bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Substance P and Vasoactive Intestinal Polypeptide on Gastrointestinal Blood Flow in the Atlantic Cod Gadus Morhua
Authors: Jensen Jörgen , Axelsson Michael , Holmgren Susanne
Published: April 2021

The cardiovascular effects of vasoactive intestinal polypeptide (VIP) and substance P (SP) in vivo were studied in the Atlantic cod Gadus morhua. Special interest was focused on the distribution of blood to the gastrointestinal circulation.

VIP increased the blood flow to the gut by increasing cardiac output and by decreasing resistance in the vascular bed supplied by the coeliac artery. In addition, VIP had an inhibitory effect on spontaneous stomach motility.

SP induced a triphasic response in the coeliac artery blood flow. An initial increase was followed by a rapid decrease, to the control level or below, and a second increase in flow. The triphasic response was not changed after vagotomy, while atropine blocked the second phase, the decrease, indicating that a local cholinergic mechanism is involved. The significance of this temporary decrease in flow remains to be elucidated. SP also caused an increase in cardiac output and in mesenteric artery blood flow. In addition to the increase in cardiac output, the increase in gastrointestinal blood flow produced by SP is accomplished by a decreased resistance in the coeliac and mesenteric vascular beds.
Ontogeny of Heart Function in the Little SkateRaja Erinacea
Authors: Pelster Bernd , Bemis William E.
Published: April 2021

The development of the cardiovascular system has been analysed in embryos of the little skate, Raja erinacea, ranging in age from 27 to 144 days after spawning. Circulation starts at the end of the first month. At that time, the heart is S-shaped, there is no differentiation between ventricle and conus arteriosus and no valve formation is detectable. Complete differentiation of the central circulatory system and its valves was observed at about 40 days after spawning, although there are changes in proportion that occur before hatching.

In the smallest embryos used for physiological studies, 27 days post-spawning (0.01–0.03g body mass), circulation of blood was observed and heart rate was 35–40 beats min−1. Heart rate increased with development, reaching a maximum of 65–68 beats min−1 at a body mass of 0.2 g (60 days post-spawning) and then slowly decreased until just prior to hatching.

Ventricular diastolic pressure remained below 0.1 kPa throughout development whereas ventricular systolic pressure increased significantly with increasing body mass. In small embryos (<0.05 g) the conus arteriosus collapsed at the end of each heart beat, completely occluding its lumen and separating the ventral aorta from the diastolic heart. In larger animals (>0.1g) serial flap valves in the conus separated the ventral aorta from the diastolic ventricle, and the conus supported ventral arterial blood pressure because of its elastic properties.
Effect of Pregnancy and Temperature on Red Cell Oxygen-Affinity in the Viviparous Snake Thamnophis Elegans
Authors: Ingermann Rolf L. , Berner Nancy J. , Ragsdale Frances R.
Published: April 2021

The oxygen affinity of red cell suspensions from fetal garter snakes was higher than that of cell suspensions from their mothers. This difference appeared to be due to different concentrations of nucleoside triphosphate (NTP, primarily adenosine triphosphate). NTP concentrations were significantly higher, and oxygen affinities were significantly lower, in red cell suspensions from pregnant females compared with those from nonpregnant females or males; there is no precedent for such a pronounced effect of pregnancy on the oxygen affinity of maternal blood. These data indicate that pregnancy may result in an enhanced ability of adult blood to deliver oxygen to the fetus. Since the binding of organic phosphates and oxygen to hemoglobin is sensitive to temperature, and since these animals experience diurnal changes in temperature, we examined the influence of relatively low (20°C) and high (34 °C) temperatures on red cell oxy gen-affinity. The temperature increase of 14 °C resulted in a lowered oxygen-affinity of all red cell suspensions examined. However, this increase in temperature lowered the affinity of maternal red cells to a greater extent than it did the affinity of fetal red cells. This suggests that daytime temperatures may further enhance the ability of maternal blood to deliver oxygen to the fetus at times when fetal oxygen demand is probably greatest.
Transintestinal Acetate Transport in a herbivorous Teleost: Anion Exchange at the Basolateral Membrane
Authors: Titus E. , Ahearn G. A.
Published: April 2021

