bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dances of Honeybees at Small Zenith Distances of the Sun
Authors: New D. A. T. , New J. K. 
Published: April 2021

ABSTRACT
The dances of honeybees have been studied in Jamaica (18° 00′ N.), Trinidad (io° 38’ N.), and British Guiana (5° 11′ N.) when the sun was near the zenith. When the zenith distance of the sun was less than about io° the orientation of the observed dances deviated, often very widely, from the direction expected if the bees were indicating the angle between the sun azimuth and the food-source azimuth. But the dance angles did not show the wide scattering to be expected from a failure of perception of sun azimuth. They were frequently well orientated, and successive dances often progressively changed direction clockwise or anticlockwise. The dance angles plotted against time gave smooth curves symmetrical about noon, but of smaller maximum slope than the curves of changing sun azimuth. The direction of turning of the dances was often opposite to that expected from the direction of sun azimuth change. Various conceivable explanations are discussed. It is concluded that the dances can best be explained as the result of two control mechanisms : (i) A mechanism which uses all available information about the real sun azimuth and limits the possible dance angles to a certain range. This range becomes increasingly wide the nearer the sun approaches to the zenith. (ii) A mechanism which takes into account the dance directions (or sun positions) memorized for particular times of day, and between successive memorized positions turns the dances through an angle proportional to time. This mechanism is subject to the limits imposed by mechanism (i). This dual-control hypothesis would provide a general explanation of the orientation of honeybee dances. It could explain the orientation of dances at night and when the sky is completely covered with cloud. Evidence is presented that the acuity with which bees can perceive the position of the sun relative to the zenith is not less accurate than 2°–3°. This is a measure of the accuracy with which they can localize a visual stimulus relative to the direction of gravity. The mechanism proposed for orientating the dances would provide a possible means whereby bees might communicate the direction of a food-source by dances which do not indicate the angle between the azimuths of the food-source and the sun.
The Dynamics of Burrowing of Some Common Littoral Bivalves
Authors: Trueman E. R. , Brand A. R. , Davis P. 
Published: April 2021

ABSTRACT
The process of burrowing in the Bivalvia has been studied in a restricted range of species only, notably in members of the Solenacea (Fraenkel, 1927), the Lucinacea (Allen, 1958), and the Veneracea (Quayle, 1949; Ansell, 1962). This previous work, summarized by Morton (1964), makes little reference to burrowing in the common British littoral species and, with the exception of Ansell’s paper, lacks the precision which more modern techniques of recording may give. The object of this research was to study the process of burrowing in detail in Tellina tenuis, Macoma balthica, Donax vittatus and Cardium edule, common littoral bivalves with very different shell shapes and habits.
The Swimming Performance of the Sea-Anemone Boloceroides*
Authors: Josephson Robert K. , March Steven C. 
Published: April 2021

ABSTRACT
Boloceroides can swim orally by repeated aboral-oral flexions of its tentacles which make up over 90% of the weight of the anemone. Tentacles at different distances from the mouth beat slightly out of phase, with more marginal tentacles leading more oral ones. Isolated tentacles occasionally give aboral-oral flexions like those of attached tentacles during swimming. Early in a bout of swimming the stroke frequency is about 1·2 strokes/sec. and the swimming velocity about 1·9 cm./sec. The stroke frequency is slightly higher in small animals than in large ones. The swimming velocity achieved is independent of animal size. In tethered swimming the maximum forward force developed during a stroke increases with animal size approximately as the square of the diameter of the tentacle crown. About 80 % of the forward impulse produced during the effective portion of the stroke cycle is negated by rearward impulse during the recovery portion of the cycle. The average forward force for the whole cycle is only about 5 % of the maximum force.
Studies of the Cleavage in the Frog Egg
Authors: Kubota Tomoyuki 
Published: April 2021

