ALBERT

Notes: Résumé Les nerfs cholinergiques vasodilatateurs de l'artère utérine du cobaye ont leur origine dans les ganglions paracervicaux. L'ablation de ces ganglions permit d'évaluer l'importance des nerfs vasodilatateurs dans le cas d'une hyperémie de l'uterus apparaissant durant la grossesse.

Notes: Résumé La perméabilité à l'albumine des vaisseaux capillaires fut caractérisée par le produit PS deRenkin. Cette mesure fut obtenue par une analyse dynamique de la quantité d'albumine contenue dans les interstices de la zone corticale du rein.

Notes: Summary UnfertilizedCiona eggs were centrifuged, stratifying their mitochondria and some other cytoplasmic components. Each centrifuged egg had a mitochondria-free, centripetal clear layer that was contiguous with centrifugal layers containing mitochondria. By cutting centrifuged eggs in two at various levels along the centripetal-centrifugal axis, it was possible to obtain centripetal fragments including virtually no mitochondria, about one-tenth of the uncut egg's mitochondria or about one-fourth of the uncut egg's mitochondria. Most of these centripetal fragments, when fertilized, developed into larvae. However, only the centripetal fragments that included about one-fourth of the uncut egg's mitochondria developed into larvae giving the cytochemical reaction for cholinesterase, a convenient indicator of muscle cell differentiation inCiona. Therefore, the inclusion of a minimum number of mitochondria (more than one-tenth but less than one-fourth the number in the uncut egg) is correlated with muscle cell differentiation in larvae developing from the centripetal fragments. The possible influences of mitochondria and of other cytoplasmic components on muscle differentiation are discussed.

Notes: Summary In laboratory colonies ofLasioglossum zephyrum, derived from unrelated pupae and in nests with identical soil and food sources, guards recognize non-resident conspecifics on the basis of odor discrimination. Odors which are important in this recognition mechanism seem to be individual bee odors. The system of recognition may be one of the following: 1. The guard recognizes the summation of odors emitted by all resident bees, and a non-resident intruder emitting an odor which is not part of this repertoire elicits aggressive responses by the guard, or 2. the guard becomes habituated to the odors of each resident bee, and a non-resident intruder emitting an odor to which the guard is not habituated, elicits aggressive responses.

Notes: Summary 1. Gnathonemus petersii respond to each other's electric organ discharge (EOD) with an “echo” discharge of their own at a latency of about 12 msec. This response persists until interfish distances reach about 30 cm (Fig. 4). 2. Artificial electrical stimuli were used to further characterize the response. Response threshold, latency dependence on stimulus intensity, polarity characteristics (Figs. 5–7), and differential regional sensitivity indicate that “medium” electroreceptors in the anterior region of the animal underlie the response. 3. Response probability depends upon the delay of the stimulus after the last EOD and also upon the instantaneous EOD rate (Figs. 8, 9). The echo response in turn resets the EOD rhythm of the responding animal (Fig. 10). These results suggest that the echo input pathway terminates on the presumed mesencephalic command center.

Notes: Summary 1. The electric organ discharge (EOD) patterns seen in pairs of mormyrid fishes (Gnathonemus petersii) during displays related to aggression and establishment of dominance are described. 2. A new method of reliably separating the discharges of the two fish was used. In this method a fine wire was attached to the tail of one animal (Fig. 1). 3. Discharge patterns were examined at different stages during the characteristic sequence of overt behavioral events which usually occurred after an intruder was put into a tank in which another fish of the same species had been resident for 1 hour or more. The resident attacked the intruder immediately, the intruder being initially unresponsive. After a few minutes, however, the two fish entered into intense, mutual, antiparallel displays (Fig. 2). The displays occurred repeatedly during a period of 0.5–30 min. This period ended suddenly with one of the fish clearly dominant as shown by one-sided attacks and avoiding behavior by the submissive fish. 4. All attacks were accompanied by a smooth acceleration to a high discharge rate which was usually terminated abruptly (Fig. 3). Anti-parallel behavior was accompanied by similar accelerations in both fish. Interdischarge intervals during these high rates changed discretely between those of about 15 msec and those of about 9 msec (Figs. 3–9). Initial attacks before the antiparallel period usually produced no effect or a brief acceleration in the discharges of the attacked animal. Similar attacks when dominance was well established caused a slowing of the discharge rate of the attacked fish. 5. The echo response in which one fish responds to the EOD of another with a discharge of its own at a latency between 11 and 14 msec was seen at all stages of the encounter. This latency corresponded rather exactly to the gap in the interval histogram between the shorter intervals around 9 msec and the longer ones around 15 (Figs. 11, 12). This correspondence led to a degree of avoidance of near synchronous discharges during those attacks which did not cause either slowing or accelerations in the attacked animal (Fig. 11). A degree of synchrony avoidance also occurred during the mutually high discharge rates of antiparallel behavior. This resulted from the phase locking of the two discharge trains which was often present at these times and which was probably due to the echo responses (Fig. 13). 6. Several features of the individual discharge trains and of their interaction were examined during the period of antiparallel activity. This was done in order to see if some critical parameter could be detected which would allow one to predict the winner of the encounter and which might be used as a signal by the fish themselves. No single feature among those we examined was clearly and consistently related to the outcome of the encounter.

Notes: Summary The major releasing stimulus in intraspecific nest defense ofLasioglossum zephyrum is the odor emitted by a non-resident bee. Non-resident bees older than two days emit the releasing odor and elicit aggressiveness by guard bees, whereas younger non-resident bees are accepted more often. Defense motivation is a function of nest age and/or ontogeny. As nests become older and cells are constructed and provisioned, there is a gradual increase in guard aggressiveness, although no one attribute of nest ontogeny (such as cell construction) seems to be a definitive point at which nest defense is initiated, nor is there any specific day after the emergence of the first bee when nest defense begins. The guard plays the major role in rejecting intruders, although other members of the colony may do so if a non-resident bee passes the guard and enters the nest.

Notes: Summary Intraspecific nest defense inLasioglossum zephyrum involves specific agonistic action patterns by guard bees released by non-resident intruders. When guards are not highly motivated, intention movements are exhibited which also occur in the context of more aggressive interactions. Antennation, either mutual or by one bee, usually occurs prior to aggressive movements. Two main action patterns occur when a non-resident bee attempts to enter a nest: (1) the guard blocks the nest entrance with the abdomen, which often leads to backing movements and abdominal thrusts to eject the intruder, (2) the guard assumes a fight posture with head and abdomen extended toward the intruder; from the fighting posture, lunging often results in which the guard moves forward, alternating between head (mandibular) and abdomen (sting) thrusts. Most interactions are one-sided, with the intruder retreating from the guard, but mutual more intense fighting does occur.

Notes: Summary Fundamental properties of the dispersion relations for internal gravity wave modes in stratified shear flows are derived as generalizations of the corresponding well known properties found in the absence of shear. Some problems associated with the expansion of internal wave fields in the normal modes are discussed briefly. Such problems may result from a lack of completeness or of orthogonality of the normal modes.

Notes: Summary Numerical simulation techniques are employed to investigate the propagation of internal waves through an ocean characterized by random fine structure density variations. Fine structure realizations are obtained by summation of random phase Fourier components whose amplitudes are derived from observed fine structure spectra. The results generally confirm the theoretical conclusion that the propagation of high frequency waves with vertical scales in excess of several meters is not seriously degraded by the density fine structure over propagation path lengths of order 100 m.