Purified basolateral membrane vesicles were prepared from the intestinal epithelium of the tilapia Oreochromis mossambicus, a herbivorous teleost. Characteristics of volatile fatty acid (VFA) transport were investigated using [3H]acetate as a representative anion. No significant change in [3H]acetate influx was observed in the presence of a cation gradient (K+ or Na+) compared to the influx observed in the absence of a cation gradient, indicating the lack of cation-dependent coupling for acetate transport. The time course of [3H]acetate uptake into vesicles preloaded with acetate or bicarbonate was enhanced compared to [3H]acetate uptake into vesicles preloaded with gluconate. A series of transstimulation and cis-inhibition studies involving both organic and inorganic anions indicated the presence of a highly specific anion-exchange carrier which readily exchanged [3H]acetate with the volatile fatty acids (formate, acetate, propionate and butyrate) and bicarbonate. Kinetic analysis of [3H]acetate influx as a function of external acetate concentration yielded a biphasic uptake curve which was interpreted as carrier-mediated transfer (Jmax=21,77±2.05 nmol mg−1 protein 10s−1; Km=12.70±2.95mmoll−1) plus apparent diffusion (P=0.17±0.02 nmol mg−1 protein 10s−1 mmol−1 acetate). [3H]Acetate uptake was also a hyperbolic function of internal bicarbonate concentration, displaying a relatively low HCO3−half-saturation constant (Km=0.41 mmol l−1). Intact intestinal sheets mounted in Ussing chambers demonstrated net absorptive fluxes of [3H]acetate when serosal acetate concentration was maintained at 1.0 mmol l−1 and the mucosal acetate concentration was varied from 1.32 to 10.0mmoll−1. At mucosal acetate concentrations lower than 1.32 mmol l−1, a net secretion of VFAs was observed. Transepithelial transport of [3H]acetate was significantly inhibited by the presence of acetazolamide. A transintestinal transport model for volatile fatty acids is proposed in which specific anion antiporters, located on the brush-border and basolateral poles of the cell, exchange luminal VFAs for serosal and intracellular bicarbonate, resulting in net transepithelial uptake of VFAs. This process is driven by a downhill lumen-to-blood VFA concentration gradient and the intracellular generation of bicarbonate by carbonic anhydrase.
Skeletal Muscle Deformation in the Lateral Muscle of the Intact Rainbow TroutOncorhynchus MykissDuring Fast Start Maneuvers
Authors: Covell James W. , Smith Michael , Harper David G. , Blake Robert W.
Published: April 2021

Although there is an extensive body of information on the kinematics of the fast start response in teleosts, there is little information on the deformation of the skeletal muscle which produces the changes in body position during a fast start. This study presents preliminary information on the determination of skeletal muscle deformation with implanted ultrasonic dimension gauges in the intact fish during startle behavior. Deformation was measured in the lateral epaxial musculature of the rainbow trout Oncorhynchus mykiss during stage one of fast starts. The results show that ultrasound transit time dimension gauges can be implanted in the skeletal muscle of rainbow trout with minimum trauma and used to record local deformation along the length of the fish. Measurements remained stable over 4–8 h of implantation. Preliminary results show that: (1) muscle at different positions along the fish reaches its minimum length (average 9.6% shortening) at approximately the same time and coincident with the end of stage one of the fast start response; (2) the onset of concave curvature of the entire fish precedes the onset of local shortening at more caudal sites; (3) muscle on the convex side of a bend lengthens while muscle on the concave side shortens, and the two deformations follow a similar time course. These results indicate an asynchronous onset of skeletal muscle contraction in fast starts and support the hypothesis that local skeletal muscle deformation is transmitted caudally through skeletal or other structures.
Perturbation of the Motor System in Freely Walking Cockroaches: II. The Timing of Motor Activity in Leg Muscles After Amputation of A Middle Leg
Authors: Delcomyn Fred
Published: April 2021

The effects of amputation of a middle leg on the motor pattern in the legs of freely walking cockroaches (Periplaneta americana L.) were studied. The general effects of amputating a middle leg are similar to those arising from amputation of a rear leg. These effects are: multiple bursting, more variable and inconsistent timing (phase) between bursts and a tendency for timing effects to appear only during relatively slow walking. The phase of bursts in the amputated stump relative to bursts in the leg in front of it was speed-dependent. However, the phase of stump bursts relative to bursts in the legs across from and behind the stump were not especially dependent on the speed of walking. In general, the phases of bursts in most leg pairs seemed relatively little affected by the amputation except for an increase in scatter. It is concluded that loss of a middle leg disrupts the motor pattern less severely than does loss of a rear leg. The implications of this and other results for the understanding of motor control are discussed.
FMRFamide-LIKE IMMUNOREACTIVITY IN THE CRAYFISH NERVOUS SYSTEM
Authors: Mercier A. Joffre , Orchard Ian , Tebrugge Victoria
Published: April 2021

FMRFamide-like immunoreactivity (FLI) was detected in the nervous system of the crayfish Procambarus clarkii using an antiserum that recognizes extended RFamide peptides. Immunocytochemistry revealed FLI in neuronal somata, axons and varicose processes within the central nervous system. In the periphery, plexuses of immunoreactive varicosities were present in the pericardial organs (POs), in thoracic roots and on the hindgut. The hindgut plexus arose from 3–5 axons leaving the sixth abdominal ganglion (A6) via the intestinal nerve. The presence of FLI in these locations was confirmed by radioimmunoassay. In contrast, no FLI was detected in motor axons innervating exoskeletal muscles of the abdomen.

The POs contained by far the largest amount of FLI of all tissues examined. The immunoreactive material was partially characterized by extraction and separation on two consecutive reversed-phase high performance liquid chromatography (RP-HPLC) columns. The largest amount of immunoreactivity on the second column co-eluted with a synthetic peptide, SDRNFLRFamide (F2), previously identified as one of two or more FMRFamide-related peptides contained in lobster POs. The immunoreactive fractions and peptide F2 elicited similar effects on isolated crayfish hearts; all increased the rate and amplitude of spontaneous cardiac contractions. As with the immunoreactivity, the highest level of bioactivity was contained in the fraction that co-eluted with F2.

