ALBERT

Notes: Summary 1. We described locomotor activity patterns in fiddler crabs by the frequency distributions of the duration of single activity bouts and of single rests. No significant interrelations between consecutive activity bouts and rests were detectable. The analysis of the frequency distributions led to the conclusion that the patterning of activity behaviour in constant conditions can be described by stochastic processes (Lehmann, Neumann, Kaiser, 1974). 2. Using the very parameters of the analysis we simulated activity patterns with two models. In model 1 the duration of each activity bout or rest is determined at its onset by one stochastic decision using the observed frequency distributions (Fig. 1). In model 2 the transition from one state (activity or resting) to the alternative state is controlled by a series of consecutive stochastic decisions at regular intervals (Fig. 2). 3. The simulated activity patterns produced by the two models using the data of freerunning crabs are similar to the original patterns. They are rather random and give only for short sequences the impression of a weak rhythmicity (Figs. 5, 9, 11). 4. Simulation with the data of the only one crab which displayed a spontaneous circadian rhythm yielded rhythmic patterns despite the fact that no serial correlations and no phase control were fed into the simulation (Fig. 14). 5. Simulation with the data of crabs which were entrained by artificial tides also yielded distinctly rhythmic patterns (Figs. 17, 18). 6. The results of 4. and 5. demonstrate that the preference of a certain duration of the rests is sufficient to organize an activity pattern rhythmically without additional control by an endogenous oscillator. 7. Entrainment of the activity by a Zeitgeber regime was simulated with an extended model 2: The supposed external cycle influences the transition probabilities from activity to resting and vice versa. According to the strength of the external influence the simulation produces more or less strictly synchronized patterns (Fig. 21). 8. The variation in the results of the stochastic simulations demonstrates the effects of chance. Simulations may be used to scan the range of random variations. 9. The involvement and the properties of an endogenous oscillator can not be deduced with certainty from an observed rhythmic pattern only, since the properties of behavioural mechanisms may be sufficient to produce a fairly clear periodicity.

Notes: Summary Extraretinal photoreception is involved in the perception of light used to measure photoperiodic time during the initiation of gonadal growth in a number of birds. Evidence is presented which demonstrates that extraretinal photoreceptors are also involved in measuring photoperiodic time during the gonadal photorefractory period in the goldencrowned sparrow (Fig. 3). Untreated sparrows were able to terminate the refractory condition while being exposed to long dim days (16DL:8D; DL=0.2 lux). However, birds which had their head feathers clipped to allow more light to penetrate through to the brain were maintained in the refractory state under the same lighting conditions. These results demonstrate that extraretinal photoreception is involved in the maintenance of photorefractoriness in birds. It has been suggested that the eyes and extraretinal photoreceptors may both be involved in the initiation of gonadal growth in golden-crowned sparrows (Gwinneret al., 1971). This conclusion was based on the observation that a reduced rate of gonadal growth occurred in sparrows with shielded brains as compared to unshielded controls when both groups of birds were exposed to the same light treatment (i.e. 16L:8D; L=6 lux). The results presented here suggest that at a light intensity of 6 lux, light may have been reaching extraretinal photoreceptors even in birds with shielded brains. Therefore, the eyes may not be involved in testicular recrudescence in this species.

Notes: Summary The roles of certain abdominal muscles in ventilatory behaviour are discussed and illustrated with records of muscular activity obtained mainly from free-swimming animals. The following muscles are shown to be active during normal ventilation (V n): respiratory and anterior dorso-ventrals (RDV and ADV), longitudinal tergal (LT), diaphragm, sub-intestinal and adductors of the anal appendages (VADP). The posterior dorso-ventral, lateral primary longitudinal sterno-pleural, and dorso-ventral oblique muscles were found to be inactive duringV n. TheRDV, ADV, LT andVADP are also active during ventilatory movements other thanV n.RDV activity is shown to be more variable in the free-swimming animal than recordings from dissected and restrained preparations previously suggested. Activity in theADV duringV n shows a reciprocal relationship with that in theRDV. Postulated control elements in larval ventilation are found to parallel many described in other ventilatory systems and motor rhythms generally.

Notes: Summary 1. Stretch applied to the ventricle, or contraction of the heart, sets up afferent activity (presumably of a sensory nature), in the cardiac nerve ofBusycon canaliculatum. Such afferent activity, elicited by either mechanical or electrical stimuli, can be traced through the pseudoganglion, the cardiac nerve, and the visceral ganglia to the parietal-visceral connectives. 2. In response to the induced afferent activity, efferent activity appears and can be recorded from a teased-out intracardiac branch of the cardiac nerve. 3. Section of the cardiac nerve distal to the visceral ganglia may lead to an increase in amplitude of compound peaks in the extra- or intraventricular cardiac nerve. 4. Electrical activity ceases in the intraventricular branches of the cardiac nerve, after severing the cardiac nerve distal to the pseudoganglion. 5. The pseudoganglion is possibly a reflex center for the intraventricular branches of the cardiac nerve, but there is an inhibitory central influence on the reflexes. The inhibitory influence is probably exerted by the visceral ganglia.

Notes: Summary The morphology and innervation of the pterothoracic scolopal organs ofNepa cinerea were studied using stereoscan and methylene blue staining. The behavior ofNepa cinerea when excited by sounds was observed and analyzed. When the animals are exposed to sound they assume a thanatosis, whose duration and habituation are dealt with in this study. Through exstirpation experiments it was possible to prove that the thoracic scolopal organs are the sound receivers that evoke death feigning. By extracellular recording from the nerve of the scolopal organs it was directly confirmed that they are sound receivers. The threshold curves of the organs were determined. One sensory cell is more sensitive than the other to the extent of 12,5 dB. Both have a logarithmic intensity characteristic, although the rate of incline however differs. With longer stimuli the spike activity of both units decreases in a phasic-tonic way.

Notes: Summary The input of a large statocyst interneuron in the oesophageal connectives of the crabScylla serrata has been limited to the thread hair receptors of a single statocyst and the output of this interneuron has been used as a monitor of thread hair activity to test the transduction properties of the statocyst. The vertical canal of the statocyst abstracts the magnitude and direction of the rotational component in the plane in which it lies. The orthogonal components thus abstracted by the two vertical canals may be used very simply by the animal to compensate for any rotation about the horizontal axes using effector components limited to pitch or roll. The canal and thread hair system is insensitive to short duration linear accelerations but is significantly influenced by gravity such that it operates effectively only over a limited range of positions. The response to a given sinusoidal oscillation varies with the initial position of the crab.

Notes: Summary 1. The innervation pattern of the intrinsic foregut musculature was determined using physiological methods in blue crabs (Callinectes) and spiny lobsters (Panulirus) (Tables 1, 2). The distributions of individual axons were observed in methylene blue stained preparations and their physiological effects were observed by recording excitatory postsynaptic potentials (EPSPs) in various muscles while stimulating the axons directly or while the stomatogastric ganglion was active (Figs. 4–8). 2. InCallinectes the gastric mill muscles were all singly motor innervated, while many of the pyloric muscles were multiply innervated with as many as 3 motor axons to a single muscle (Table 1). InPanulirus the pyloric muscles also showed multiple innervation with a maximum of 5 axons to a single muscle (Table 2). 3. EPSPs varied in shape and amplitude from one muscle to another in both species even when two or more muscles were innervated by the same axon (Fig. 4). InPanulirus variation of EPSPs along individual muscle fibers was observed, indicating non-uniform innervation. 4. InCallinectes the variation in size of the EPSP from one recording site to another was correlated with degree of facilitation and with sarcomere length. Fibers with small EPSPs generally showed more facilitation and relatively shorter sarcomere lengths than fibers with large EPSPs (Table 1). However, instances were found in which the usual correlation did not hold. 5. Also in the blue crab a correlation was found between resting sarcomere length and contractile properties with short sarcomered fibers giving faster contractions than longer sarcomered fibers, as in other crustacean muscles. 6. The complex variety of muscle fiber types and EPSP properties apparently serves to translate the bursts of impulses from the stomatogastric ganglion into the necessary stomach movements. 7. Comparison of the innervation patterns of the gastric mill and pyloric regions suggest that the innervation patterns may be related to the functional roles of these two regions. Multiple innervation of the pyloric region allows rapid depolarization of the muscles to be achieved with a comparatively low frequency of impulses in each axon.

Notes: Summary 1. A pair of thermoreceptor units was identified in the sensilla coeloconica at the tip of the antennae on the mosquito,Aedes aegypti. 2. One thermoreceptor was warm-sensitive and responded with a phasic-tonic increase in spike frequency to sudden increases in temperature. The second thermoreceptor was coldsensitive, responding with a phasic-tonic increase in spike activity to sudden decreases in temperature. 3. The mean tonic spike activity of both the cold and warm receptors increased with increasing temperature to a peak of 30 imp/sec at 26

Notes: Summary 1. Individual proprioceptive campaniform sensilla of tibial Group 6 in the cockroachBlaberus discoidalis were stimulated by combinations of proprioceptive and punctate stimuli. 2. Punctate stimulation during a proprioceptive discharge increased the response rather than decreasing it, indicating that proprioceptive stimuli indent, rather than bulge, the cap of the sensillum. 3. The magnitude of the indentation associated with a strong proprioceptive discharge was estimated from compliance and sensitivity measurements to be in the range 10 to 50 nanometers. 4. The excitatory strain of the tibial cuticle appears to be compression perpendicular to the long axis of the cap of the sensillum. We suggest that the elaborate structure of the cap cuticle serves to amplify the tibial cuticular strain to squeeze the terminal of the dendritic sensory process.

Notes: Summary 1. Cine films of fiddler crabs (Uca pugnax) walking sideways on land were analysed frame by frame in order to study the co-ordination of the legs both during normal walking and following amputation (induced autotomy) of one of the 3rd pair of legs. 2. Although the average gait of unoperated animals approximates to an alternating tetrapod rhythm, equivalent to the alternating tripod gait of insects (Figs. 3–7), the stepping order of legs on leading and trailing sides of the animal is different. The dominant sequence on the leading side is 2435 (legs numbered from front to rear), that on the trailing side 2534 (Table 1), the chelae (leg 1) being usually held off the ground. 3. Stepping parameters also change with walking speed (Figs. 8, 10), the most clear-cut of these changes being the reduced relative duration of the power stroke at high walking speeds. At low walking speeds, clear-cut metachronal co-ordination is sometimes seen in trailing legs (Fig. 9), but the data nevertheless do not fit Wilson's 1966 metachronal model for insect locomotion. 4. Amputation of one of the 3rd pair of legs causes adaptive changes in the gait. The most obvious of these changes are that the chelae are now frequently used in walking and legs 4 and 2 on the operated side of the animal now alternate whereas before they moved together (Figs. 11–13, Table 2). Evidence is presented to show that these changes are brought about by the changed sensory input and are not due either to the effects of axon section on motorneurone electrical excitability, or to the animal walking more slowly and using a different but normally occurring gait.

Notes: Summary 1. The temporal characteristics of the muscle potentials and of the action potentials of the excitor and the inhibitor efferent nerves of the claw opener muscle and the corresponding muscle tension were recorded simultaneously during reflexly evoked claw opening in the undissected crayfish. 2. Contraction was initiated by a high-frequency burst of excitor, and often concurrent inhibitor, discharge but could then be maintained by continuing excitation at about half the frequency. 3. Paired action potentials were generated by both the excitor and the inhibitor; there were also many sequences of intervals of identical length between successive excitor impulses. 4. The results suggested that concurrent excitor and inhibitor discharge enhances the resolution of muscle tension control and that single presynaptic sources might selectively activate distinct populations of muscle fibers and hysteretic phenomena.