ABSTRACT
The time scale of nuclear division with reference to cleavage time was prepared for the normal egg of Rana nigromaculata. Two experimental procedures, (a) removal and (b) screening of the mitotic apparatus, were performed in the eggs at various times before the beginning of the first cleavage, in order to determine when the furrowing activity of the cortex became independent of the mitotic apparatus. The two experiments concordantly indicated that an autonomous capacity for furrowing was established in the cortex between the metaphase and the late anaphase. Notwithstanding its extremely large size, this critical stage for the frog egg is practically the same as those which have been reported in other smaller cells.
The Physiology of Excretion in the Cotton Stainer, Dysdercus Fasciatus, Signoret
Authors: Berridge M. J. 
Published: April 2021

ABSTRACT
The preparation of isolated Malpighian tubules is described. The rate of urine flow increases with increasing serum dilution, and vice versa. Urine is almost isotonic with haemolymph over a wide range of osmotic pressure. Serum collected from 3-day-old insects promotes urine formation, whereas that from 6-day-old insects does not. A factor which was extracted from the m.n.c. accelerates the rate of urine flow, from a normal value of 0·87 to 3·1 nun.3 × 10−3 /min. The osmotic pressure of the urine, however, remains unchanged. The hormone concentration of different parts of the nervous system was assayed with these isolated tubules. Most activity occurs in the m.n.c., but some activity is present in extracts from the c.c. and the fused ganglionic mass in the mesothorax. Malpighian tubules isolated from 6-day-old insects remain inactive, but after the addition of hormone they immediately begin to produce urine. These observations have been incorporated into a tentative hypothesis on the control of excretion in Dysdercus.
Flight in Drosophila
Authors: Vogel Steven 
Published: April 2021

ABSTRACT
Apparatus has been devised to record the principal parameters of the flight performance of tethered fruit-flies in a wind tunnel. Typically these flies achieve level flight (lift = weight) at 200 cm./sec. and a body angle of + 10°. Lift varies directly with body angle except at very high angles; the stroke parameters are invariant with body angle. Evidence is presented suggesting that these measurements are applicable to free flight. The adaptive significance of the absence of a ‘lift-control’reaction’ in fruit-flies is discussed.
Kinetics and Route of Active K-Transport in the Isolated Midgut of Hyalophora Cecropia
Authors: Harvey W. R. , Zerahn K. 
Published: April 2021

ABSTRACT
The time lag for attaining a steady state of 42K movement from blood-side to lumen was 2-4 min. The flux of was changed as much as 100-fold with but minor effects on the lag time. The specific activity of the gut did not approach 100% of the blood-side value in this short time although the specific activity of K arriving in the lumen from the transport mechanism must be 100%. From these results we conclude : I that the K being transported through the gut cannot be mixing with the total cell K of the gut, and therefore II that the route of K transport may be through just the goblet cells, or III that the K may pass through special pathways between or through epithelial cells.
Locust Wind Receptors
Authors: Camhi Jeffrey M. 
Published: April 2021

ABSTRACT
Tethered locusts begin opening their wings about 45 msec, following wind stimulation of the facial setae. Tethered locusts also begin wing opening at least 30 msec, after release of tarsal contact with the substratum. High-speed ciné photography reveals that an untethered locust in a take-off jump initiates wing opening as early as 15 msec, after the first detectable jumping motion. Therefore in free jumps neither stimulation of the facial setae by the jump wind nor release of tarsal contact is the factor inducing wing opening. The actual mechanism acts much more rapidly, and probably involves central, rather than peripheral, coding. During flight, the extent of forewing pronation on the downstroke is a function of the wind speed over the facial setae, higher speeds resulting in decreased pronation. With increasing wind speed no change in pronation appears until about 80 msec., after which the effect is exaggerated for several hundred milliseconds, finally trailing off slightly to the maintained level. The data suggest that the ‘wind-indicator’ interneurones of the cervical connective are active in the lift-control reflex. A suggested behavioural function of this reflex is rapid ascent following the acceleration produced by a take-off jump.
The Responses of Nephtys (Polychaeta: Annelida) to Changes in Hydrostatic Pressure
Authors: Morgan Elfed 
Published: April 2021