The results suggest that FMRFamide-related peptides act as neurohormones in crayfish and are likely to play roles in controlling circulation and defecation.
5-Hydroxytryptamine: A Second Diuretic Hormone in Rhodnius Prolixus
Authors: Maddrell S. H. P. , Herman W. S. , Mooney R. L. , Overton J. A.
Published: April 2021

Bioassays of 5-hydroxytryptamine (5-HT) in fifth-instar Rhodnius prolixus haemolymph using Calliphora salivary glands indicate that: (1) biologically active 5-HT is present, (2) in unfed animals there is not enough 5-HT to stimulate Malpighian tubule fluid secretion, and (3) there is enough 5-HT soon after the initiation of feeding to stimulate rapid tubule secretion. The 5-HT receptor antagonists ketanserin and spiperone reversibly and selectively inhibit 5-HT-induced fluid secretion, indicating the presence of specific 5-HT receptors on Rhodnius Malpighian tubules. The data provide evidence that 5-HT is a naturally occurring hormone acting with a previously described peptide hormone to regulate diuresis in this species.
Peptide Potentiation of Calcium Channel Activity can be Seasonally Variable
Authors: Bishop C. A. , Krouse M. E. , Wine J. J.
Published: April 2021

Using the single-channel patch-clamp technique we have recently shown that the peptide cotransmitter proctolin can potentiate the activity of a large (38 pS in 137 mmol l−1 Ba2+; 26 pS in 137 mmol l−1 Ca2+), depolarization-inducible Ca2+ channel in the plasma membrane of the crayfish tonic flexor muscle (Bishop et al. 1991). Parallels between the modulatory effects of the peptide on channel activity and tension generated in the muscle suggest that this channel activation is probably partly responsible for the amplification of tension by proctolin (Bishop et al. 1991). Our initial studies of this phenomenon were performed during the spring and summer of 1988, using excised, inside-out patches. During that time, we found that the addition of 5×10−9moll−1 proctolin to the bath at least 5 min prior to seal formation (this dose gives a maximal response) caused a large increase in the proportion of patches with active channels and enhanced the single-channel open probability, Po by as much as 40-fold. (Ca2+ channels remained remarkably active in these excised patches: there was usually no obvious diminution in channel activity for the duration of the recordings; Bishop et al. 1991.) Identical results were obtained during the spring of 1989. In this communication we show that, during the winter months between these two periods, proctolin had virtually no effect on channel activity, indicating a seasonal variability in the potentiating effect of the peptide.
Neural Regulation of Pupariation in Tsetse Larvae
Authors: Žďárek Jan , Denlinger David L.
Published: April 2021

A neural mechanism coordinates pupariation behavior and tanning in the tsetse larva. At parturition, the mature larva has already received sufficient ecdysteroid to commit the epidermal cells to metamorphosis but, before sclerotization and tanning of the cuticle can begin, the larva must first select a pupariation site and then proceed through a stereotypic sequence of pupariation behavior that culminates in the formation of a smooth, ovoid puparium. Both pupariation behavior and tanning are inhibited by the central nervous system (CNS) during the wandering phase. This central inhibition is maintained by sensory input originating in the extreme posterior region of the body. At the transition from wandering to pupariation, the posterior signal that induces inhibition of pupariation behavior is removed and the larva begins the contractions associated with pupariation, but the CNS inhibition of tanning persists. At this point, separation of the body into two halves by ligation or nerve transection prevents tanning of the anterior half (containing the CNS), whereas the denervated integument of the posterior half tans completely. Transection of nerves to the midline of the body produces larvae with a tanning pattern that ends abruptly along a sagittal plane, implying that the central control of this process is uncoupled between the left and right regions of the CNS. A few minutes later, when the final shape of the puparium is completed, the CNS inhibition is lifted and the tanning process begins. At this time, separation of the body into two halves by ligation or nerve transection has no inhibitory effects on either part. Exogenous ecdysteroids fail to release the CNS inhibition, and hemolymph containing the pupariation factors from Sarcophaga bullata have no accelerating effects on tsetse pupariation. These results imply that regulation of metamorphosis in the insect integument is not the exclusive domain of blood-borne hormones.
Reversal of Interleg Coupling in Backward Locomotion Implies a Prime Role of the Direction of Locomotion
Authors: Eilam David , Shefer Gabi
Published: April 2021