Notes: Summary 1. The anatomical and neurophysiological basis of limb elevation at the basiischiopodite joint during locomotion, resistance reflexes, activation of cuticular stress detector 1 (CSL1) and production of the autotomy fracture was studied. 2. Scanning electron micrographs of the basi-ischiopodite interior revealed that the fracture plane consists of a line of tiny perforations in the cuticle (Fig. 3 A and B), which render the limb particularly susceptible to a distorting force concentrated at a single point along the plane. 3. Both the larger anterior levator (AL) and the smaller posterior levator (PL) can elevate the basi-ischiopodite. Force applied to the AL tendon is transmitted via elastic elements to a thin region of cuticle along the fracture plane and can cause the limb to fracture; force applied to the PL tendon is not transmitted to the fracture plane. The levator tendons are mechanically linked at their insertions so that contraction of PL alters the manner in which the force of AL is applied at its tendon insertion (Fig. 5). 4. AL and PL are simultaneously active in walking and resistance reflexes although they possess no shared innervation. The levators are antagonized in both motor patterns by the depressor muscle group. 5. Autotomy elicited by injury to the limb activates large phasic units in the AL nerve; activity in the PL nerve is simultaneously suppressed. In structural terms the inactivity of PL would result in the AL tendon bracing against the internal fulcrum (Fig. 4 A) in an orientation favorable for the transmission of force to the fracture plane. 6. Both levators are activated by stimulation of CSD1. This receptor does not evoke autotomy and instead may regulate the force exerted by the levators in such a way as to relieve stress in the cuticle distal to the AL tendon insertion when the integrity of the fracture plane is threatened.

Notes: Summary Recent studies have indicated that intense short wavelength stimulation in flies converts rhodopsin to a longlived metarhodopsin while decreasing visual sensitivity and electroretinographic (ERG) responsivity. Long wavelength stimulation reverses both visual pigment and ERG alterations. In this study of ERG's in white-eyedDrosophila, spectral sensitivities were obtained following intense visible and ultraviolet short wavelength stimuli. Both stimuli decreased sensitivity to all wavelengths while ultraviolet light also selectively decreased ultraviolet sensitivity (Fig. 1). These results isolated three sensitivity components contributing to the ERG in flies: (1) the dark adapted sensitivity (Fig. 1); (2) the residual sensitivity remaining subsequent to intense ultraviolet stimulation (Fig. 1); and (3) the ultraviolet sensitivity specifically abolished by intense ultraviolet stimulation (Fig. 2). Further evidence shows that the three components are probably receptor-specific; the first two resemble recent fly receptor spectral sensitivity data (e.g. Eckert, 1971) while the third represents a separate ultraviolet receptor. Linear reciprocity of time and intensity to alter the ERG responsivity was found over considerable ranges for long wavelength (Fig. 3) and short wavelength (Fig. 4) induced responsivity alterations. ERG action spectra were obtained for altering responsivity (Fig. 5). The action spectrum for decreasing responsivity was roughly parallel with the dark adapted spectral sensitivity for wavelengths below 500 nm. The action spectrum for reestablishing responsivity had a peak near 570 nm and agreed with previous determinations of spectral characteristics of fly metarhodopsin. The action spectra determined were probably based on photopigment interconversions in the 1–6 receptor system. Long wavelength reconversion of metarhodopsin to rhodopsin may explain the high ultraviolet and low red sensitivities and the functional significance of red eye color pigments in flies.

Notes: Summary UnrestrainedGymnotus were electrically stimulated with a model fish (Figs. 1, 2) producing artificial pulses at predetermined delay to each electric organ discharge (EOD). Stimulus field measurements were made over the rostral surfaces of highest electroreceptor density (Figs. 4 and 5). 1. Four responses to discharge-triggered stimulus trains were indentified: frequency increase; frequency decrease; ‘off’; ‘jamming avoidance’ (Figs. 7–9). 2. Offs occurred at highest threshold at all EOD/stimulus delays but the other response types appeared with a probability which was a function of this delay (Figs. 10, 11). Frequencydecrease was the commonest response to pulses triggered within the fish's EOD, whereas jamming avoidance wasonly seen for signals arriving within the last 5 ms of the interpulse interval. 3. Threshold responses were given in the majority of cases to the onset of the stimulus train and then, after an approximate 20% amplitude increment, to the offset (Fig. 12). In contrast, off thresholds were lowest to stimulus offset at very short delay. 4. Thresholds for the frequency transient responses (Figs. 13, 14) display a 100∶1 variation within the EOD interval. Values are lowest just before and during EOD (ca. 10 ΜV/cm) and at maximum immediately after it (ca. 1 mV/cm). The threshold remains high for the first half of the interval but then drops rapidly to the low level at about 12.5 ms. The off curve (Figs. 13, 15) follows a similar time course but all thresholds are higher. 5. It is argued that the behavioural threshold variation points to the existence of an internal filter which limits the central flow of electroperceptive information to the time period when input from the fish's own active electrosensory system is ‘expected’. 6. It is furthermore suggested that the EOD of interactingGymnotus might show specific latency relationships if the threshold variations were used to maximum benefit during social behaviour. Some preliminary data are presented which support this hypothesis and demonstrate a preferred latency of about 13 ms in aggressive fish. The relative advantages and disadvantages for the electrosensory systems of the two interacting animals are discussed (Figs. 18, 19) and it is shown that the fish responsible for the observed latency relationship can ‘jam’ the electrolocation system of its partner while simultaneously protecting its own electrosensory input from interference.

Notes: Summary Barn owls can learn to remember complex noise spectra and distinguish them from slightly different spectral patterns.

Notes: Summary 1. The responses of single acoustic neurons to sound stimuli were recorded by capillary microelectrodes at three sequential stations (the receptors, the ventral cord, and the supraesophageal ganglion) of the auditory pathway of the tettigoniid speciesDecticus verrucivorus. 2. To characterize the responses to sound stimuli varying in intensity, frequency, direction, and duration, the following four basic measures were used: response fields (threshold and constant-response curves vs. frequency), intensity characteristics, directional diagrams, and the time course of the neuronal discharge. These measures are employed to compare both neurons at each station and those at different levels, so that the progressive development of neuronal information processing can be followed from the receptors to the brain. 3. At the receptor level two groups of neurons can be distinguished; on the basis of general morphological comparisons their origins are ascribed to the crista acustica (group a) and the intermediate organ (group b) (Fig. 2). 4. Receptor cells of group a differ among themselves in characteristic frequency and threshold. Bach carries out a precise coding of intensity and direction in its nearthreshold region (Figs. 1, 3, 5 and 6), but with stimuli more than about 30 dB above threshold, the response saturates. The response areas of different cells overlap so that, taken as a whole, they ensure relatively precise transduction of the above-mentioned stimulus parameters over a wide range of frequencies and intensities. 5. Group-b receptor cells (intermediate organ) are considerably less sensitive to changes in stimulus frequency, intensity, and direction (Figs. 2 and 10). Like those of group a they respond nearly tonically to stimuli sufficiently above threshold (Figs. 7 and 11), though with long stimuli a slight initial phasic component is discernible (Fig. 8). 6. The neurons of the ventral cord receive synaptic input from several tympanic units of the same side, and in many cases informations of the opposite side as well. The observed unilateral and bilateral effects can be brought about by facilitation and inhibition. As a result of this complex integration the discrimination of certain sound parameters available in the receptor-cell responses can, at the ventral-cord level, either be enhanced considerably or be degraded. 7. Whereas frequency selectivity at the higher levels is severely degraded in comparison with that available at the receptor level (Figs. 13, 14, 15 and 29), the precision of intensity and direction coding is distinctly enhanced (Figs. 17, 18, 30 and 31). The response patterns recorded inchide those of phasic units, tonic units, and intermediate forms, as well as units which alter the pattern with stimulus conditions. Several of these are well matched to specific features of the stridulation sounds of the species (Figs. 20 and 21). 8. As far as the processing of frequency and intensity is concerned, only quantitative differences—no fundamental or qualitative differences—were observed in comparisons of the ventral cord and the supraesophageal ganglion (Figs. 24 and 26). With respect to the coding of direction and form of the response pattern, however, characteristic novel units are found in the supraesophageal ganglion (Figs. 25, 27, 28 and 33). Finally, the extent to which “recognition filters” exist at the level of the ventral cord and the supraesophageal ganglion is discussed in terms of the known aspects of acoustic behavior.

Notes: Summary Gross locomotor activity, as well as the movements of single walking legs, were monitored in intact and surgically altered crayfish (Procambarus clarkii). Section of the circumesophageal connectives (CEC) abolished the circadian activity rhythm in both the first and fourth pair of walking legs (Figs. 1–3), while section of the nerve cord between the third and fourth thoracic ganglia abolished rhythmicity in only the fourth pair (Fig. 4). Bilateral ablation of the eyestalks led to a several fold increase in total daily activity and caused the animal to be continually active; however, quantitative measurements of the locomotor activity revealed that a circadian rhythm in the level of activity persists for 6–12 days following eyestalk removal (Figs. 7, 8, 13, 14). These results suggest that the circadian oscillation for the locomotor rhythm originates in the supraesophageal ganglion and is coupled to thoracic locomotor centers via axons in the CEC. The activity rhythm of eyestalkless animals could also be entrained to a light cycle even after ablation of the caudal photoreceptor; however, certain features of entrainment were altered (Figs. 9–12). Thus, although the eyestalks are not required for rhythmicity, eyestalk structures apparently do participate in entrainment.

Notes: Summary The circadian rhythm of the ERG response to a standard light pulse presented once per hour was monitored in both intact and surgically altered crayfish (Procambarus clarkii). Section of the circumesophageal connectives did not interfere with the ERG amplitude rhythm, or its entrainment (Fig. 2); however, rhythmicity was abolished if the optic tract was severed (Figs. 3, 4). These results suggest that the circadian oscillation originates in the supraesophageal ganglion, and is coupled to the eyevia axons in the optic tract. These conclusions were supported by the results of experiments in which the brain was surgically manipulated. Bisection of the brain at the midline eliminated the ERG amplitude rhythm in both eyes, while splitting the brain slightly off-center left the rhythm in the eye associated with the larger half of the brain unaffected (Figs. 8, 9). Histological examination of the operated brains suggested that the olfactory-globular tract may be the pathway by which the circadian oscillation reaches the eyestalk. Finally, the results of bilateral recordings of the ERG amplitude from both intact and operated animals suggested that the rhythms in the two eyes are coupled by a central neural mechanism (Figs. 1, 7, 8).

Notes: Summary 1. Larvae of the flesh-flySarcophaga argyrostoma were exposed to ‘skeleton’ photoperiods consisting of two unequal pulses of light (asymmetrical skeletons) or two equal pulses of light (symmetrical skeletons) per 24 h period. Asymmetrical skeletons (‘night interruption experiments’) revealed two apparently light-sensitive phases within the night, the second, occurring about 9 h after ‘dusk’ in all regimes, being thought to correspond to the photoinducible phase (Φ i) of the photoperiodic oscillator (Fig. 1). 2. Symmetrical skeletons consisting of two 1 h pulses of light closely simulated the diapause-promoting effects of complete photoperiods of the same duration up to about 10 h. Skeletons longer than 16 h were again diapause-promoting in contrast to the diapause-averting (long day) effects of corresponding complete photoperiods. The incidence of diapause was reduced in the ambiguous symmetrical skeletons close to 12 h (in the ‘Bistability Zone’) (Fig. 3). 3. The ambiguity of symmetrical skeletons in the ‘Bistability Zone’ was eliminated by transferring cultures from continuous light (LL) into regimes consisting of two 1 h pulses placed 11 h apart. When the shorter interval (11 h) was ‘seen’ first after theLL-DD transition, long-day effects (low incidence of diapause) were observed; when the longer interval (15 h) was ‘seen’ first short-day effects (high diapause) were observed (Fg. 5). These results are consistent with the hypothesis that the photoperiodic oscillator is damped out by light periods of more than 12 h and resumes its motion on transfer to darkness.

