The halteres of the blowfly Calliphora

We quantitatively analysed compensatory head reactions of flies to imposed body rotations in yaw, pitch and roll and characterized the haltere as a sense organ for maintaining equilibrium. During constant velocity rotation, the head first moves to compensate retinal slip and then attains a plateau excursion (Fig. 3). Below 500°/s, initial head velocity as well as final excursion depend linearily on stimulus velocities for all three axes. Head saccades occur rarely and are synchronous to wing beat saccades (Fig. 5). They are interpreted as spontaneous actions superposed to the compensatory reaction and are thus not resetting movements like the fast phase of vestibulo-ocular nystagmus in vertebrates. In addition to subjecting the flies to actual body rotations we developed a method to mimick rotational stimuli by subjecting the body of a flying fly to vibrations (1 to 200 m, 130 to 150 Hz), which were coupled on line to the fly's haltere beat. The reactions to simulated Coriolis forces, mimicking a rotation with constant velocity, are qualitatively and to a large extent also quantitatively identical to the reactions to real rotations (Figs. 3, 7–9). Responses to roll- and pitch stimuli are co-axial. During yaw stimulation (halteres and visual) the head performs both a yaw and a roll reaction (Fig. 3e,f), thus reacting not co-axial. This is not due to mechanical constraints of the neck articulation, but rather it is interpreted as an advance compensation of a banked body position during free flight yaw turns (Fig. 10).     

Optical properties of the ocelli of Calliphora erythrocephala and their role in the dorsal light response

The 3 ocelli of the blowfly Calliphora erythrocephala, grouped close together on the top of the head (Fig. 1), have large, extensively overlapping visual fields. Together they view the entire upper hemisphere of the surroundings plus part of the lower hemisphere (Figs. 5, 7). It is shown for the lateral ocelli that despite the underfocussing of the ocellar lens large patterns are imaged on the receptor mosaic. Because of the astigmatism of the lens, patterns in longitudinal orientations are more accurately represented than in others (Fig. 3). Nevertheless, an artifical horizon rotated around the long axis of the animal does not elicit head roll. Likewise, changes of overall brightness in the visual field of the median and one lateral ocellus elicit only weak phasic-tonic dorsal light responses of the animal which supplement the tonic dorsal light responses mediated by the compound eyes (Figs. 9, 10). Our results show that, in Calliphora, the ocelli have little influence on head orientation during flight, and must be assumed to serve other functions.Abbreviations body pitch angle - head-tilt angle - DNOVS descending neuron of the ocellar and vertical cell systems - HR head roll - spatial wavelength - R roll angle - SD standard deviation     

Proprioceptors and sensory nerves in the legs of a spider,Cupiennius salei (Arachnida,Araneida)

Summary Retrograde CoS-impregnation was used to trace and map the course of sensory nerves and the distribution and innervation of the various proprioceptor types in all leg segments of Cupiennius salei, a Ctenid spider.1. Sensory nerve branches. In both the tibia and femur, axons of all proprioceptor types ascend in just two lateral nerves which do not merge with the main leg nerve until they reach the next proximal joint region. In the short segments — coxa, trochanter, patella, and tarsus — axons of the internal joint receptors often run separately from those of the other sensilla. Axons of the large lyriform slit sense organ at the dorsal metatarsus and of the trichobothria join with only a few hair axons and form their own nerve branches (Figs. 1, 2, 3).2. Proprioceptors. Each of the seven leg joints is supplied with at least one set of the well-known internal joint receptors, slit sensilla (single slits and lyriform organs), and long cuticular hairs. In addition, we found previously unnoticed hair plates on both sides of the coxa, near the prosoma/coxa joint; they are deflected by the articular membrane during joint movements (Fig. 4).3. Sensory cells and innervation. CoS-impregnation shows that each slit of the slit sense organs — be it a single slit or several slits in a lyriform organ — is innervated by two bipolar sensory cells (Fig. 6). We also confirm previous reports of multiple innervation in the internal joint receptors and in the long joint hairs and cuticular spines.Most of the ascending nerve branches run just beneath the cuticle for at least a short distance (Fig. 5); hence they are convenient sites for electrophysiological recordings of sensory activity even in freely walking spiders.     

The development of the static vestibulo-ocular reflex in the Southern Clawed Toad,Xenopus laevis

Summary Acute hemilabyrinthectomized tadpoles of the Southern Clawed Toad (Xenopus laevis), younger than stage 47 (about 6 days old), perform no static vestibulo-ocular reflex (Fig. 1). Older acute lesioned animals respond with compensatory movements of both eyes during static roll. Their threshold roll angle, however, depends on the developmental stage. For lesioned stages 60 to 64, it is 75° while stage 52 to 56 tadpoles respond even during a lateral roll of 15° (Figs. 1 and 2). Selective destruction of single macula and crista organs revealed that the static vestibulo-ocular reflex is evoked by excitation of the macula utriculi (Figs. 3 and 4) even in young tadpoles.The results demonstrate that bilateral projections of the vestibular apparatus must have developed at the time of occurrence of the static VOR, that during the first week of life the excitation of a single labyrinth is subthreshold (Fig. 1). We discuss the possibility whether the loss of the static VOR during the prometamorphic period of life (Fig. 2) is caused by increasing formation of multimodal connections in the vestibular pathway.Abbreviations eye angle - roll angle - () response characteristic - A response amplitude - G response gain - VOR vestibulo-ocular reflex     

Response characteristics of cold cell on the antenna ofLocusta migratoria L.