Conventional descriptions of interleg coupling relate to anatomical definitions such as fore- or hindlegs, right or left legs (i.e. the body is the frame of reference). This convention is obvious for forward walking, where forelegs (in anatomical terms) are also the leading legs (in terms of direction). In backward locomotion, however, the leading legs in terms of direction are the hindlegs in terms of anatomy. What effects do the anatomy and direction of movement have on the sequence of stepping? Our observations on the locomotion of mole rats in a transparent acrylic tunnel revealed that, as in nature, mole rats moved both forwards and backwards. They typically employed a diagonal sequence of steps in forward walking, whereas in backward walking they typically employed a lateral sequence. However, when stepping was described with movement direction as the frame of reference, both forward and backward walking were made up of the same sequence of steps. The same invariant trend was recorded during backward galloping, but to a lesser extent than during walking. We suggest that the backward sequence is simply a reversal of the forward sequence: a hindleg during backward locomotion acts like a foreleg in forward locomotion, while a foreleg acts like a hindleg in forward locomotion. Interleg coupling therefore remains invariant in relation to the direction of locomotion.
The Fatty Acid 8,11,14-Eicosatrienoic acid Induces Spawning in the Male Lugworm Arenicola Marina
Authors: Pacey A. A. , Bentley M. G.
Published: April 2021

Spawning of the lugworm Arenicola marina (L.) (Annelida: Polychaeta) occurs in both sexes following the release of a sex-specific maturation hormone from the prostomium. In males this has been termed sperm maturation factor (SMF). Chromatographic purification of SMF, using an in vitro bioassay, has led to it being putatively identified as the 20-carbon fatty acid 8,11,14-eicosatrienoic acid and this paper describes the induction of spawning in vivo by injection of 8,11,14-eicosatrienoic acid into sexually mature individuals.

It is shown that spawning in male A. marina occurs following the injection of prostomial homogenate or 8,11,14-eicosatrienoic acid into the coelomic cavity of sexually mature specimens. The injection of 8,11,14-eicosatrienoic acid into the coelomic cavity of females does not cause spawning although it can be induced by a hormone present in the prostomium. There are, therefore, clear sex-specific differences in the chemical signal that causes spawning in this species. Sex-specific differences in the behaviour of spawning animals are also described.

The study identifies a role for the fatty acid 8,11,14-eicosatrienoic acid in the spawning of male A. marina. This is the first description of a hormone in the annelids, for which both the chemical structure and the endocrine role are known.
Apneic Oxygen Uptake in the Torpid Bat, Eptesicus Fuscus
Authors: Szewczak Joseph M. , Jackson Donald C.
Published: April 2021

Like many mammalian heterotherms, the big brown bat, Eptesicus fuscus, breathes intermittently during torpor. By exploiting this bat’s preference to roost in crevices, we could separately measure O2 uptake during ventilatory bouts and apneic periods using a flow-through metabolic chamber with a small dead space volume and short time constant. Oxygen uptake was measured during apneas ranging from 10 to 150 min duration at body temperatures of 20, 10 and 5 °C. The fraction of total O2 uptake acquired during apnea was 0.26±0.03 (9), 0.54±0.10 (5) and 0.35±0.04 (3) for body temperatures of 20, 10 and 5 °C, respectively. Cardiogenic pulsations during apnea visible on plethysmographic pressure traces and theoretical calculations of airway and cutaneous diffusion potentials support the notion that apneic O2 uptake occurs down an open airway by both diffusion and bulk convection.
Ultrasonic Vocalizations Of Flying Bats Monitored By Radiotelemetry
Authors: Lancaster Winston C. , Keating Arthur W. , Henson O. W.
Published: April 2021

Ultrasonic vocalizations of flying bats were effectively monitored with radiotelemetry. We describe a device light enough to be carried by an 11g bat for periods of up to 1h. It transmitted signals adequate for fine frequency analysis within a range of approximately 3 m. Telemetry permitted the recording of constant-frequency pulses free from flight-induced Doppler shifts and without time delays. The difference in frequency between telemetered signals and the same signals detected by a remote microphone was used to calculate velocity and Doppler shifts.

Pulse emission behavior of Pteronotus parnellii in flight was compared with simulated flight on a pendulum. The data showed significant differences in echo bandwidths, constant-frequency pulse durations and interpulse intervals. In flight, pulses and interpulse intervals tended to be shorter and bats maintained echo frequencies within a significantly narrower band. Phases of echolocation that characterized the approach to a target were clearly evident in flight, but not during pendulum swings. Differences in pulse durations and interpulse intervals may be correlated with the integration of wingbeat, respiration and vocalization. The absence of wing motion in simulated flight changes this integration.
Functional Specialization of the Scoloparia of the Femoral Chordotonal Organ in Stick Insects
Authors: Kittmann Rolf , Schmitz Josef
Published: April 2021

The femoral chordotonal organ (fCO), one of the largest proprioceptive sense organs in the leg of the stick insect, is important for the control of the femur-tibia joint during standing and walking. It consists of a ventral scoloparium with about 80 sensory cells and a dorsal scoloparium with about 420 sensory cells. The present study examines the function of these scoloparia in the femur-tibia control loop. Both scoloparia were stimulated independently and the responses in the extensor tibiae motoneurones were recorded extra-and intracellularly.