Notes: Summary 1. Echolocation sounds of the batRhinolophus ferrumequinum were played back to the bat as artificial echoes shifted in frequency by a few kHz (0–4 kHz) without distortion of the amplitude and frequency pattern of the sound. The simulated Doppler shifts in the echoes were modulated either sinusoidally or in step functions. 2. The bats did not compensate for frequency shifts within one sound, but in the sounds subsequent to the introduction of the shift. 3. Responses to symmetrical sinusoidal modulations of the echo from −2 kHz to +2kHz demonstrate that in the dynamic situation the bat compensates for positive frequency shifts and ignores negative frequency shifts (Fig. 2). Asymmetrical sinusoidal modulations between 0 Hz and different positive frequency shifts (1, 2, 3, and 4 kHz) yielded amplitude and phase response curves for modulation frequencies between 0.01 and 2 Hz (Fig. 5, 6). The response to step functions gave the time course for positive and negative changes of the frequency shift (Fig. 7). 4. The Doppler compensation system shows nonlinearities: The response of the system depends on the sign of the frequency shift change. Positive changes of the frequency shift in sinusoidal modulations are optimally followed by the system, when it is considered as a sampling system, in which the pulse repetition rate is the sampling rate. The response to negative frequency shift changes is much slower (Fig. 6). With an increase of the modulation frequency the response is DC-shifted. The amplitude and phase response curves depend on the amplitude of the frequency shifts presented in the modulation (Table 1, 2). 5. The maximum compensation between two succeeding bat orientation sounds was 1400 Hz, giving a frequency change of about 10 Hz/msec. This value is about the same as the minimum frequency modulation of the constant frequency portion of the sound detected by the bat. 6. The dynamic properties of the Doppler shift compensation system are discussed in the context to neurophysiological findings on the hearing system of the bat.

Notes: Summary The establishment of the characteristic adult flight and its motor pattern has been followed behaviourally and electrophysiologically in locusts of exactly known ages. In the last two larval instars there is repetitive firing in the flight muscles but the alternation of antagonists typical of adult flight is not present (Pig. 3). Alternation can first be seen late in the last larval instar and the full adult pattern is recognizable in most animals by day 3 of adult life. Competent flight behaviour is established by day 4 or 5. In this period the coupling between elevator and depressor neurones improves and the pattern stabilizes (Figs. 4 and 6) but the time course of the whole process varies considerable between individuals. After this the only major change is an increase in wingbeat frequency from about 15–20 Hz at fledging to 25–35 Hz in the second or third week (Fig. 5). Fixing the wings immovably at fledging, so eliminating normal sensory feedback and practice, does not prevent the co-ordinated pattern from developing (Fig. 8). Muscle firing frequency with the wings fixed remains in the range 13–20 Hz throughout life, which may represent the natural frequency of the intrinsic oscillator (Fig. 10). Input from all the sense organs of the wings has a direct effect on the motor pattern in young animals (Fig. 9) and it is suggested that the increase in wingbeat frequency is due to changes in the phasic sensory input from the wings as the muscles grow and the cuticle thickens.

Notes: Summary The Lobular Giant Movement Detector neuron (LGMD) runs from the lobula of the locust to the protocerebrum, where it synapses with the Descending Contralateral Movement Detector neuron (DCMD) which in turn projects to thoracic motoneurons. The synapse between the two interneurons has been examined physiologically. The DCMD spike follows that of the LGMD without failure at the highest firing frequencies (c. 300 ips) attainable (Fig. 1). After the optic lobe and brain are desheathed, chemical transmission in the visual pathway fails and is subsequently restored in low and high Ca++ salines respectively. The LGMD/DCMD synapse transmits normally throughout this sequence, when the presynaptic axon is stimulated electrically (Figs. 2, 3). Similarly, chemical transmission through the visual pathway, but not the LGMD/DCMD synapse, fails when cooled to around 8°C (Fig. 4). A small potential is seen inside the presynaptic (LGMD) terminal when the DCMD is fired antidromically, and is apparently transmitted electrotonically across the synapse (Fig. 5). Post-synaptically, the potential recorded in the DCMD integrating segment during orthodromic transmission can be demonstrated to be composed of two components; a 40 mV PSP, similar to the presynaptic action potential in waveform, and a small-amplitude axon spike transmitted passively from the DCMD initiation zone (Fig. 6). The DCMD axon spike fails when the PSP is reduced by between one-fifth to one half of its normal amplitude; this occurs when two LGMD spikes follow one another within 4 ms or less (Fig. 7). The synapse is concluded to be electrotonically transmitting, of a wide-band or high-pass nature, and perhaps partially rectifying.

Notes: Summary Within the fifth abdominal segment of intact locusts a group of dorso-ventral expiratory muscles and one inspiratory antagonist display alternating ventilatory patterns of three basic types. Accelerated movements in the dorso-ventral plane are supported by isometric activity of the intersegmental muscles which prevent extensions in the longitudinal axis. The intersegmental coupling of ventilatory motor patterns is strict during strong ventilation and loose and more metachronal with weaker pumping movements. In resting animals ventilatory rhythms are discontinuous and the long intervening pauses are interrupted by miniature inspirations only. Pumping series have a tendency to prolong the later ventilatory cycles, and interfering rhythms of different pumping types occur. Low concentrations of atmospheric CO2 up to 3 % do not accelerate ventilatory rhythms. Afferent activity from proprioceptors could be related to ventilatory motor bursts and stimulation of the sensory nerve produces inspiratory bursts via the segmental ganglion. The neuronal mechanisms of synergistic and antagonistic muscle control as well as the segmental and intersegmental coordination and the effect of autonomous ganglionic oscillators in ventilation are discussed.

Notes: Summary Light-induced potentials were recorded intracellularly from the axons of the monopolar neurons L1 and L2, in the eye ofCalliphora erythrocephala. 1. The receptive fields of these secondary neurons were determined for various wavelengths of the stimulus light (Figs. 1 and 2). No differences associated with the different wavelengths were found. 2. Curves of responsevs. intensity were recorded for different wavelengths (Figs. 3 and 4). These differed only in their position along the intensity axis. It follows that the receptor type controlling inhibition has the same chromatic properties as the R1–R6 system, which constitutes the excitatory input channel.

Notes: Summary Photoperiodic testicular growth in House Sparrows (Passer domesticus) exposed to long days (16 hrs) of orange-red light ({ie205-01}600 nm) is exclusively controlled by extraretinal photoreceptors in the brain; the eyes are not involved. Careful reconsideration of previously published data from this and other bird species does not support a role for the eyes in photoperiodically significant photoreception.

Notes: Summary 1. Calliphora erythrocephala lifted its antennae during walking. On a horizontal walking plane the angleδ between the hind edge of the head and the longitudinal axis of the antennae amounts to nearly 20° in the walking fly and to 7° in the resting fly. The mobility of the joint between scapus and pedicellus is much higher than the mobility of the head-scapus-joint. 2. Immobilization or amputation of the antennae diminish the ability of the free walking fly for gravity reception (Figs. 2–4). A condition for gravity reception by the antennae is the mobility of the scapus-pedieellus-joint. The joint between head and scapus is unimportant in gravity reception (Fig. 5). The bristles inserted dorsally at the scapus (ScBo in Gewecke, 1967b) are involved in gravity reception. Elimination of these bristles causes an extension of the distribution of the walking directions if the mean walking direction of each single intact fly differs less than 10° from the negative geotactic basic direction (Table 2). 3. While fixed walking flies are rotated around their transversal axes, the positionδ w of the antennae (δ w = the angle between the hind edge of the head and the length axis of the antennae) depends on the inclination of the flies (Fig. 7). These angles vary between 12 and 20° in animals with immobilized head and between 15 and 24° in flies whose abdomens have been additionally immobilized. The position of the antennae loaded by a weight on the funicle is independent on the inclination of the flies during the rotation around their transversal axes.δ loaded is great as the walking position of the unloaded antennae in flies walking horizontally. Cutting the bristles of the scapus which overtop the pedicellus (ScBo in Gewecke, 1967b) causes an increase of the amplitude of the lift-movement for all inclinations. But after this operation the position of the antennae is independent on the inclination of the fly's length axis (Fig. 9). There is also no correlation between the amplitude of the antennae lift-movement and the inclination if the fixed walking flies can only move their antennae in the joint between head and scapus (Fig. 10). This joint is therefore unimportant for the mechanism of gravity reception in fixed walking flies. 4. The lift-movements of the antennae are a condition for the mechanism of gravity reception in which antennal sense organs are involved. The scapus bristles are involved in this mechanism by limiting and determing the extent of the lift-movement. On contrast to the known principles of gravity reception in insects, an active movement of a part of the body (the antennae) is a condition for gravity reception in flies.

Notes: Summary 1. MaleDanaus chrysippus butterflies the larvae of which have been raised indoors on their natural foodplants (Asclepias) lack the pyrrolizidinone pheromone (Fig. 1, I) which is known from the hairpencils of field-caught butterflies. 2. MaleD. chrysippus have been observed actively approaching withered parts of aHeliotropium plant in Kenya. These observations could be repeated in the laboratory. On the plants, the males suck extensively. 3. A pyrrolizidine alkaloid (Fig. 1, II) has been isolated and characterized as lycopsamine from thisHeliotropium species. 4. Significant and up to “normal” amounts of I are found in the hairpencils after the indoors-raised males were allowed to: a) suck on withered and remoistenedHeliotropium, or b) feed on a methanol extract ofHeliotropium, or c) feed on a solution of alkaloid (II) isolated fromHeliotropium (see Table 1, Fig. 2). It therefore appears that substance II is a dietary precursor of I. 5. Electroantennogram recordings revealed the presence of antennal olfactory receptors for both substances I and II, as well as for the odor of the withered and remoistenedHeliotropium (Fig. 3). 6. Experiments in which radiolabelled compounds were administered toD. gilippus berenice males also suggest that the pyrrolizidine pheromone (I) is biosynthesized from an exogenous alkaloid precursor.

Notes: Summary The pigment cells of the compound eye of the shrimps (Crangon crangon andC. allmani) were studied by electron microscopy (SEM and TEM) and microspectrophotometry. The compound eyes of these species contain light-absorbing and -reflecting pigments contained in granules, located in 5 different cells. The light absorbing pigment granules (light screen) are situated in (1) the distal pigment cells, (2) the retinular cells, (3) the basal pigment cells. The reflecting pigment granules are located in (4) the distal, and (5) the proximal reflecting pigment cells. Another innominate cell type investing the ommatidia contains vacuoles without pigment content. The innominate cell type, and the basal absorbing pigment cell (3) listed above, have not earlier been reported for a crustacean species. Measurements of the spectral absorption on sliced and squashed ommatidia show that all components of the light screen have an increased absorption in the wavelength regions 400–450 nm and 530–570 nm, probably due to xanthommatin and ommin. The spectral absorbancy of the reflecting pigment cells were not determined. Similar cells in other species are known to contain pteridines.

Notes: Summary 1. Intracellular microeleotrode recordings were obtained from somata of the pre- and postsynaptic neurons of each of four neuron pairs in the stomatogastric ganglion ofPanulirus argus. The microelectrodes were incorporated into a bridge circuit, permitting simultaneous recording and current passing. 2. The following cell pairs were investigated: I. Pyloric Dilator—Pyloric Neuron (PD-PY); II. Anterior Median—Gastric Neuron (AM—GM); III. Large BPSP—Lateral Cardiac or Posterior Gastro-pyloric (EX—LC/GP; IV. Large EPSP—Gastric Mill (EX—GM). The postsynaptic effects of current-induced variations in presynaptic membrane potential were studied in each neuron pair under a variety of experimental conditions. 2. In two cell pairs, the PD—PY and the AM—GM, action potentials initiated antidromically in the presynaptic element did not evoke postsynaptic potentials. If the postsynaptic neuron was simultaneously depolarized through the soma electrode postsynaptic potentials were observed. It is suggested that in the normal functioning of the ganglion local presynaptic depolarizations as well as spikes contribute to transmitter release. 2. In the EX—GM and the EX—LC/GM cell pairs, presynaptic depolarization that did not initiate action potentials nevertheless evoked postsynaptic inhibition and hyperpolarization for as long as the presynaptic current was maintained. Control experiments showed that presynaptic hyperpolarization had no postsynaptic effect. 2. The hyperpolarizing effect of presynaptic depolarization could be blocked by picrotoxin in parallel with blockade of other IPSPs in the ganglion. 2. The experimentally induced voltage changes in the presynaptic terminals are probably comparable to those resulting from synaptic input to the neuron. These experiments support the hypothesis that, in life, depolarization of presynaptic terminals that are subthreshold for action potentials may facilitate or evoke transmitter release. Such presynaptic, nonspike potentials may play a significant role in the modulation of synaptic transmission in neuropil.