Summary The dendritic outer segment of the cell which is most likely the cold unit in the poreless coeloconic sensilla onLocusta migratoria antennae, has finger-like projections up to 1.5 m long and 0.13 m thick (Fig. 1). This unit responds to constant temperature, to slowly changing temperature and to step changes. Under stationary conditions impulse frequency attained 35 imp/s. Between 14 °C and 41 °C the higher frequencies were associated with the higher temperatures (Fig. 5). In this range the differential sensitivity is positive but not large: + 0.8 (imp/s)/°C. Its resolving power for steady temperature is 4.7 °C.Downward step changes produced by shifting between airstreams at different temperatures yield far higher frequencies (Figs. 2, 3). Step amplitudes were between –0.1 °C and –12 °C; the conditioning temperature from which the steps were initiated, was between 16 °C and 33 °C. Frequency peaked during the first 50 ms after stimulus onset (Fig. 2) and reached its highest values (310–340 imp/s) at initial temperatures above 30 °C and steps larger than –10 °C (Fig. 4). The mean differential sensitivity from 23 curves was –19 (imp/s)/°C and the resolving power 0.6 °C.During slowly changing temperature the impulse frequency was governed by two parameters simultaneously: ambient temperature and its rate of change. Rates were between 0.001 °C/s or less, and 0.03 °C/s in either direction. Frequency was higher during slow cooling at a given temperature than during slow warming (Fig. 6). The average differential sensitivity to the rate of change was –210 (imp/s)/(°C/s). Further, the larger responses to cooling developed at lower ambient temperatures (differential sensitivity: –1.0 (imp/s)/°C). It is to be noted that this sign is negative, in contrast to the sign for differential sensitivity to constant temperature and also for the influence of initial temperature on the response to downward step changes.Abbreviations b Slope of characteristic curve, differential sensitivity - F impulse frequency in imp/s - imp/s impulses/s - P _w partial pressure of water vapor in torr - r correlation coefficient - T temperature in °C - T T-step - x resolving power in °C     

Observations on the leg receptors ofCiniflo (Araneida: Dictynidae)

Summary The curved, blunt-tipped hairs on the legs ofCiniflo have a structure characteristic of contact chemoreceptors. Using a hair tip recording technique, it has been possible to confirm that these sensilla do respond to contact stimulation by certain chemical substances (Figs. 1 and 3). A few experiments were also performed onTegenaria (Fig. 2). So far, positive responses to some monavalent salts (Figs. 1 and 2) and hydrochloric acid (Fig. 3) have been established, involving perhaps 5 to 6 chemoreceptor units in all. However, each sensillum is known to have 19 chemoreceptor cells and thus most of the reaction spectrum of the sensillum remains unknown. The suggestion that, in contrast to insect contact chemoreceptors (which usually have only 4–7 sensory units), some of the dendrites may be very specific receptor units and are perhaps involved in the detection of contact pheromones or other equally specific substances, is discussed.One of the authors (DJH) would like to thank the Science Research Council for a research studentship, during which this work was carried out. Thanks are also due to Mr. J. Scott, Mr. C. Gilbert and Mr. R. Stevenson for their excellent technical help.     

Antennal warm and cold receptors of the cave beetle,Speophyes lucidulus delar., in sensilla with a lamellated dendrite

Summary Electrophysiological examination of the 2 black-hair sensilla on the antennae of both larval stages of the cave beetle,Speophyes lucidulus, has revealed in each a pair of antagonistic thermal receptors (Fig. 1). Each sensillum was known to house the dendrites of 2 sensory cells which are associated with the extensively lamellated dendrite of a third (Corbière-Tichané 1971). One unit, a cold receptor, responds to temperature drops of 1 to 7 °C from initial temperatures between 9 and 14 °C with impulse frequencies up to 200 imp/s (Figs. 3, 4). Its antagonist, encountered less than 10% as often, is a warm receptor which responds with similar impulse frequencies to rapid rises in temperature from the same 9–14 °C (Figs. 3, 6). As indicated by the average gain of 24 imp/s for an increase of 1 °C in temperature drop, the cold unit appears almost twice as sensitive to sudden temperature change as the warm unit (14 (imp/s) °C). Examination of response scatter indicates that the average cold unit should on the basis of a single pair of responses be able to designate the greater of two temperature drops between 1 and 7 °C with 90% probability when they differ by 0.7 °C (Fig. 5). Though not yet definitive, evidence is accumulating that the third physiological unit is a dry air receptor.Abbreviations F impulse frequency in imp/s - Fc F as calculated - Fm F as measured - imp impulses - Pw partial pressure of water vapor in air - Ps saturation pressure of water vapor - r regression coefficient - T temperature - difference in Supported by the Deutsche Forschungsgemeinschaft, Sonder forschungsbereich 4, Projekt DThe authors wish to express their indebtedness to Dr. Renate Beinhauer, Faculty of Natural Sciences I — Mathematics, Univ. of Regensburg, for her help in applying statistical methods in determining resolving power.     