The ventral scoloparium, which is the smaller of the two, functions as the transducer of the femur-tibia control loop. Its sensory cells can generate the known resistance reflexes. The dorsal scoloparium serves no function in the femur-tibia control loop and its stimulation elicited no or only minor reactions in the extensor motoneurones. A comparison with other insect leg proprioceptors shows that a morphological subdivision of these organs often indicates a functional specialization.
Pigeon Homing: Observations, Experiments and Confusions
Authors: Walcott Charles
Published: April 2021

Homing pigeons can return from distant, unfamiliar release points. Experienced pigeons can do so even if they are transported anesthetized and deprived of outward journey information. Airplane tracking has shown that they make relatively straight tracks on their homeward journey; therefore, pigeons must have some way of determining the home direction at the release site. Manipulating the pigeon’s internal clock causes predictable deviations in their flight direction relative to home. When the sun is not visible, such clock shifts have no effect. This result implies a two-step system: the determination of the home direction and the use of a sun compass to fly in that direction. When pigeons cannot see the sun they use a magnetic compass. The use of compass cues to select and maintain a direction of flight is well understood compared with the uncertainty surrounding the nature of the cues used to determine the home direction when pigeons are released at an unfamiliar site. Because they generally home successfully from any direction and distance from the loft, without requiring information gathered on the outward journey, it seems likely that they use some form of coordinate system. Presumably, a displaced pigeon compares the values of some factor at the release site with its remembered value at the home loft. This factor might be olfactory, it might be some feature of the earth’s magnetic field or it might be something else. There is some evidence that pigeons may use several cues and that pigeons raised in different lofts under different environmental conditions may prefer to use one cue over another. I believe that it is this flexible use of multiple cues that has led to so much confusion in experiments on pigeon homing.
Computations on Metric Maps in Mammals: Getting Oriented and Choosing a Multi-Destination Route
Authors: Gallistel C. R. , Cramer Audrey E.
Published: April 2021

The capacity to construct a cognitive map is hypothesized to rest on two foundations: (1) dead reckoning (path integration); (2) the perception of the direction and distance of terrain features relative to the animal. A map may be constructed by combining these two sources of positional information, with the result that the positions of all terrain features are represented in the coordinate framework used for dead reckoning. When animals need to become reoriented in a mapped space, results from rats and human toddlers indicate that they focus exclusively on the shape of the perceived environment, ignoring non-geometric features such as surface colors. As a result, in a rectangular space, they are misoriented half the time even when the two ends of the space differ strikingly in their appearance. In searching for a hidden object after becoming reoriented, both kinds of subjects search on the basis of the object’s mapped position in the space rather than on the basis of its relationship to a goal sign (e.g. a distinctive container or nearby marker), even though they have demonstrably noted the relationship between the goal and the goal sign. When choosing a multi-destination foraging route, vervet monkeys look at least three destinations ahead, even though they are only capable of keeping a maximum of six destinations in mind at once.
Do Animals Have Cognitive Maps?
Authors: Bennett Andrew T. D.
Published: April 2021

Drawing on studies of humans, rodents, birds and arthropods, I show that ‘cognitive maps’ have been used to describe a wide variety of spatial concepts. There are, however, two main definitions. One, sensu Tolman, O’Keefe and Nadel, is that a cognitive map is a powerful memory of landmarks which allows novel short-cutting to occur. The other, sensu Gallistel, is that a cognitive map is any representation of space held by an animal. Other definitions with quite different meanings are also summarised. I argue that no animal has been conclusively shown to have a cognitive map, sensu Tolman, O’Keefe and Nadel, because simpler explanations of the crucial novel short-cutting results are invariably possible. Owing to the repeated inability of experimenters to eliminate these simpler explanations over at least 15 years, and the confusion caused by the numerous contradictory definitions of a cognitive map, I argue that the cognitive map is no longer a useful hypothesis for elucidating the spatial behaviour of animals and that use of the term should be avoided.
Genetic Basis, Mode of Inheritance and Evolutionary Changes of Migratory Directions in Palearctic Warblers (Aves: Sylviidae)
Authors: Helbig A. J.
Published: April 2021

The genetic basis, mode of inheritance and recent evolutionary changes of migratory directions in birds are discussed on the basis of published and new experimental evidence. Displacement experiments with wild-caught migrants and orientation tests with hand-reared passerines illustrate that inexperienced young birds possess genetic information about the direction and approximate distance of migration, but not about the geographic location of the winter quarters. Hand-raised blackcaps Sylvia atricapilla from east and west of the Central European migratory divide, when tested under identical conditions, exibited population-specific migratory directions in orientation cages. Cross-breeding of birds from these two populations demonstrated an intermediate mode of inheritance of this behavioural character. New data on the orientation of an F2 generation suggest that the directional information is encoded by only a few major genes. Migratory adaptations may have evolved recently, in some cases rapidly, as is illustrated by the establishment of a new migration route of central European blackcaps to winter quarters in the British Isles. This new route is shown (in a captive breeding experiment) to be based on a novel, genetically programmed westnorthwesterly migratory direction. It must have spread from almost zero to 7–11 % frequency in parts of central Europe within only three decades. The novel direction is also inherited phenotypically intermediately; its rapid evolution may be mediated by assortative mating based on differential arrival times at the breeding grounds. The evolutionary flexibility of migratory adaptations is discussed in relation to changes in the environment, both natural and accelerated by man.
Pinpointing ‘Isla Meta’: the Case of Sea Turtles and Albatrosses
Authors: Papi F. , Luschi P.
Published: April 2021