Notes: Summary Angular sensitivity functions for light and dark-adapted locust retinula cells have been measured. The angular sensitivity for light-adapted cells follows a Gaussian function but in the dark-adapted condition the measured function is broader than Gaussian at its base. Acceptance angles for light-adapted cells are 1.5°±0.2° (horizontal), 1.4°±0.1° (vertical) and for dark-adapted cells, 2.4°±0.5° (horizontal) and 2.5°±0.4° (vertical). These values are significantly smaller than those previously reported and show the locust eye to be closer to its theoretical limit of resolution than was previously indicated. The angular sensitivity of light-adapted cells agress well with the minimum resolvable stripe period reported by those authors refuting anomalous resolution.

Notes: Summary Jet-propulsion in dragonfly larvae is achieved by the rapid ejection of water from a specialised rectal chamber via the anus, at a frequency of up to 2.2 cycles/s. Movement, forward thrust and muscular activity have been recorded in restrained and free-swimming larvae. Forward thrusts of up to 1.5 g wt result from the expiratory phases of cycles lasting 0.1 to 0.4 s. Swimming velocities are in the order of 10 cm/s. The following muscles are shown to be active during expiratory phases of jetting: anterior, posterior and respiratory dorso-ventrals; primary and secondary longitudinal tergals; lateral primary longitudinal sternopleural; dorso-ventral oblique; ventral adductors of the anal appendages. The sub-intestinal muscle is active during the inspiratory phases of jetting. Activity recorded is compared with that found during normal ventilation. The larval jet-propulsive mechanism is compared with that of certain cephalopods and found to be very effective for the larva's relatively small size.

Notes: Summary Electrophysiological recordings were made from single olfactory cells on the antennae of both sexes ofHylobius abietis L. Cells responding to olfactory stimuli were found to be restricted to discrete regions on the antennal club. This localization corresponded to the distribution of the morphologically defined sensilla trichodea and basiconica (Mustaparta, 1973), indicating that the olfactory receptors innervate these sensory organs. The receptors of the morphologically different sensilla types were found to respond to different classes of substances (pheromone related compounds and various food odours, respectively). Within each type of olfactory organ the receptors could be further subdivided into two groups on the basis of the degree of specialization. Thus, one group of trichodeal receptors, T 1, were the most highly specialized. Each responded to only one compound of which some were bark beetle pheromones. As these compounds are likely to be related to the pheromones of the pine weevil, these trichodeal receptors are suggested to be pheromone receptors. Other trichodeal receptors, T 2, showed a broader response pattern, which included bark beetle pheromones as well as some food odours. These two groups of trichodeal receptors were found in different regions of the antennal club. The most highly specialized basiconic receptors, B 1, responded strongly to the three monoterpenes, α-pinene,β-pinene and camphene and had in some cases a weaker response to a few other compounds. This suggests a special significance of these monoterpenes as food attractants. The majority of the basiconic receptors, B2, however, responded to many different compounds including monoterpenes, benzene derivatives, and cyclic and aliphatic hydrocarbon derivatives.

Notes: Summary 1. Sound production of grasshoppers is based upon central motor patterns which are hierarchically organized at various functional levels (Fig. 2). These involve coordination (i) of single motor units belonging to the same muscles, (ii) of muscles relating to one hindleg, and (iii) of laterally homologous muscles moving the left and the right hindleg, respectively. 2. The motor organization at the first two levels has been investigated comparatively in several species. The neuromuscular activity underlying stridulation was recorded in freely moving animals using flexible wire electrodes (diameter 20–30 μm) which allowed the functional identification of individual motor units (Fig. 3). Up to 30 electrodes were chronically implanted into the metathoracic muscles without restricting the behaviour. 3. The motor patterns are based upon certain principles some of which are generally valid for all species: (i) The individual units are characterized by discrete types of activity (Fig. 4). (ii) Motor units and muscles are always recruited in a fixed order (Figs. 1, 3, 10). 4. The co-ordination of single units does not follow a general scheme but it reflects features of the specific song patterns (Fig. 5). The muscles producing the movements of one hindleg are also specifically co-ordinated: (i) In rapidly stridulating species the sets of antagonistic muscles are coupled in an unequivocal (unimodal) manner from which the pattern of leg movements can easily be deduced (Figs. 11, 12, 13). (ii) On the other hand, in slowly stridulating species the antagonistic muscles are coupled in two ways, since several of them are recruited both before the beginning and at the end of the leg strokes (Figs. 7–9). Maximum of motor activity is usually found at the end of the upward movements where the activities of both the elevator and depressor muscles partly overlap (Fig. 7b).

Notes: Summary 1. In free running bees turns through an arbitrary angle were elicited by switching the light sources, which attracted the insects. 2. During the swift forward run the bees used the alternating tripod gait. During the slow walk the period of stepping cycleT could be longer than the time of run of the metachronal wavet m .t m and, more seldom,T could be different on the right and left side. 3. The methods a bee used for turning can be ranged according to increasing effectivity as follows: a) alterations of step amplitude and direction of drag, the gait remaining unchanged; b) duration ofT andt m increased on the inner side of the animal and decreased on the outer side; c) the hind leg of the inner side halted; d) the same did the hind leg of the outer side; e) the legs of the inner side walked backwards. 4. As an estimate of turning efficiency we adopted the length of the path during turning, i.e. the trajectory of the centre of the thorax related to the turn for 1 radian. 5. With increasing the indicated angle of a turn from 0 to 180° the length of the path during the turn monotonously decreases, and in order to turn a bee applies more and more efficient modes. The conclusion is, that the turning command monotonously increases upon increasing of the error angle up to 180°. 6. This dependence of the turning command upon the error angle is compared to the well-known sinusoidal relationship, which was deduced from experiments in stationary (not transient) orientation.

Notes: Summary Partially blind mutants can be used to investigate the processing of visual information in the fruit flyDrosophila. This approach requires (1) procedures for the selection of a variety of partially blind mutants, and (2) a strategy for the identification and coordination of visual malfunctions by comparison of interrelated traits of behaviour. The two selection techniques so far employed to recover partially blind mutants use either the fast phototaxis or the optomotor response as selection determining behaviour. The second method is described here and is applied specifically to select mutants in which one of the two autonomous subsystems of vision designated asHigh Sensitivity System andHigh Acuity System is defective. (The mutants obtained are apparently normal with respect to their HAS whereas the HSS is blocked.) Two sets of experiments have been developed in order to test interrelated traits of behaviour in a comparatively large number of flies. One set of experiments measuresslow phototaxis as a function of light intensity. The other is to determine the optomotor response to moving patterns of different spatial periods as functions of both the average brightness and the speed of the movement. Further techniques such as electroretinography and optical inspection of the eyes are used to complement the behavioural approach. By combination of the different tests a first step has been made in the characterization and classification of partially blind mutants with neuronal disorders obtained by different selection procedures and in different laboratories.

Notes: Summary Beavers studied under natural conditions near Québec City, Canada, displayed a yearly cycle of patterns of activity rhythms. In winter, the beaver colonies had a free-running circadian rhythm of period length 26.25 to 28.0 h, with or without relative coordination, depending on available light intensity, which in turn depends on ice and snow cover conditions; in summer, their activity rhythm followed a “normal” 24 h period. Transitions between these two patterns suggest that annual variations in the beaver's physiological state affect their reaction towards the presence or absence of a Zeitgeber.

Notes: Summary The locomotor response of juvenileGinglymostoma cirratum, the nurse shark, to six covert, discrete sources of an attractant chemical stimulus (fresh shrimp extract) was monitored in a tank (5×5×0.5 m) by means of a square matrix of 1936 photocells embedded in the floor and an on line computer. The experiments were done in flowing (1.17 cm/s) and stagnant water in order to determine the effects of flow on the accuracy of localization and to clarify some of the locomotor mechanisms involved. The response was quantified by a temporal and spatial analysis of activity, distance travelled, mean velocity, mean turn size, step length between turns and its direction vector, frequency of turning, the time spent by the animal in the quadrants of the tank, the mean direction vector of the steps and computer plots of locomotor pathways. For controls, the locomotion was monitored in the absence of chemical stimulation and with a placebo (seawater) replacing the shrimp extract. Five animals were used in 22 experiments in flowing, 20 in stagnant water. The relationship between each of the above-mentioned locomotor variables and the position of the discrete source of stimulation was examined by regression analyses and compared quantitatively between flowing and stagnant water. Localization is very precise in flowing water and is dependent on the gradient of the stimulus in the medium. Downstream sites of stimulation are better localized than upstream ones. In stagnant water only generalized localization occurs. The flowing water provides the direction vector for precise localization.

Notes: Summary 1. The club-shaped hairs are innervated by one sensory cell with phasic-tonic properties. The largest changes of spike frequency are produced by deflection of the hairs along their preferential plane. The smallest deflection that will induce changes of the spike frequency is 0.1°. The height of the phasic response is correlated to the rising time of the stimulus. Sinusoidal stimuli up to 300 Hz cause stimulus-synchronized spike trains. 2. Spikes of the campaniform sensilla lying at the base of the club-shaped hairs were recorded simultaneously with the spikes of the hairs. The excitation pattern of the campaniform sensilla is phasic. They are excitated only by moving the cup of the club-shaped hairs, not by deflecting the hairs alone. 3. The cricket may determine its position in relation to the gravity field by means of the club-shaped hairs. This can be demonstrated indirectly by measuring the deflexion of the hairs in the gravity field and registration of the electro-physiological characteristics of the receptor. Direct evidence is obtained by recording the nerve spikes while turning the cricket in the gravity field.

Notes: Summary Conditioning experiments in cod ended in the results: 1. Cod discriminates travelling sound waves impinging on the head from those impinging on the tail at 75 Hz. 2. Phase reversal of the acoustic pressure in the travelling wave caused 180° reversal of the directional responses. 3. Directional hearing in the loop of a standing wave appeared possible provided that additionalp-information in the correct phase was added.

Notes: Summary Aims: Further investigation of the “component of throttling back” which functions as a short term inhibition of particular vocal outputs (song-phrases) of birds (Fig. 1).Methods: Blackbirds (Turdus merula) having a clearly organized singing behaviour and living under controlled conditions were exposed to “taped copies” of song phrases of their own repertoire. The experiments consisted of “echo-stimulations”, “continued stimulation” and of combinations of both of these (Fig. 2). Additionally the normal songs of the birds were recorded for control.Results: 1. Under continued stimulations with copies of a particular one of their phrases—here called output “A”—the birds uttered their own outputs A more often than in normal songs but almost as frequently as under echo stimulations with A. During the experiments the releasing effect of the stimuli did not decrease; in other words: there was no afferent adaptation to the stimuli. The echo stimulation with A raised the repetition rate of output A. (Effects of the input-component: Fig. 4.) 2. Auditory stimulations with pattern A changed the rate of output A occurring at the preferred recurrence intervals. However, they did not change the length of this preferred intervals. (Effects of the period component: Fig. 4.) 3. The increase in the repetition rates of output A did not exceed a certain limit (Fig. 3). In correlation with this increase two types of effects were observed: In comparison with normal songs there was first a sharp decline in the ratio of outputs A uttered within a sequential interval of 3 or 4 phrases (short term effect). After a sequential interval A→A of more than 4 phrases there followed a slow recovery (long term effect) of that ratio. The magnitude of both the decline and the recovery were proportional to the initially increased repetition (Fig. 5). These effects are explained by the “component of throttling back of outputs”: The values of the throttling component have to range between 0 and 1 and interact with the actual values of the other components multiplicatively. Every utterence of an output A results in a reduction of the value of the “throttling component” belonging to this output. The reduction declines “slowly” (Figs. 6, 7).