ABSTRACT
An increase in pressure elicited swimming in Nephtys, the number of worms induced to swim being related to the amplitude of the pressure change within the range of stimuli investigated. A decrease in pressure inhibited swimming. The latency of the response to both an increase and a decrease also appears to be related to the magnitude of the stimulus, the worms responding more rapidly to the bigger pressure changes. Brief pulses of pressure lasting 1 sec. elicited neither increase nor decrease in the level of swimming, but pulses of 5 sec. duration induced some individuals to swim. Releasing the pressure at the end of the 5 sec. period resulted in a decrease in the swimming activity below the pre-stimulus level. It is suggested that the different responses may be mediated via separate receptor mechanisms. Phase-angle analysis of the responses to cyclical changes in pressure suggested that the worms were responding primarily to the rate of change of pressure, but the response did not appear to be a simple sine-function of the stimulus. The worms also seemed to be responding in part to some component occurring at twice the basic cycle.
The Renal Excretion of Nitrogenous Compounds by the Duck (Anas Platyrhynchos) Maintained on Freshwater and on Hypertonic Saline*
Authors: Stewart D. J. , Holmes W. N. , Fletcher G. 
Published: April 2021

ABSTRACT
The excretory rates of total nitrogen, uric acid, urea and ammonia by intact birds maintained on fresh water did not differ significantly from the corresponding rates of excretion by birds maintained on saline equivalent to 60 % sea water (284 mM-NaCl, 6·0 mM-KCl). The uric acid excreted by these birds contributed 53·8%, the ammonia 29·2% and the urea 1·5% of the total nitrogen excreted. The three compounds together accounted for 84·5 % of the nitrogen excreted. The glomerular filtration rates (inulin clearance) and the renal plasma flow rates (PAH clearance) did not differ between the freshwater-maintained and the saline-maintained birds. The clearance of uric acid in all groups of birds was equal to the PAH clearance and may be interpreted as a reliable measure of the renal plasma flow rate. The urea:inulin clearance ratios for the individual urine samples from all birds suggested that renal tubular synthesis and secretion of urea may occur. In a second set of experiments uric acid and urea concentrations in the plasma of fed ducks were followed during adaptation to hypertonic saline and during a similar period of dehydration. A sharp in the increase plasma uric acid concentration was generally observed in all groups of birds after feeding and the concentration then gradually declined to the prefeeding level. The plasma urea concentrations of birds given saline equivalent to 60% sea water equilibrated, after the first 24 hr., at about twice the concentration found in the freshwater-maintained birds. In birds maintained on saline equivalent to 100% sea water (470 mM-NaCl; 10 mM-KCl), the plasma urea concentration steadily rose during the first 50 hours and then equilibrated at a level approximately 10 times that observed in freshwater-maintained birds. Withholding all drinking water from birds which had been previously given fresh water resulted in a rise in the plasma urea concentration during the first 50 hr. similar to that observed in the birds maintained on saline equivalent to 100% sea water. But the plasma urea concentration of these birds, in contrast to that of saline-maintained birds, continued to rise throughout the remainder of the experimental period.
Functional Anatomy and Movement Co-Ordination of the Respiratory Pump of the Carp (Cyprinus Carpio L.)
Authors: Ballintijn C. M. 
Published: April 2021

ABSTRACT
An anatomical description of the head skeleton of the carp (Cyprinus carpió) is given. The description is limited to what is relevant for the functioning of the respiratory pumps. An anatomical description of the head muscles of the carp is given. The result of the contraction of most of the head muscles through coupling of skeletal elements spreads farther over the respiratory system than only to the bones to which the muscles are attached directly. It is through this that in the first place all the muscles producing laterad movements, with the exception only of the dilator operculi, influence the volume of both the buccal and opercular cavities, and in the second place that contraction of the hypobranchial muscles not only results in vertical movements of the floor of all the respiratory cavities, but also in laterad movements of their side walls. The hyoid arch plays a central role in the coupling system because it interconnects almost all the other elements. The functional significance of the interaction through couplings is integration of the respiratory movements through which during low-intensity breathing whole muscles can cease to be active and during high-intensity respiration whole muscles can be recruited without seriously affecting the co-ordination of the movements and hence the hydrodynamic efficiency of the pumps.
Interaction of the Movements of the Two Eyecups in the Crab Carcinus
Authors: Barnes W. J. P. , Horridge G. A. 
Published: April 2021