Satellite tracking has recently shown that the very long open-sea journeys of sea turtles and albatrosses share several features, in spite of the different physiological and environmental constraints to which turtles and birds are subjected. The reviews of data obtained by tracking migration and feeding routes show that both sea turtles and albatrosses are able (i) to pinpoint small, isolated targets by following straight courses, (ii) to continue on a bearing at night even when the moon is not visible, (iii) to compensate for wind or current drift and (iv) to return home after experimental, long-distance displacements. Sea turtles and albatrosses seem to rely on a position-fixing capacity which cannot be explained by known navigational mechanisms but might be shared by other animals that display similar feats of open-sea guidance. Future research will further benefit from satellite telemetry and other new techniques applied to experimental investigations.
Studies of Wireworm Populations
Authors: Salt George , Hollick F. S. J.
Published: April 2021

Twenty stations were established in a grass field of 8 acres, and twenty-nine soil samples were examined from each station in the course of 213 years. Wireworms (Agriotes sputator) were distributed among the twenty stations in a non-random manner. In this field, the wireworm distribution was correlated to a highly significant degree with nine factors (loss on ignition, organic carbon, nitrogen, Lolium, Agrostis, Chilopoda, staphylinid larvae, ants and Nematocera) and to a significant degree with three factors (altitude, pH of the soil and Diplopoda). Among these factors, three (the organic content of the soil as measured by loss on ignition, the prevalence of the grass Lolium, and the numbers of staphylinid larvae) were found by analysis to be most significantly correlated with the wireworm distribution. Sixteen stations were set up in a grass plot of 14 acre, and twenty-one soil samples were examined from each station during a period of 3 years. The distribution of wireworms at these stations was markedly non-random throughout the sampling period, some stations being consistently three or four times as heavily infested as others only 5 yd, away. Within this plot the distribution of wireworms was correlated to a highly significant degree with altitude, depth of loam and amount of soil moisture at 3 and at 9 in. depth. It was significantly correlated with the lime content of the soil. Ranunculus was prevalent on an area of low wireworm infestation. Among the factors studied in this plot, the amount of soil moisture at 3 in. depth was most important. It was negatively correlated with the distribution of wireworms. Within the plot, stations having high wireworm populations were infested almost exclusively by Agriotes sputator; those having low wireworm populations were infested about equally by A. sputator and A. ‘obscurus-lineatus’. Four square-yard samples were examined, each in eighty-one quadrats 4 in. square. Within each square yard, the wireworms were not distributed at random and independently, but were markedly aggregated. Separation of the wireworms collected from these samples into three size groups showed that the non-random distribution in square-yard samples was largely due to the small larvae, which were strongly aggregated. The medium-sized larvae were less markedly aggregated. The distribution of the large larvae under grass was not significantly different from a random distribution. To understand the factors controlling wireworm distribution it will be necessary to consider the distribution of the different larval age-groups. Two suggestions are made towards an explanation of the geographical distribution of wireworms in England. Study of the spatial distribution of wireworms raises some of the major problems of ecology and, in particular, illustrates the interdependence of spatial distribution and seasonal succession.
Studies on Tapeworm Physiology
Authors: Smyth J. D.
Published: April 2021

A technique has been elaborated that enabled the plerocercoid larvae of Schistocephalus solidus to be removed from the body cavity of Gasterosteus aculeatus without bacterial contamination. Larvae were cultured in plugged test-tubes under completely aseptic conditions in a variety of balanced salines, glucose salines and nutrient peptone broth. The most successful results were obtained with peptone broth at room temperatures (16-19° C) in which plerocercoids remained active and showed normal behaviour for periods up to 300 days. In ¾ strength Locke’s solution, which was found by experiment to be approximately isotonic with Schistocephalus (Δ =-0.44 ± 0.02° C), the mean period of normal behaviour was 114 days. In the remaining saline and saline-glucose media, the mean viability and period of normal behaviour was considerably less. In the plerocercoid, histological examination revealed that the genitalia are in an immature condition. During cultivation at room temperatures, the genitalia remained in this undifferentiated condition and showed no signs of undergoing spermatogenesis, oogenesis or vitellogenesis. Plerocercoids were induced to develop into sexually mature adults by raising the temperature of cultivation in peptone broth to 40° C. (i.e. the body temperature of the final host in the natural life cycle). Oviposition took place after 48-60 hr. at this temperature, and histological examination revealed that spermatogenesis, oogenesis, vitellogenesis and shell formation had taken place in a normal manner. The viability of artificially matured Schistocephalus was 4-6 days in vitro--a period equivalent to the viability of the adult in vivo. The eversion of the cirris was observed in each proglottid after 40 hr. cultivation at 40° C. During the sexual process the cirris everted and invaginated at the rate of about once per second. Cross-fertilization between segments of the same worm or with segments of another worm was not observed. Except for one specimen in ¾ strength Locke’s solution which underwent spermatogenesis and partial vitellogenesis, larvae cultured in salines or glucose salines at 40° C. died within 1-3 days without further development. Attempts to hatch out the eggs produced by the cultivation of larvae in peptone broth at 40° C. proved unsuccessful. Histological examination revealed that spermatozoa had not been taken into the vagina. It was concluded that the eggs were not fertilized owing to the failure of normal copulation to take place.
The Theory of Alternating Current Measurements in Biology and Its Application to the Investigation of the Biophysical Properties of the Trout Egg
Authors: Rothschild Lord
Published: April 2021