Notes: Summary The cod,Gadus morhua L., can hear the direction of a sound source of 75 Hz in the transversal plane. At the experimental site in the middle of a fjord, local depth 35 m, the sound sources were situated at radial distances of 4 to 5.3 m from the subject in its netting cage. Both in two-alternative and four alternative choice experiments, in which an acoustic discrimination of separate similar sound sources was required, reward conditioning yielded positive results. The bearing of the sound source was decisive for the discrimination and not the identity of the sound sources used (intensity or timbre deviations). If the reverberation characteristics of the fjord at the receiving point were strongly dependent on the spatial position of the source, the results of the choice experiments might represent a demonstration of pseudo-directional hearing. However, from acoustic measurements of the time averages of the sound parameters such an anisotropy for sources with different bearing was not apparent (Fig. 5). Furthermore, in a well-trained cod, in which the pars inferior of only one single labyrinth was put out of function by surgery, the discrimination of the bearing of the sound sources was abolished but not the detection of sound as such (see Table 5). Detection of the direction of the sound therefore seems to be a function of the labyrinths and not of the lateral line system (directionalhearing). Estimates are given of the minimal angle that can be distinguished (about 22° for a 50% detectability likelihood; Fig. 6), and of the minimal acoustic level necessary for acoustic orientation (about — 13 dB re 1 μ bar; see Fig. 9). Finally an extension to an existing detection model of directional hearing is proposed. It receives empirical support in the next paper (Schuijf and Buwalda, 1975).

Notes: Summary An intense blue light stimulus induces a prolonged depolarizing after-potential (PDA) in the peripheral retinula cells, but not in the central retinula cells, of theDrosophila ommatidia, providing the fly has been dark or red adapted and the screening pigments have been genetically removed from the compound eye. Thus, the PDA saturates only the peripheral retinula cells, allowing one to isolate and study extracellularly the summed receptor potentials (SR) of the central retinula cells (Fig. 1). The following lines of evidence support these ideas: a) The on and off transients, typical of the normal electroretinogram (ERG), are not present in the SR (Fig. 1). b) The intensity response curve of the intracellularly recorded responses of the peripheral retinula cells fits that of the ERG only after subtraction of the SR contribution from the latter (Fig. 2). c) The SR action spectrum is different from that of the dark adapted ERG and appears to arise from more than one spectral mechanism (Fig. 3).

Notes: Summary The daily rhythm in an enzyme, pineal serotonin N-acetyltransferase activity was studied in chickens kept in conditions of constant dark. The rhythm persisted and had a period length of approximately 24 hours which are characteristics of truly circadian rhythms. The detailed documentation of the rhythm (Fig. 1) shows the shape of the oscillation and clear anticipation of the time of lights on. Both the rise and fall of the rhythm occur without stimulation by light or dark.

Notes: Summary Testicular weight and spermatogenic activity in the green anole,Anolis carolinensis, is maintained under long (14 hr) photoperiods in the summer in both sighted and blinded lizards whereas short days (6 hr) cause testicular regression. In the fall, long photoperiods cause testicular recrudescence and maturation in blinded and blinded-parietalectomized anoles as well as in sighted anoles. In all cases the spermatogenic activity of the testes was similar in blind and sighted anoles but some significant differences between the testis weights of blind and sighted anoles in the fall were noted. This is the first demonstration that extraretinal photoreceptors can mediate gonadal responses to light in reptiles.

Notes: Summary 1. The visually guided flight behaviour of groups of male and femaleSyritta pipiens was filmed at 50 f.p.s. and analysed frame by frame. Sometimes the flies cruise around ignoring each other. At other times males but not females track other flies closely, during which the body axis points accurately towards the leading fly. 2. The eyes of males but not females have a forward directed region of enlarged facets where the resolution is 2 to 3 times greater than elsewhere. The inter-ommatidial angle in this “fovea” is 0.6°. 3. Targets outside the fovea are fixated by accurately directed, intermittent, open-loop body saccades. Fixation of moving targets within the fovea is maintained by “continuous” tracking in which the angular position of the target on the retina (Θ e) is continuously translated into the angular velocity of the tracking fly ( $$\dot \Phi _p $$ ) with a latency of roughly 20 ms ( $$\dot \Phi _p = k \Theta _e $$ , wherek≏30 s−1). 4. The tracking fly maintains a roughly constant distance (in the range 5–15 cm) from the target. If the distance between the two flies is more than some set value the fly moves forwards, if it is less the fly moves backwards. The forward or backward velocity ( $$\dot F_p $$ ) increases with the difference (D-D 0) between the actual and desired distance ( $$\dot F_p = k^\prime (D - D_0 )$$ ), wherek′=10 to 20 s−1). It is argued that the fly computes distance by measuring the vertical substense of the target image on the retina. 5. Angular tracking is sometimes, at the tracking fly's choice,supplemented by changes in sideways velocity. The fly predicts a suitable sideways velocity probably on the basis of a running averageΘ e , but not its instantaneous value. Alternatively, when the target is almost stationary, angular tracking may bereplaced by sideways tracking. In this case the sideways velocity ( $$\dot S$$ ) is related toΘ e about 30 ms earlier ( $$\dot S_p = k\prime \prime \Theta _e $$ , wherek″=2.5 cm · s−1 · deg−1), and the angular tracking system is inoperative. 6. When the leading fly settles the tracking fly often moves rapidly sideways in an arc centred on the leading fly. During thesevoluntary sideways movements the male continues to point his head at the target. He does this not by correctingΘ e , which is usually zero, but by predicting the angular velocity needed to maintain fixation. This prediction requires knowledge of both the distance between the flies and the tracking fly's sideways velocity. It is shown that the fly tends to over-estimate distance by about 20%. 7. When two males meet head on during tracking the pursuit may be cut short as a result of vigorous sideways oscillations of both flies. These side-to-side movements are synchronised so that the males move in opposite directions, and the oscillations usually grow in size until the males separate. The angular tracking system is active during “wobbling” and it is shown that to synchronise the two flies the sideways tracking system must also be operative. The combined action of both systems in the two flies leads to instability and so provides a simple way of automatically separating two males. 8. Tracking is probably sexual in function and often culminates in a rapid dart towards the leading fly, after the latter has settled. During these “rapes” the male accelerates continuously at about 500 cm · s−2, turning just before it lands so that it is in the copulatory position. The male rapes flies of either sex indicating that successful copulation involves more trial and error than recognition. 9. During cruising flight the angular velocity of the fly is zero except for brief saccadic turns. There is often a sideways component to flight which means that the body axis is not necessarily in the direction of flight. Changes in flight direction are made either by means of saccades or by adjusting the ratio of sideways to forward velocity ( $$\dot S/\dot F$$ ). Changes in body axis are frequently made without any change in the direction of flight. On these occasions, when the fly makes an angular saccade, it simultaneously adjusts $$\dot S/\dot F$$ by an appropriate amount. 10. Flies change course when they approach flowers using the same variety of mechanisms: a series of saccades, adjustments to $$\dot S/\dot F$$ , or by a mixture of the two. 11. The optomotor response, which tends to prevent rotation except during saccades, is active both during cruising and tracking flight.

Notes: Summary 1. Caterpillars of the cabbage mothBarathra brassicae react to low frequency sound stimuli with defensive reactions (stopping, squirming, dropping). 2. In the sound field of a standing wave in a Kundt's tube the caterpillars do not react at places of maximal sound pressure, but only where sound-produced air motion is maximal. It is shown in controls that these reactions are not released by vibration of the supporting platform. 3. The threshold curve of sensitivity to sound is measured in the Kundt's tube for 300 Hz ≦f≦1 000 Hz and in a different setup for lower frequencies. Caterpillars react to sound between 40≦f≦1 000 Hz; threshold is lowest at 100 Hz≦f≦ 600 Hz, where a constant displacement amplitude of 1.5 to 2·10−4cm is sufficient to release defensive reactions to sound. Displacement is therefore regarded to be the effective stimulus parameter. 4. 8 filiform hairs standing dorso-laterally on the thoracal segments are responsible for sound sensitivity. Their length is 508∓26 μm, their basal width 5∓1 μm; each of them is innervated by a single receptor cell. Sound reception thresholds are normal as long as 4 of these hairs are intact; with 2 intact hairs, the threshold is increased threefold and with only 1, sixfold. 5. The conditions of sound—or rather medium vibration—reception in the far-field and in the near-field of sound sources are discussed with reference to possible natural sources of vibrational stimulation for the caterpillars.

Notes: Summary Integrated taste responses to chemical stimulation of the tongue were recorded from the intact chorda tympani nerve in four species of gerbils (Meriones libycus, M. shawi, M. unguiculatus andPsammomys obesus). 1. Sucrose was one of the most effective stimulants. 2. In comparison with sucrose, NaCl was less effective in gerbils than in other rodents. The smallest NaCl responses were found in those gerbil species whose native habitat and food subject them to the greatest osmotic stress. 3. The non-linearity of the NaCl concentration-response data suggested there may be more than one type of NaCl receptor site. 4. Two groups of cations were recognized as stimulants inMeriones species: (Na+, Li+) and (K+, Rb+, Cs+). 5. The stimulating effectiveness of methylα andβ-D-glucopyranoside was compared with several naturally occuring sugars. From this analysis, it was concluded that the stimulating potency of glucopyranoside is increased by an alpha linked substituent, as in sucrose. 6. The only reliable neural responses to water rinse occured with the divalent cations in the two species not found in extreme desert. It is improbable that gustatory water responses play a role in the water balance of desert rodents. 7. Sunflower seeds contain 4.28% sucrose which is the dominant sapid substance. Lipid soluble chemicals did not stimulate the taste receptors. 8. Some aspects of the evolution of gustatory systems are discussed.

Notes: Summary 1. The electric fields of four species of wave type, gymnotid fishes were measured and mapped using a technique that allowed accurate assessment of small electric fields, free of unknown field compression and distortion artifacts. 2. Dipole moment values were calculated for each fish's electric field from measurements made at a sufficient distance (Table 1). A dipole moment is an absolute evaluation of the electric fish's field strength that can be used for quantitative, intraspecific and interspecific comparisons. 3. The electric fish, as a field source, represents a distributed rostral pole and a point-like caudal pole (Fig. 2). Deviations of a fish's electric field from that of a dipole field increase with fish size, decreasing water resistivity, and decreasing distance from the fish. 4. Apteronotid species maintain a constant current electric organ output (dropping less than 5%) in water of resistivity up to 15 kOhm · cm, whereas rhamphichthyid species maintain a constant current output only in water up to 10 kOhm · cm (Fig. 6). Within each family, the larger fish maintained their current output level in higher water resistivities than did smaller fish. 5. Electrocommunication distances for the individual fishes are predicted based upon their measured electric field magnitudes and the known electrosensitivities of these species (Table 2); consequences of the geometry of the fishes' electric fields on object detection and object resolution are discussed.

Notes: Summary The influence of crowding in different group sizes on the metabolism of noradrenaline (NE) in six different brain areas and on some peripheral data in male and female mice was investigated. In the basal ganglia, the diencephalon and the mesencephalon-pons region, the NE turnover decreases from animals housed singly to groups of 16 animals per cage and then increases again (Figs. 1, 2, 3). In the cortex and in the cerebellum no changes of the NE metabolism with group size took place. Of all parameters investigated, only the corticoid levels in the plasma after exposure to a new environment correlated individually with the density-induced changes of the NE metabolism in the basal ganglia (Fig. 6a, b). The effects of acute and chronic stress on the NE metabolism and on amphetamine toxicity were discussed.

Notes: Summary The influence of crowding in different group sizes on the metabolism of serotonin (5-HT) in six different brain areas and on some peripheral data in male and female mice was investigated. In the cortex, the diencephalon and in the basal ganglia, the 5-HT turnover of male mice increases with group size. The females react differently (Figs. 2, 3, 4). The densityinduced changes in the 5-HT metabolism of the mesencephalon correlated individually with the locomotor reactivity of the animals in an open-field (Figs. 8, 9). The septal area is the only part of the brain in male and female mice in which the 5-HT turnover increase depends on group size (Fig. 5).

