*
Authors: Packer Randall K. , Sunkin Arthur L.
Published: April 2021

A nomogram is presented which allows the rapid assessment of acid-base status in brook trout (Salvelinus fontinalis Mitchill) at 18°C.

Due to a of 3·5–4·3 mmHg in the respirometer water, the fish from which data were obtained for determination of zero base excess values were suffering from slight respiratory acidosis. Trauma of surgery and anaesthetization as well as confinement in the respirometer might also have generated a slight metabolic acidosis.

Base excess values for trout with a chronically implanted dorsal aortic cannula ranged from −3 to + 3m-equiv/l. Blood buffer values of d[HCO3−]/dpH = 7·50±4·42 slykes and were found. Mean plasma protein concentration was 3·6± 0·8 g/100 ml plasma and the buffering power of plasma was approximately 40% that of whole blood. Plasma proteins are more important blood buffers in fish than in humans.
Acid-Base Balance and Gas Exchange in Brook Trout (Salvelinus Fontinalis) Exposed to Acidic Environments
Authors: Packer Randall K.
Published: April 2021

Brook trout (Salvelinus fontinalis Mitchill) with a chronically implanted dorsal aortic cannula were exposed to acidic environments. During exposure, trout developed severe metabolic acidosis as shown by decreases in standard plasma bicarbonate levels as well as negative base excess values. Reduced oxygen consumption seen in acidotic trout resulted from decreased gill oxygen transfer and reduced available blood oxygen capacity.
Bilateral Effects On Retinal Shielding Pigments During Monocular Photic Stimulation in the Crayfish, Procambarus
Authors: Barrera-Mera Baltazar , Berdeja-García G. Yolanda
Published: April 2021

Bilateral light adaptation of distal retinal shielding pigments was observed a few minutes after 60 min of sustained photic stimulation (2·69 Cd/m2) of a single eyestalk of the dark-adapted crayfish. Pigment migration was observed in intact animals as a diminution of eye glow area and electroretinogram amplitude, and was confirmed in sectioned material. The effect upon the contralateral eye was abolished by surgical bisection of the cerebral ganglion. It is suggested that the mechanism involved in the bilateral effect may be responsible for the mutual entrainment of ERG circadian rhythms of both eyes.
Potentiation of Neuromuscular Transmission by An Octopaminergic Neurone in the Locust
Authors: O’Shea Michael , Evans Peter D.
Published: April 2021

Spikes in the octopaminergic dorsal unpaired median (DUM) neurone which innervates the extensor tibiae muscle of the locust metathoracic leg (DUMETi) produce direct and indirect effects on muscle tension. Direct effects include a slowing of an intrinsic rhythm of contraction and relaxation, a relaxation of muscle tone and a small hyperpolarization of the muscle membrane potential. The latter two effects are weak and variable. All three effects are mimicked by superfusion of octopamine and are mediated by octopamine receptors on the muscle fibres. Indirect effects are found when the DUMETi neurone is stimulated at the same time as the motoneurones innervating the extensor muscle. They include (a) potentiation of tension generated in the extensor muscle by spikes in the slow excitatory motoneurone (SETi), (b) reduction in duration of each twitch contraction generated by SETi due to an increase in the rate at which the muscle relaxes, (c) increase in the amplitude of the synaptic potential generated by SETi. These various effects have a time course of several minutes and far outlast the duration of DUMETi stimulation. They can be mimicked by superfusion of octopamine. The effect of DUMETi on neuromuscular transmission is mediated by receptors with a high affinity for octopamine located both on the muscle and on the terminals of the slow motoneurone. The presence of the presynaptic receptors is revealed by the increase in the frequency of spontaneous miniature end plate potentials recorded in the muscle in the presence of octopamine. DUMETi is a member of a group of similar aminergic neurones and it is suggested that they may share a role in modulating transmission at peripheral neuromuscular synapses, and possibly central synapses.