Alternating current measurements in biology are concerned with the resistance and capacitance of the cell membrane, and the resistance of the cell interior. No systematic electrical measurements have so far been made on the cell nucleus.
The Mechanism of Locomotion in Snakes
Authors: Gray J.
Published: April 2021

Among snakes four main types of terrestrial progression have been described: (i) serpentine movement which is observable in all, or nearly all, genera; (ii) concertina movement as briefly described by Wiedemann (1932) in Vipera and Coronella; (iii) crotaline or ‘side-winding’ as seen in Crotalus or Cerastes (Mosauer, 1932a,b); and (iv) rectilinear movement as exhibited by boas and other large types (Home, 1812). The observations described in the present paper have all been made on the common grass snake (Tropidonotus natrix); the evidence to be presented shows that serpentine, concertina or crotaline movements can all be elicited in this genus by appropriate modification of the external forces operating on the body of the moving animal.
The Responses of Onion and Lily Mitosis to Coumarin and Parasorbic Acid
Authors: Cornman Ivor
Published: April 2021

In Allium and Lilium roots, saturated aqueous solution of coumarin produced a disruption of the metaphase typical of many benzene derivatives, viz. suppression of the spindle, splitting and shortening of the chromosomes, with retarded division of the centromere. The resultant polyploid nuclei and binucleate cells resumed division when the roots were returned to water. Saturated solution of parasorbic acid slowed Allium mitosis, but caused no abnormalities. Both coumarin and parasorbic acid eventually prevented the inception of mitosis, and this suppression of prophases persisted for several hours after removal of the agent. The results are in agreement with prior evidence that in some configurations the benzene ring disrupts mitosis whereas the lactone ring inhibits growth.
The Oxygen Consumption of Gasterosteus Aculeatus L. In Toxic Solutions
Authors: Erichsen Jones J. R.
Published: April 2021

A simple apparatus is described with which the oxygen consumption of a small fish may be estimated, first in water and then at successive time intervals in a toxic solution, so that the progressive effect of the solution on the rate of oxygen intake may be graphed.

Chloroform solutions of concentration 1/3000 to 1/5000 gradually depress the respiration rate and are ultimately fatal. A 14/100,000 solution appears to produce a state of anaesthesia in which the oxygen intake is about 30 % normal.

Sodium cyanide solutions bring about a progressive decline in the oxygen intake which is closely accompanied by a decline in the rate of opercular movement. The critical concentration is about 0.00004N, which depresses the respiration rate to 32 % normal in 90 min. At greater dilution the survival time lengthens rapidly. Sodium sulphide solutions give very similar results but are somewhat less toxic than cyanide solutions, and the value for the critical concentrations is about 0.0002N.

Heavy metal salts (mercuric chloride, copper sulphate, lead nitrate) produce at first an increase in the respiration rate. Then the oxygen intake declines, but the rate of opercular movement continues to increase, reaches 180-240/min., continues at this increased rate for some time in the case of dilute solutions and then falls rapidly when the oxygen intake is reduced to 38 % normal.

It is concluded that in the case of cyanides and sulphides, where respiration is inhibited at the tissues, the close agreement between the oxygen intake and opercular movement rate may be attributed to the decline in carbon dioxide production. In the case of the heavy metal salts, on the other hand, where respiration is obstructed at the gill surfaces, it would appear that the carbon dioxide content of the blood is raised so that the respiratory centre is stimulated and the opercular movements increase in speed and amplitude. The continued fall in oxygen intake and accumulation of carbon dioxide maintains this effect for some time, but eventually the fish becomes exhausted, the respiratory movements fail and the fish dies.

The work concludes with some suggestions for further investigation.
Studies on Sterility and Prenatal Mortality in Wild Rabbits
Authors: Rogers Brambell F. W. , Mills Ivor H.
Published: April 2021