Notes: Summary 1. The morphology and function of the photoexcitable neurones located within the central nervous system (CNS) of the marine pulmonate mollusc,Onchidium verruculatum were investigated. 2. Intracellular cobalt injection visualized the geometry of axonal branches of the photoexcitable neurones, Ep-2, Ep-3 and Es-1. Ep-2 in the right pleuro-parietal ganglion sends its branches into right and left pleuro-parietal nerves, right pedal nerves and abdominal nerve 1. The branches in the right pleuro-parietal nerves were larger than those in the left pleuro-parietal nerve, the right pedal nerves and the abdominal nerve 1. The branching pattern of Ep-3 in the left pleuro-parietal ganglion was almost the mirror image of that of Ep-2. Es-1 in the abdominal ganglion sends its branches of equal sizes into the left and right pleuro-parietal nerves and the abdominal nerve 1. 3. The axon pathways described above were confirmed by electrophysiological analyses. It was also suggested that the impulses initiated in the smaller branches of Ep-2 and Ep-3 did not invade into the larger branches. 4. The interaction among the synaptic inputs to Ep-2, Ep-3 and Es-1 from various nerves converging to the ganglion complex was investigated by simultaneous intracellular recordings in any two of three neurones following orthodromic stimulation. The presence of the common input to Ep-2 and Ep-3 was also shown by simultaneous recordings.

Notes: Summary 1) Auxiliary optical marks placed at the food goal serve as rank- and racespecific learning criteria and influence the orientation performance of theApis mellifera carnica andApis mellifera ligustica. 2) The bees are not conditioned race-specifically by optical marks placed at a longer distance from the food goal. The visual structure of the more distant surroundings and the absolute distance of the food goal determine the rise, gradient, and level of such learning curves. 3) When orientation cues from optical marks and the sun compass are lacking, both races are incapable of optically determining the exact position of the food goal (tests in a circular arena under totally overcast skies). 4) When there are no optical marks near the goal, polarization substitutes adequately for the sun compass. 5) When an artificial optical mark is removed from a formerly learned, complex set of marks, relearning is prohibited by pro-active processes during a particular latency phase. During this latency phase the stored information is forgotten; however, the first learning step is excluded from any forgetting process. Relearning an easier task, with the addition of an optical mark to the former set of marks, takes place without difficulty.

Notes: Summary From fledging time up to the test releases, two groups of experimental pigeons were housed in two cubic cages supplied with deflectors which deviated the winds through to the inside approximately 70° clockwise (CW-birds) or counter-clockwise (CCW-birds). Test releases were made at 9.0, 23.5, and 105.3 km from the loft. With respect to that of control birds, the mean bearing of CW-birds was always deflected clockwise, and that of CCW-birds was always deflected counter-clockwise. Control birds performed better than CW-birds in homing from the first release site, and better than both experimental groups from the second release site. These results agree with the olfactory hypothesis of pigeon navigation (Papiet al., 1972).

Notes: Summary 1. The physiological effects of two inhibitory axons supplying the stretcher muscles of three crabs (Hyas, Gecarcinus andGrapsus) were investigated, with a view to establishing the relative importance of pre- and postsynaptic inhibition. 2. InHyas, the specific inhibitory (SI) axon and the common inhibitory (CI) axon both exerted powerful presynaptic inhibition on the terminals of the excitatory axon. The effect of the SI axon was generally stronger, but some excitatory terminals were found in which CI axon stimulation was more effective. Thus, inhibition of the excitatory postsynaptic potential recorded intracellularly from the muscle fiber is the statistical result of variable inhibition at different excitatory terminals. 3. InHyas, postsynaptic inhibition was insignificant at low frequencies of stimulation, but increased at higher frequencies, for both SI and CI axons. The SI axon had a stronger postsynaptic effect than the CI axon. 4. InGecarcinus, the CI axon had a more powerful postsynaptic effect than the SI axon, whereas the SI axon was more effective at the presynaptic level. The two axons are specialized for different types of inhibition. 5. InGrapsus, the SI axon was more effective than the CI axon at both pre- and postsynaptic levels. Thus, considerable variation in pre- and postsynaptic connections of the two inhibitor axons occurs in different species of crabs. 6. In all species, the CI axon was least effective in muscle fibers with small, facilitating excitatory postsynaptic potentials. Sometimes the CI axon did not produce any effect at all in such fibers. 7. Presynaptic inhibition in crabs probably occurs mainly at narrow “bottlenecks” of the excitatory axon, where impulses are easily blocked by inhibitory synaptic action.

Notes: Summary 1. The choice reaction of freely flying honey bees which are trained to a spectral colour and tested against an alternative colour is time dependent. Between 3 and 15 min after the reward the percentage of correct choices increases and reaches a steady state. This process is called consolidation. 2. Immediately after single short rewards (2, 5, 10 or 20 sec) the percentage of correct choices is as high as after 15 min of consolidation. The reaction decreases within 2 min and reaches a minimum. The time course of the percentage of correct choices in the honey bee after a single reward is bi-phasic. 3. In the first 4 min after a single reward the choice reaction is negatively correlated with the duration of reward. Short (2 sec) rewards lead to a higher percentage of correct choices than long (10 or 20 sec) rewards. 4. Rewards that last 100 msec or more act as a reinforcement in bees. The phasic response of the taste receptors is sufficient to associate a colour with sugar water. The optimum duration of reward after a single trial is about 1 sec. 5. The memory of the bee after a reward can be impaired by different treatments (electro-convulsive shock, CO2- or N2-narcosis and cooling). The degree of susceptibility to impairment and the time dependence of the choice reaction until 2 min after the reward are correlated. It is discussed that short-term memory formation in the honey bee is based on different physiological mechanisms which work together.

Notes: Summary In his discussion of the optomotor behaviour Kalmus claimed in 1964 that the visual systems of insects continuously resolve horizontal displacements relative to the surroundings into rotatory and translatory components, each associated with optomotor feedback of particular quality and sign. The feedback is supposed to achieve, simultaneously, minimization of the rotatory movements and maximization of the translatory movements, a behaviour repeatedly observed with actively moving insects such as the fruitflyDrosophila melanogaster. The present approach takes into account that the output of movement detectors in the visual system of insects is necessarily equivocal with respect to the speed of the stimulus (e.g. zero output at both zero and infinite speed). Decomposition of the stimulus is not feasible under these conditions. It is obviously the composite stimulus to which the insects respond. Moreover, there is experimental evidence that optomotor feedback on the translatory movement is not necessarily a response-determining factor in insects. The optomotor behaviour of the walking fruitfly is sufficiently described by the sum of itsrotatory responses to the composite stimuli on either side. A diagram representing the expected rotatory response of the walking fruitfly as a function of both the rotatory and the translatory stimulus component is used to derive the prevailing traits of the behaviour in resting, rotating and floating environments, respectively. Most conspicuous is the inversion of the course-control response in about one half of the possible states of stimulation. This effect gives rise to at least some of the apparently spontaneous turns of actively moving insects which have been ascribed by v. Holst and Mittelstaedt to efferent commands from higher centres of the brain, according to their principle of reafference. The present results merely disprove the necessity of these commands. Inversion of the response is also an inherent property of the course-control systems of the optomotorically active insects. The expected increase of these inversions with closer proximity of the visual environment is found by observation of walking fruitflies. The relation between the rotatory and translatory movements of the freely walking fly and its state of stimulation in a given environment is used to describe the expected behaviour in terms of the most probable transition of state. The approach is based on estimates of the power required by the fly in order to maintain a given state against the torque that is produced by its course-control system in response to the optomotor stimulation. The most probable transition of state is apparently determined by the tendency of the fly to decrease the power requirement by appropriate adaptation of its rotatory movement. The transition may come to an end in one of the states of minimum power requirement where the speed of the rotating fly is held in a stable optomotor equilibrium.

Notes: Summary 1) Interruptions of sucking while the bee is sitting on the disc with the learning colour lead to low susceptibility to impairment after external treatments (ECS, CO2- or N2-narcosis and cooling). Repeated short rewards with landing on the learning colour qualitatively give the same result. Only part of the information stored is susceptible to impairment in these experiments. 2) With electroconvulsive shocks (ECS), CO2-narcosis and cooling the frequency of correct choices after a single reward can be set to stable values. The frequency of correct choices after more rewards depends on this initially set choice reaction. 3) A linear learning model can be used to describe the dependence of the choice reactions before and after a reward. A relative measure of the input information to the learning system can be gained from this model. This measure is called “relative learning step”. 4) The calculation of the “relative learning steps” for the experiments with different rewards shows that the transfer rate of information from short to long-term memory in the bee is constant for different reward situations. 5) The subjective input to the learning system increases linearly with the number of sucking interruptions. 6) The dynamics of learning in the honey bee can be described in a model with three different types of storages: Two short-term storages, which are characterized by the susceptibility to impairment and the consolidation function and a long-term storage. Depending on the reward situation the signal progression can be serial and parallel.

Notes: Summary Extracts of the taste hair rich tarsi of the pro- and mesothoracic legs of the flyProtophormia terraenovae contain five chromatographically separable α-glucosidases (E.C. 3.2.1.20). These glucosidases were characterized according to their substrate specificities, their Michaelis constants and their pH optima. The enzymes GLU I, III and V show a broad specificity for several α-glucosides (sucrose, maltose, turanose, palatinose, melezitose and p-nitrophenyl-α-glucoside). The GLU II and IV split sucrose especially with extraordinarily high Michaelis constants (0.1–0.2 M). The properties of the fly enzymes were compared with those of other origine (intestine of mammals, yeast), but especially with those of the fly's taste hair rich labella (Morita and coworkers, 1972–1974). The enzyme GLU III exhibits properties indicating that it may be the sugar receptor protein in question.

Notes: Abstract TheIf-1 alleles of many inbred strains, some of common parentage with either BALB/c Gif or C57BL/Lac, were determined. Of the 23 inbred lines examined, all were eitherIf-1 h orIf-1 l , except the C57BR/cdJ strain, which gave intermediate results; the latter will have to be explored more thoroughly before the existence of a third allele can be established. Survey of the 23 lines showed no correlation betweenH-2 haplotypes andIf-1 alleles. The absence of linkage betweenH-2 andIf-1 was confirmed by typing (BALB/c×C57BL)F1×C57BL backcross progeny for bothH-2 andIf-1. The fact that some high and some low producers were of sameH-2 type made it possible to study the production of interferon in radiation chimeras. Mice of a low-producer strain, C3H/Lac (If-1 l , were lethally irradiated and their hemopoietic function restored by grafting bone marrow from eitherIf-1 l orIf-1 h mice, all donors of the sameH-2 haplotype as that of the recipients (H-2 k . NDV-induced serum interferon production was measured 31 days after irradiation and restoration. The production of interferon in all mice restored with marrow fromIf-1 l donors was equal or lower than that of syngeneic chimeras (alsoIf-1 l ). In contrast, titers of interferon in all four groups restored withIf-1 h marrow were higher than those of control chimeras, three being higher than titers in unirradiatedIf-1 l controls. These data indicate that theIf-1 locus is expressed through cells derived from hemopoietic stem cells, possibly the interferon-producing cells themselves.

Notes: Abstract Chimeras were induced in doves (Streptopelia) by making parabionts of embryonating eggs that carried genes for erythrocyte antigens, which were readily identified. The parabiotic pairs were chosen so that new antigenic specificities would appear if somatic cell mating took place. However, no evidence of somatic cell mating was noted. Erythrocytic chimerism was no longer. detectable in some birds after varying periods of time. In a few others tolerance was presumably lost, since their plasma contained antibodies against cellular antigens that either were present, or had been present, in the bird's circulation.

Notes: Abstract The primary anti-NP response in C57BL/6 and CBA mice was analyzed by isoelectric focusing. Antibody responses in C57 mice were restricted in heterogeneity and over 80 % of this strain shared an isoelectric focusing spectrum characteristic of an homogeneous antibody (spectrotype). This spectrotype N-l was inherited as a dominant characteristic in (CBA×C57)F1 mice, and backcross analysis revealed that it was genetically linked to the heavy chain allotypeIg-1 b . It thus behaved as a marker similar to the fine specificity characteristic of heteroclitic antibody. Elution studies showed that antibody with the spectrotype N-1 was heteroclitic, with a higher affinity for NIP and NNP than for the immunogen NP. It is argued that a) a single germ-lineV gene (designated N-1) codes for the VH region of this antibody and b) in C57BL/6 mice this geneV H N-1 is closely linked toIg-1 b .