ABSTRACT
The movements of the two eyecups of the crab, Carcinus, have been recorded simultaneously during optokinetic responses. Experiments in which the eyes view different visual stimuli reveal that, at the start of a response, the eyecups have a considerable degree of independence and can even move in opposite directions. As the response progresses, interaction between the eyes increases, until the eyecups move at similar velocities in the direction of the slower of the two visual inputs, or are stationary. Similar interactions between the eyes were observed during memory responses and during the responses to sinusoidal oscillation of the two sets of stripes. Each eye has its own system for converting perceived motion into eyecup movement. These two systems are linked on the afferent rather than the efferent side of the brain. The fast phase of optokinetic nystagmus is governed by the eye whose fast-phase movement occurs away from the midline, and the fast phases of this eyecup lead the other by 30-80 msec. Also, fast phases only occur at their normal frequency when the governing eye can see the stripes.
Two-Dimensional Records Of The Eyecup Movements Of The Crab Carcinus
Authors: Barnes W. J. P. , Horridge G. A. 
Published: April 2021

ABSTRACT
The eyecup movements of the common shore crab, Carcinus maenas L., have been recorded in two dimensions. Saccades and eyecup drift occur in all directions. Eyecup tremor is a complex irregular movement although horizontal tremor predominates in most crabs. Although the response to the movement of the light in a circle is usually an approximate circle or ellipse, rectangular responses are occasionally obtained and the eyecup often moves in a stepwise fashion in response to a smooth diagonal movement of the light. The angle of response to a diagonal movement depends on the ratio of the response to horizontal and vertical movements alone. The eye is virtually stabilized in all planes by a contrasting object but never fixates upon a moving stimulus. No torsional or twisting movements of the eyecups were obtained in response to light stimuli.
The Ionic Basis of Axonal Conduction in the Central Nervous System of Anodonta Cygnea (Mollusca: Eulamellibranchia)
Authors: Treherne J. E. , Mellon DeForest , Carlson Albert D. 
Published: April 2021

ABSTRACT
The compound action potentials recorded in cerebro-visceral connectives consisted of a large homogeneous slow component, with a conduction velocity of between 0·03 and 0·04 m.sec−1, together with a variable rapidly conducting component, showing spikes with maximum velocities in the region of 0·4–0·5 m.sec-1. Comparison of the square of the conduction velocity, for the various components of the compound action potential, with distribution of axon diameters in the connective showed that the small axons (0·1–0·3µ in diameter) contributed to the slow component, the larger axons (2·0–6·0 µ in diameter) forming the initial rapidly conducting spikes. The small axons showed a rapid loss of function in preparations bathed in isotonic sucrose solutions. The larger axons, however, continued to function for appreciable periods in isotonic solutions of non-electrolytes. The larger axons were rapidly and reversibly blocked by dilute tetrodotoxin. Additional evidence is also presented which suggests that the action potentials associated with the axons are sodium-dependent and do not depend upon any appreciable involvement of calcium ions in carrying the action current. Both the large and the small axons appear to be relatively accessible to small ions and molecules in the bathing medium. The results are discussed in relation to the possible physiological mechanisms involved in the function of the larger axons in sodium-free solutions.
Exchanges of Sodium Ions in the Central Nervous System of Anodonta Cygnea
Authors: Mellon De Forest , Treherne J. E. 
Published: April 2021