The yolk-sac contents were observed to be gelatinous in many embryos of wild rabbits at from 7-to 12-day stages, but particularly at 8 and 9 days. Gelatinous strands were observed in the uterine lumen, often connecting adjoining blastocysts, in 8–12-day stages, but particularly at 8 and 9 days. Gelatinous blastocysts and strands frequently were encountered together in the same uterus. Evidence is adduced that these abnormalities, though tending to occur at slightly earlier stages, are related to the mortality which attains a maximum on the 11th and 12th days. Microscopic examination revealed the presence of a reticulum of fine fibrils in the yolk-sac cavity, the histological characters of which are described. The degree of development of this reticulum varied widely from one uterus to another, and often in the individual embryos of the one litter. The presence of this reticulum, when sufficiently dense, was responsible for the gelatinous character of the yolk-sac contents. The gelatinous strands consisted of felted masses of these fibres and of maternal and foetal tissue debris. The fibrous reticulum was absent from the cavities of the amnion and exocoele. A similar reticulum was present sometimes, though rarely so well developed, in the embryos of tame rabbits. Frequently it was absent. It was shown by histological means that the reticulum was not an artefact. The alternatives, that it was either a micro-organism or a network of organic fibres, remained. Morphologically the reticulum resembled the mycelium of an actinomycete so closely that the possibility that it was an invasive organism belonging to this group could not be ignored. Culture experiments disproved this theory and provided satisfactory evidence that the yolk-sac cavities of tame rabbit embryos containing the reticulum were bacteriologically sterile. Sections of clots of fibrin prepared from rabbit-blood plasma presented a similar histological appearance. The presence of fibrinogen in the yolk-sac fluid of 9-day embryos of tame rabbits was demonstrated by clotting the aspirated and citrated fluid with thrombin. Comparison of the clots formed in parallel series of dilutions of the yolk-sac fluid and of plasma indicated that the concentration of fibrinogen in the former was of the order of 50% of that in the latter. Separation of the fibrin from the residue of the yolk-sac fluid was effected by filtration and repeated washing. The mean weight of dried fibrin obtained per ml. of yolk-sac fluid was 37% of that from plasma and its nitrogen content was 33%. The amount of fibrin in the yolk-sac fluid varied significantly from litter to litter. The mean quantity of nitrogen in the residue of the yolk-sac fluid was 57 % of that in the blood serum. The significance of these results in relation to embryonic nutrition and prenatal mortality is discussed.
The Production-of Fatty Acids in the Alimentary Tract of the Dog
Authors: Phillipson A. T.
Published: April 2021

The significance of fermentation in the large gut of the dog has been investigated. According to the quantities of volatile acids and their relation to body weight, the lower fatty acids do not appear to contribute more than a small portion of the energy requirements of the animal. Evidence is presented to show that the individual acids produced in the large intestine consist largely of acetic and propionic acids and that the amount of butyric present is small. This is the same mixture of acids found where fermentation occurs in the alimentary tract of ruminants, horses, pigs, rabbits and rats. The higher proportion of propionic acid is interesting and suggests that the propionic acid bacteria are normal inhabitants of the large intestine of the dog and possibly of a wide variety of animals.
Transpiration and the Structure of the Epicuticle in Ticks
Authors: Lees A. D.
Published: April 2021

The passage of water through the cuticle of living ticks is greatly influenced by the activities of the underlying epidermal cells. In a previous paper (Lees, 1946) it was shown, for example, that unfed ticks reach a state of equilibrium at a relative humidity of about 90%; and if their water balance is depleted they will take up water through the cuticle when exposed to higher humidities. Furthermore, although exposure to humidities below the equilibrium results in water loss through the cuticle, evaporation is much less rapid than it becomes subsequently if the tick is killed or asphyxiated. It was therefore argued that at low humidities secretion assists in the retention of water. These active processes are only well developed in the unfed tick and become imperceptible after the blood meal has been ingested.

In considering the mechanisms involved in the exchanges of water through the cuticle the assumption was made that, in addition to active secretion, the passage of water, and particularly its retention, is also influenced by the presence of lipoid material in the cuticle. Ticks show great diversity in their powers of resisting desiccation, and this was thought to be accounted for by the specific nature of the waterproofing lipoid. Nevertheless, no direct evidence of such a component was advanced in this paper.
Hovering flight in hummingbird hawkmoths: kinematics, wake dynamics and aerodynamic power
Authors: Warfvinge Kajsa , Johansson L. Christoffer , Hedenström Anders
Published: April 2021

Hovering insects are divided into two categories: ‘normal’ hoverers that move the wing symmetrically in a horizontal stroke plane, and those with an inclined stroke plane. Normal hoverers have been suggested to support their weight during both downstroke and upstroke, shedding vortex rings each half-stroke. Insects with an inclined stroke plane should, according to theory, produce flight forces only during downstroke, and only generate one set of vortices. The type of hovering is thus linked to the power required to hover. Previous efforts to characterize the wake of hovering insects have used low-resolution experimental techniques or simulated the flow using computational fluid dynamics, and so it remains to be determined whether insect wakes can be represented by any of the suggested models. Here, we used tomographic particle image velocimetry, with a horizontal measurement volume placed below the animals, to show that the wake shed by hovering hawkmoths is best described as a series of bilateral, stacked vortex ‘rings’. While the upstroke is aerodynamically active, despite an inclined stroke plane, it produces weaker vortices than the downstroke. In addition, compared with the near wake, the far wake lacks structure and is less concentrated. Both near and far wakes are clearly affected by vortex interactions, suggesting caution is required when interpreting wake topologies. We also estimated induced power (Pind) from downwash velocities in the wake. Standard models predicted a Pind more than double that from our wake measurements. Our results thus question some model assumptions and we propose a reevaluation of the model parameters.