Notes: Abstract Surfaces of cultured human lymphoid cells RPMI 1788, RPMI 4098, RPMI 8866, Raji, and WI-L2 were found to contain bothβ 2-microglobulin (β 2-μ) and HL-A determinants when tested by direct complement-dependent cytotoxicity andquantitative absorption with different cytotoxic antiβ 2-μ antisera and specific HL-A alloantisera. The same antigenic specificities were found in 3M KCl extracts of these cultured cells with a sensitiveβ 2-μ radioimmunoassay and an HL-A antigen blocking assay. Daudi cells provided a contrast, since noβ 2-μ or HL-A determinants were found on their surfaces or in 3 M KCl extracts prepared from them. Results from specific antibody blocking tests suggest a close association betweenβ 2-μ and HL-A determinants on plasma membranes of cultured human lymphoid cells. A solid state immunoadsorbent containing antiβ 2-μ antibodies effectively removed all detectable HL-A antigenic activity from some 3M KCl extracts of cultured human lymphoid cells as well as from some sera. Adsorption of HL-A antigens to these immunoadsorbents was specific since it was blocked only by prior addition ofβ 2-μ. Once on the antiβ 2-μ immunoadsorbents, HL-A antigens still reacted specifically with HL-A alloantibodies in quantitative absorption experiments. HL-A antigens andβ 2-μ could be eluted from antiβ 2-μ immunoadsorbents with a variety of chaotropic reagents and detergents, but thus far potassium bromide and sodium dodecyl sulfate (SDS) appear to be the most effective. SDS-PAGE of these eluates indicated that HL-A antigens were considerably purified by adsorption to antiβ 2-μ immunoadsorbents and that two major molecular size fragments were distinguishable, i.e., ∼33,000 for HL-A and ∼ 12,000 forβ 2-μ.

Notes: Abstract The response potential of inbred mouse strains against bovine type I procollagen and its separated structural domains, i.e., the globular procollagen peptide and the triple-helical collagen moiety, was compared by passive hemagglutination and radioimmune assays. Studies with congenic and recombinant lines and with backcross populations showed that the antibody response to procollagen peptide is under the control of a gene located in theIA, IB subregion of theH-2 complex. The strain distribution pattern of high response to the procollagen peptide is not identical to that of the high response to collagen. Both the procollagen peptide and procollagen are thymus-dependent antigens, since no response was observed in nude mice. Low response to procollagen peptide and/or collagen could be corrected in some, but not all mouse strains by using procollagen as immunogen. Strains which show low response against collagen but high response against procollagen were injected with collagen prior to a challenge with procollagen. This treatment reduced the antibody response to the procollagen peptide but not to collagen. Carrier and suppressor effects in the response to procollagen are apparently more complex than those observed in the response to synthetic peptides.

Notes: Abstract In the present work, we used the differential redistribution method to study the molecular expression of several H-2 specificities controlled by theD region of theH-2 a haplotype. We observed that: capping of the private specificity H-2.4 induced capping of the public specificities H-2.3, H-2.35, and H-2.36, and vice versa; capping of any one of these specificities did not induce capping of the public specificity H-2.28, controlled by the same region. By contrast, capping of the H-2.28 specificity induced capping of these specificities; redistribution of H-2K and H-2D private specificities or redistribution of H-2D private specificity and Ia specificities did not induce capping of the H-2.28 specificity. These data indicate that a part of a molecule carrying the H-2.28 specificity is linked to a molecule carrying H-2.4, H-2.3, H-2.35, and H-2.36 specificities and that a part of a polypeptide chain bearing the H-2.28 specificity is independent from that bearing other specificities controlled either by theD region (i.e., H-2.4, H-2.3, H-2.35, and H-2.36) or by theK andI regions. These results further strengthened the hypothesis of the existence of at least two genes controlling theD-region H-2 antigenic specificities.

Notes: Abstract A newH-2 mutant, BALB/c-H-2 db , is described. This mutant originated in BALB/c, is inbred, and is coisogenic with the parental BALB/cKh strain. The mutation is of the loss type since BALB/c-H- db rejects BALB/c, but not vice versa. Complementation studies have localized the mutation to theD region of theH-2 complex. A cross between BALB/c-H-2 db and B10.D2-H-2 da failed to complement for either BALB/c or B10.D2 skin grafts, indicating that these are two separate mutations at the same locus (Z2). Direct serological analysis and absorption studies revealed that, with one exception, theH-2 andIa specificities of BALB/c and BALB/c-H-2 db are identical. In particular,H-2.4, the H-2Dd private specificity, is quantitatively and qualitatively identical in the two strains. The exception is that of the specificities detected by antiserum D28b: (k×r)F1 anti-h, which contains anti-H-2.27, 28, and 29. These specificities appear to be absent from theH-2 db mutant since they are not detected directly or by absorption. Other public specificities are present in normal amounts,e.g., the reaction with antisera to H-2.3, 8, 13, 35, and 36. The reaction with antiserum D28 (f×k)F1 anti-s, which contains antibodies to H-2.28, 36, and 42, is the same in both strains. Antiserum made between the two strains (H-2 db anti-H-2 d ) reacts like an anti-H-2 serum, in that it reacts with both T and B cells by cytotoxicity, but is not a hemagglutinating antibody. The serum reacts as does the D28b serum in both strain distribution and in cross-absorption studies. We conclude that theH-2 db mutation occurred at a locus in theD region, resulting in the loss of the H-2.28 public serological specificity and of a histocompatibility antigen. Whether these are one and the same antigen is not yet known. The data, in view of other evidence, imply that the public and private specificities are coded for by separate genes.

Notes: Abstract The H-Y antigen has been studied under a variety of experimental conditions in BN and Lewis rats. The results indicate that 1. graft size is crucially important in determining the fate of male skin isografts on females; 2. H-Y incompatible ear skin grafts survive significantly better than those of trunk origin; 3. prior exposure of females to male lymphoid cells greatly increases their capacity to reject male skin isografts; 4. neonatal castration has no influence on the expression of H-Y; 5. multiparity can induce unresponsiveness to H-Y; and 6. although BN females respond better than do Lewis females to H-Y, the antigen is stronger in Lewis males. These findings are compared with the results of similar experiments conducted with mice.

Notes: Abstract Four cell lines derived from four-day-old SWR/J♀×SJL/J♂ mouse blastocysts have been assayed for their expression of H-2 specificities with pauci- and monospecific H-2 typing sera. Direct microcytotoxicity and indirect absorption studies reveal many deviations from expected expression of particular H-2 specificities based on the cell lines' genotypes and onH-2 typing of adult F1 lymphocytes. No pattern of selective expression of public or private specificities ofD-end orK- end specificities or of inclusion groups was noted. At least one public or private specificity of eachD q ,K q ,D s , andK s region is present, indicating that part of each product is expressed. The partial expression of H-2 specificities is discussed structurally, in terms of how incomplete H-2 molecules may be present on the cell surface, and developmentally, in terms of how the variant H-2 specificities may be involved in cell positioning during ontogenesis.

Notes: Abstract The primary humoral responses of mice to the linear random terpolymerl-Glu56-l-Lys35-l-Phe9 (GLø) were studied, utilizing the Farr antigen-binding technique and a new hemagglutination assay. This new hemagglutinin assay was easier and more convenient than the conventional Farr method, and was more sensitive in detecting early IgM responses. Following primary immunization, the majority of antibodies produced by responder strains were 2-ME-sensitive. These 2-ME-sensitive antibodies chromatographed at the same relative position as IgM on a Sepharose 6B column. On the other hand, no antibodies of either the IgM or IgG class could be detected in nonresponder strains. These data are consistent with the hypothesis that two complementingIr genes are required for the primary IgM response to GLø, in contrast to findings previously reported for (T,G)-A — L, anotherH-2-linked, complementing,Ir gene system. The implications of these differences are discussed.

Notes: Abstract Spleen cells carrying theH-2K b allele and sensitized against TNP-modified stimulator cells in vitro displayed a cytotoxic effect against TNP-modified target cells carrying a mutation in theH-2K b allele (haplotypesH-2 ba ,H-2 bd , andH-2 bf ). Similar crossreactivity in TNP-CML was observed in the reciprocal direction. Spleen cells carrying theH-2K k allele and sensitized against TNP-modified stimulators displayed a cytotoxic effect against TNP-modified target cells carrying a mutation in theH-2K k allele (haplotypeH-2 ka ) and vice versa. The effector cells in these assays were sensitive to anti-T cell serum in the presence of complement, and supernatants from immune cultures did not induce nonimmune cells to display a cytotoxic effect. Titration of effector cells from mutant and wild-type strains of theH-2 b haplotype indicated no detectable quantitative differences in their activities. These data demonstrate that crossreactivity in TNP-CML occurs in closely related allogeneic strains that have recently undergone mutation in theH-2 complex.

Notes: Abstract The mixed hemadsorption hybrid antibody (MHA.HA) test was applied successfully to the detection of antigens on the surface of testicular cells separated into sub-populations by velocity sedimentation at unit gravity in the “staput” apparatus. Normal serum from mice of all strains tested, both male and female, was found to contain a natural autoantibody that reacts with testicular cells of all mice tested, but not with sperm or other cells. This autoantibody is detectable at an age of 4–6 weeks in females, and reaches a plateau at about 10 weeks of age. The corresponding antigen is denoted TCDA, because it is evidently a Testicular Cell Differentiation Antigen. Microscopy of the cells forming rosettes in the MHA.HA test confirmed that the TCDA+ cells belong to the gametogenetic series. Because females as well as males produce the autoantibody we presume that TCDA is also present on female gametic cells although it was not feasible to test this adequately. The anti-TCDA autoantibody is not related to the natural autoantibody against sperm, which according to MHA.HA test occurs in the serum of males but not of virgin females.

Notes: Abstract The genetic control of the immune response to H-4 histocompatibility alloantigens is described. The rejection of H-4.2-incompatible skin grafts is regulated by anH-2-linkedIr gene. Fast responsiveness is determined by a dominant allele at theIrH-4.2 locus. TheH-2 b ,H-2 d , andH-2 s haplotypes share the fast response allele;H-2 a has the slow response allele. Through the use of intra-H-2 recombinants, we have mapped theIrH-4.2 locus to theI-B subregion of theH-2 complex; theH-2 h4 ,H-2 15, andH-2 t4 haplotypes are fast responder haplotypes. These observations suggest that the strength of non-H-2 histocompatibility antigens is ultimately determined by the antigen-specific recipient responsiveness.

Notes: Abstract By testing a family in which one offspring had inherited a chromosome including a recombination between theHLA-B andD loci, we sought to obtain some insight into whether determinants other than those atHLA-D are capable of restimulating in a secondary MLC. Results obtained in the primary MLC indicated that the recombinant child did not express products of theHLA-D region normally associated with this haplotype. When sensitization in a primary MLC was to the entire haplotype, everyone who had the sensitizing haplotype restimulated strongly and specifically. In addition, however, weak to moderate stimulation was obtained when the cells of the recombinant child were used to restimulate. Presumably these cells possessed determinants coded for within theHLA-A toB chromosomal segments of the sensitizing haplotype, but not those coded for by theHLA-D locus. Our results indicate that a simple structure atHLA-D is not the sole factor in the secondary MLC. Either the products of loci outside theHLA-D locus can also restimulate or the recombination occurred within theD locus, suggesting that theD region contains more than one locus coding for restimulating determinants.