ABSTRACT
The concentrations of sodium and potassium ions have been measured in the blood and tissues of the cerebro-visceral connective of the freshwater mussel Anodonta. It is shown that, despite the relatively low concentration of sodium ions in the blood, a concentration gradient of this cation is maintained between the extracellular fluid and the nerve cells because of the extremely low intracellular concentration of this cation. Experiments using 24Na and 22Na have shown that there is relatively rapid exchange of sodium ions between the blood and the central nervous tissues. The efflux of labelled sodium occurred as a two-stage process, in which an initial fast fraction gives way to a slower exponential decline. The results can be accounted for on the assumption that efflux of sodium ions in the fast fraction, at o° C., represents the cations contained in the extracellular fluid. This assumption implies that there is little regulation of the over-all concentration of sodium ions in the extracellular fluid. The results are discussed in relation to the available evidence on the structure and electrophysiology of the cerebro-visceral connectives.
The Ionic Basis of the Fast Action Potentials in the Isolated Cerebro-visceral Connective of Anodonta Cygnea
Authors: Carlson Albert D. , Treherne J. E. 
Published: April 2021

ABSTRACT
The large axons in the cerebro-visceral connective have been shown to function for appreciable periods in preparations bathed in sodium-free non-electrolyte solutions. The results of experiments on the effects of organic monovalent cations and anions, together with observations on the effects of tetrodotoxin, procaine and manganous ions and the changes in conduction velocity in tris chloride and dextran solutions indicate that the action potentials are, nevertheless, mediated by conventional sodium-dependent mechanisms. Radioisotope experiments show that there is a small fraction, of approx. 0.5 mM/kg. tissue, which does not exchange rapidly with the 22Na in the bathing medium and which can be depleted by stimulation in sodium-free solutions. On the basis of these observations it is suggested that there is sequestered extra-axonal sodium fraction which can be utilized by the large axons to maintain action potentials in preparations bathed in sodium-free solutions.
Effects of High Hydrostatic Pressures on the Activity and Behaviour of the Ciliate Spirostomum
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
Spirostomum ambiguum fails to make the avoiding reaction at pressures of 4000 p.s.i. and over. The critical pressure is between 2000 and 4000 p.s.i. Light or moderate mechanical stimulation with a hair no longer produced reversal or body contraction at pressures over 4000 p.s.i. Blows severe enough to kink the body surface, or sudden exposure to NaCl in solution, elicited prolonged reversal at 6000 and 7000 p.s.i. In a direct current the cilia on the cathodal side reversed with a threshold voltage either the same or not more than twice as great as that required without application of pressure. It is suggested that at pressures of 4000 p.s.i. and over the cilia at the anterior end of the organism fail to receive and translate the stimulus. This failure could be due either to the reduced activity of the cilia or perhaps to an impairment of mechanical properties of the ectoplasm.
Irradiation of Sperm Tails by Laser Microbeam*
Authors: Goldstein Stuart F. 
Published: April 2021

ABSTRACT
Sea-urchin and starfish sperm tails were irradiated at pre-selected points along the flagellum and at pre-selected phases of the beat cycle by means of a pulsed ruby laser microbeam. Multiple-exposure dark-field photomicrographs were taken immediately before and after irradiation. The flagellum usually appeared to be broken at the irradiated point. The portion of a flagellum between the head and the irradiated point continued for at least a few beats if its length was at least 25% of the length of the tail, and stopped immediately if it was shorter. Bends already established beyond the irradiated point continued to propagate to the tip of the flagellum. Their propagation velocity generally decreased, and there were usually changes in other bend parameters. No new bends ever developed beyond the irradiated point. Irradiation within a bent region often completely eliminated that region.
Some Requirements for Mating in the Rabbit Flea, Spilopsyllus Cuniculi (Dale)
Authors: Mead-Briggs A. R. , Vaughan J. A. 
Published: April 2021

ABSTRACT
Rabbit fleas Spilopsyllus cuniculi (Dale) do not mate while on adult rabbits; copulation is usually initiated when the fleas are on the body of a new-born rabbit and at least the close proximity of such a nestling is essential. The female probably becomes receptive only after close contact, but not necessarily probing contact, with a young nestling. Fleas with mature ovaries mate much more readily than immature fleas. Male fleas must be in a suitable ‘physiological state’ before they can mate and inseminate females. This state is reached by probing contact with rabbits in the final stages of pregnancy or, for a relatively shorter period, with new-born rabbits. Spermatozoa of such fleas show much greater mobility within the genital ducts than those from fleas kept on male or non-pregnant rabbits.