bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
(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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACTA 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 Effect of Polygyny on the Sex Ratio of Mice (Mus Musculus)
Authors: Gates William H. 
Published: April 2021

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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.