Notes: Abstract The differential redistribution method was used to analyze the relationships between the antigens of the H-2.1 and H-2.28 families and the K- and D-region H-2 specificities on the lymphocyte surface. The experiments were performed on T peripheral lymphocytes of B10. AKM mice (H- 2m), where the H-2.28 specificity is controlled by theD region; C3H.OL mice (H- 20l), where the H-2.28 specificity is controlled by theK region and the H-2.1 specificity by theD region; and B10.A mice (H- 2a) where the H-2.1 specificity is controlled by theK region. The results show the following: 1. In the D-region products, the redistribution of the private specificities fails to induce the redistribution of the H-2.1 or H-2.28 specificity. Antibodies against the H-2.1 or H-2.28 specificity provoke the redistribution of the D-region private specificities. 2. In the K-region products, the H-2.1 or H-2.28 specificity cocaps with the private specificities. 3. In both K- and D-region products, the public specificity H-2.5 always cocapped by antibodies against the private specificity. These data suggest that the D-region H-2.1 specificity is, like the H-2.28 specificity, controlled by gene(s) different from theH- 2.D gene for the private, and most of the public, specificities. However, in the K-region products, the H-2.1 or H-2.28 specificity and the private specificities are either controlled by the same gene or expressed on two different molecules associated on the cell surface. These results provide evidence for the existence of two separate loci in theD region: the classicalH-2D locus, controlling the expression of the private specificity and most of the public specificity, and theH-2L locus, controlling the expression of the H-2.1 or H-2.28 specificity.

Notes: Abstract Mice were immunized intravenously with 4 × 107 thymocytes from Thy-1 disparate, eitherH-2-compatible orH- 2-incompatible donors. The magnitude of the anti-Thy-1.1 response was measured by determining the number of PFC in spleens of animals 6 days after immunization. Regardless of the origin of immunizing and target thymocytes, the assay employed detected exclusively PFC-producing antibodies to the Thy-1.1 antigen. In almost all instances,H-2-compatible thymocytes elicited a significantly higher response than didH-2-incompatible thymocytes, although the latter occasionally evoked a high response. TheH-2 incompatibility between donor and recipient appeared to be responsible for the differences in responsiveness of the standard inbred mice and theirH-2 mutants immunized with thymocytes compatible with standard inbred strains. The phenomenon observed appears to have several features in common with antigenic competition. We propose that the requirement forH-2 compatibility in the anti-Thy-1.1 response may be the expression of a general requirement of T cells to recognize an antigen in the context of the H-2 molecule.

Notes: Abstract Mutantt haplotypes derived from thet 6 haplotype were typed forH-2. The mutantt h2 that arose fromt 6 due to crossing over in the region betweenT andtf had, as expected, lost theH-2 haplotype characteristic oft 6. The haplotypest h17,t h18, andt p1, which also arose by recombination, but which represent the complementary crossover products, including the distal part of thet 6 haplotype, carried the sameH-2 type ast 6. This suggests that crossing over betweentf andH-2 is suppressed int h17 andt 18. This in turn suggests that mutantt haplotypes suppress crossing over for that part of thet chromatin that they still retain. The origin oft h7, which apparently did not include any crossover distal toT, and which retains the crossover-suppressing property oft 6, retains thet 6 H-2 type. Unexpectedly, J h20 , which expressestf and was at first thought to have arisen due to crossing over, also retains theH-2 type oft 6. This provides part of the evidence thatt h20 arises fromt 6 not by crossing over, but by a small deletion, and hence that duplication and deletion are possible modes of origin of mutantt haplotypes.

Notes: Abstract The control of the ability to respond to three doses of ovalbumin has been studied in an attempt to find the minimum dose of antigen necessary for activation of primary antibody response and delayed type hypersensitivity response. In seven of the ten mouse strains studied, concordance of the minimum dose needed to elicit the two responses was observed. Discordance is found in the other strains, suggesting that the ability to respond to ovalbumin is independently controlled in several cells. The antibody and delayed type hypersensitivity responses to ovalbumin are controlled by at least two genes, one localized in the major histocompatibility complex.

Notes: Abstract An informative family, in which parents shared HLA-Dw and Ia-like DRw (Ly-Li) antigens, was used to produce PLTs between members either phenoidentical for both Dw and DRw determinants or incompatible for Dw specificities only. These PLTs were restimulated by members of the family: two PLTs, although in DRw identity, reacted against members of the family bearing one maternal (c) and/or one paternal (a) haplotype. A third PLT also developed in DRw identity reacted with members bearing the other maternal (d) haplotype. Population studies with one of these PLTs did not show any correlation with Dw or DRw specificities. Family studies are in keeping, but do not demonstrate an HLA linkage. The data suggest that, along with the stimulating products (PLA) identical or closely related to the DRw determinants, other stimulating products (PLB), also probably HLA-linked, exist. Furthermore, one of the PLTs was produced without a primary MLR.

Notes: Abstract Murine T lymphocytes incubated in a mixed lymphocyte culture with allogeneic lymphocytes incompatible for theH-2 region or subregions thereof rapidly develop insulin receptors. In contrast, T cells cultured with syngeneic orH-2- andMlslocus compatible cells do not develop insulin-binding sites. The emergence of insulin receptors is probably an early premitotic event.

Notes: Abstract Secondary MLR (PLT) can be generated against stimulatory products (PLA), coded for by theHLA-D region, which are either identical or closely related to the Ia-like DRw antigens. Other stimulatory products (PLB), different from the former but probably alsoHLA- linked, have been demonstrated by generating PLTs in PLA phenoidentity between responding and stimulating cells. Likewise, in PLB phenoidentity, PLTs are sensitized only against the PLA products. PLA and PLB products could be different determinants controlled by the same gene(s) or different genes, probably closely linked in theHLA complex.

Notes: Abstract Reciprocal radiation bone-marrow chimeras were produced between the standard C57BL/6 (=B6) and the mutant B6.C-H-2 ba (=Hz1) strain. When infected with vaccinia virus, these chimeras, as well as an (Hz1 × B6)=→ Hz1 chimera, produced cytotoxic cells that killed vaccinia-infected H-2KkH-2Db target cells but failed to kill virus-infected H-2KbH-2Dd cells. Virus-infected (Hz1 × B6)F1 → B6 chimeras, however, killed both types of target. These experiments demonstrate strict T-cell specificity capable of differentiating between two molecules that apparently differ by a single amino acid substitution.

Notes: Abstract A gene controlling high responsiveness of lymphocytes to in vitro stimulation by PHA was transferred from the Lewis strain of rats to the BN background by ten generations of backcrossing. The high-responder phenotype was initially defined on the basis of incorporation of3H-thymidine, but we show that this trait also involves higher levels of mitotic activity than are observed with low responder lymphocytes. This gene is not closely linked to any histocompatibility locus which could be detected by skin grafting, and it does not appear to affect the proportion of T lymphocytes.

Notes: Abstract The characteristics of a strong mouse alloantigen with renal, bone marrow, and lymphoid expression were studied. This antigen is probably identical to that currently designated Ly-6.2. It was defined by the high-titered (1:1000) cytotoxic activity of three different antisera against peripheral lymphocyte target cells from DBA/2, DBA/1, and a variety of other strains. In the F2 and four backcross generations the genetic control of this specificity segregated as a single autosomal dominant gene. In lymphoid tissues the predominant expression was on T cells but 10–30% of B cells were lysed by these antisera. The specificity was expressed strongly in kidney, as shown by sequential absorption, in amounts equal to or greater than the amount in lymphoid tissues. Comparison to the rate of absorption of H-2 by kidney indicated that this antigen may be expressed in amounts comparable to an H-2 antigen in kidney. Immunization with kidney tissue resulted in a strong cytotoxic antibody response. The number of bone marrow cells expressing this antigen (40–50%) was well beyond what could be accounted for by T lymphocytes in bone marrow. In addition, a nonlymphoid tumor, the P815Y mastocytoma, was positive by cytotoxicity and by absorption. The extensive nonlymphoid expression and antigenic strength of Ly-6.2 raises the possibility that this serologically defined lymphocyte alloantigen will have histocompatibility effects when allografts of the appropriate tissues are examined.

Notes: Conclusion The major accomplishment of the Workshop was probably the realization of many of its participants that most of the 21 availableH- 2 variants aretrue mutations very likely derived from single nucleotide substitutions. Any theory of the pleiotropic effect of theH- 2 genes must now take this fact into account; such theories must also consider the observation that a wide variety of immunological phenomena are affected byH- 2 mutations and thus, apparently, are controlled by a single gene.

Notes: Abstract The unresponsiveness to LPS detected in C57BL/10Cr mice is inherited as a recessive trait and is determined by an autosomal gene linked to theMup-1 locus on chromosome 4. Since no complementation for LPS responsiveness was observed in F1 hybrid mice between C3H/HeJ and C57BL/10Cr, we conclude that C57BL/10Cr mice carry a defective allele at the sameLps locus, previously identified by the mutation detected in the C3H/HeJ strain.

Notes: Abstract The heavy and light chains of pooled antibodies of the hybodont shark,Heterodontus francisci (horned shark), were subjected to amino acid sequence analysis. Yield determinations showed that more than 90% of the available polypeptides in the respective pools were sequenced. The heavy chains were homogeneous in the initial framework segment and showed a sequence homology of approximately 70% with the corresponding region of the more recently evolved nurse shark and a 45% homology with a human myeloma heavy chain. The light chains were less homogeneous and not identifiable as either kappa or lambda chains as known in higher species. The first half-cystine characteristics of the variable domain intrachain disulfide bridge of immunoglobulins was present in the same position (22 for heavy chains; 23 for light chains) in the horned shark as in mammalian species. The sequence analysis also suggested the presence of a hypervariable region in the horned shark light chains. The combined data imply that the antigen-binding function of immunoglobulins is mediated in much the same manner in this primitive shark as in more recently evolved species, including mammals.

Notes: Abstract Evidence is presented for a crossover between the genes coding for the serologically determined (SD) antigens on erythrocytes and an immune response gene (Ir-GAT) controlling immune response to the synthetic polypeptide GAT within theB complex, the MHC of chickens. TheIr-GAT 1 andIr-GAT 19 alleles control low and high immune response to GAT, respectively. Both low and high responders were recovered as recombinants fromB 1 B 1 andB 19 B 19 birds. The low-responder haplotypes are homozygous for theIr-GAT 1 allele and the high-responder haplotypes carry theIr-GAT 19 allele. Mortality forB 1 B 1 nonresponder birds was 39%, compared with 19% for theB 1 B 1 high responders; this suggests the possibility that genes located within the immune response region of theB complex exert some genetic control over viability and survival.

Notes: Abstract A spectrum of lymphomas, sarcomas, and carcinomas were tested for F1 hybrid resistance after s.c. inoculation of small numbers of cells into syngeneic and F1 hybrid mice. Significant F1 resistance was demonstrated against all tumors tested except one. Backcross and/or congenic inoculation tests showed significantH-2 linkage of hybrid resistance against all lymphomas and leukemias tested. There was no linkage betweenH-2 and hybrid resistance within the more limited group of carcinomas and sarcomas. DifferentH-2-linked resistance genes were shown to act against different lymphomas, including some that were induced by the same agent. Some lymphomas induced by different agents in the same strain were also found to differ in their sensitivity to the sameH-2-linked resistance factor. These data suggest the existence of a polymorphic system, probably pseudoallelic, rather than simply allelic in nature.

Notes: Abstract Seven congenic strains differing from C57BL/10Sn at theH-13 locus have been produced which define fourH-13 alleles. Isografting, exchanging of grafts between sublines, F1 testing, and linkage testing demonstrate the presence of additionalH genes in four of these strains. The medial survival times (MSTs) of skin grafts fromH-13a to unimmunizedH-13b recipients ranged from 69 to 83 days. Rejection across all other barriers was extremely weak with most MSTs being 〉 100 days. Preinjection of donor strain thymocytes caused accelerated rejection of skin grafts fromH-13a toH-13b mice, but had only minimal effect on skin grafts across other barriers. Rejection ofH-13 incompatible grafts was significantly stronger when the donor and host areH-3a than when they wereH-3b.

Notes: Abstract We study the consequences of assigning single letter symbols to operationally defined entities such as genes, antigens, specificities, and antibodies. If this is to be done and if reagents are not specific in recognizing the products of single genes or single antigens, then these entities must be defined by a ‘definition matrix’ to avoid mislabeling a matrix of data. A method is given whereby for a given matrix of data all possible definition matrices consistent with this data can be obtained. In particular, all the ways of labeling by the complex-complex code of Hirschfeld can be so obtained.