Body movements and retinal pattern displacements while approaching a stationary object in the walking fly,Calliphora erythrocephala

When a walking fly approaches a stationary object two types of body movements are distinguishable. Type I body movements are characterized by low frequencies (0.4–1.3 Hz) and large amplitudes (28–65°). Superimposed on these movements are type II body movements which are characterized by high frequencies (7.3–10.6 Hz) and small amplitudes (5.9–8.2°) (Figs. 3–6; Table 1). Type II movements occur no matter whether the fly is fixating a pattern or orientating itself in homogeneous surroundings without any pattern. In contrast, only 72% of the flies with immobilized heads and 62% of the flies with movable heads make type I body movements. The amplitude of type I and type II body movements increases slightly after immobilization of the head. Binocular as well as monocular pattern projection occurs for the whole walking trajectory (Fig. 7–9). Monocular pattern projection seems to be more frequent in flies with immobilized heads than in those with movable heads. The degree of pattern fluctuations in the visual field of the flies increases slightly along the walking trajectory. Near the starting point in the centre of the arena it amounts to 5–7°, while at the end of the walking trajectory it amounts to 8–10° (Table 2). The following conclusions and hypothesis can be drawn from these experiments. 1. The graph BT for the direction of the fly's logitudinal axis can be approximated by the first derivative of the walking trajectory WT, that means, dWT(x)/dxBT(x) (Fig. 11). 2. The amplitudes of type II body movements are caused by the alternating movements of the legs during forward motion, while type I body movements are classified as exploring movements. During evolution of visually guided behaviour it is possible that blowflies have adapted their elementary movement detector system to type II body movements. 3. The types of pattern projection into the visual field of the fly while approaching an object can be explained by a simple neuronal network characterized by either inhibitory and/or excitatory influences of the visually activated neurones on the motor neurones generating the propulsive forces, that means the forward motion. In addition it is postulated that the large frontal and antero-lateral receptive fields of these neurones are not coupled with the motor centres on the same side of the body (Fig. 12).     

Deep-sea nematodes from the Indian Ocean: new and known species of the family Comesomatidae

Twelve new and known species of the genera Sabatieria,Cervonema, Paramesonchium, Hopperia and Dorylaimopsis and one new genus, Kenyanema aredescribed from the Indian Ocean and S. pisinna Vitiello,1970 from the Mediterranean Sea. Sabatieria lucia sp. n.is characterised by short but distinct inner and setiformouter labial sensilla and long (4–5 µm or 30–33% hd)cephalic sensilla; S. conicauda Vitiello, 1970, ischaracterised by tiny inner and outer labial sensilla andsetiform cephalic ones and short and thick cylindrical tail;Sabatieria pisinna is characterised by short innerand outer labial sensilla, setiform (3µm long) cephalicsensilla, multispiral amphids with 3.25–3.5 turns and a tailwhich is conical in the anterior 2/3 and posterior 1/3cylindrical; Cervonema tenuicauda Schuurmans Stekhoven,1950, is characterised by anterior sensilla in twocircles which are equal in length (3µm long), multispiralamphids with 3–4 turns and located at 1.5 times hd from theanterior end, simple spicules one abd long and 6–7 fineprecloacal supplements; Cervonema minutus sp. n.characterised by an extremely attenuated anterior end,spiral amphids with 4–5 turns (80–90% cbd) and short,simple spicules (0.8 abd long); Cervonema gourbaulti sp.n. characterised by long (4–5 µm) labialand cephalic sensilla, spiral amphids with 5–6 turns(73–88% cbd) and an elongate crenate terminal pharyngealbulb; Paramesonchium mombasi sp. n. characterised bylong labial (5 µm) and cephalic (21 µm) sensilla thatare close together and wide amphids (80–90% cbd); Kenyanema monorchis gen. et sp. n. characterised bya head region narrower than the rest of the body, fourcephalic sensilla (3 µm long) and spiral amphids with1.5–2 turns; Hopperia indiana sp. n. characterised byshort conical anterior sensilla, arcuatespicules that have a velum and a gubernaculum with a longand sharp pointed apophysis; Dorylaimopsis coomansi sp.n. characterised by long (8–10µm) cephalic setae,cuticular punctation with lateral differention of irregularlyarranged dots at the pharyngeal region and 1–3longitudinal rows of dots posterior of the pharynx; spiculeswith a unique shape; Dorylaimopsis gerardi sp. n.characterised by short setiform labial and long (6–7 µm)cephalic sensilla, punctated cuticle with lateraldifferentiation of irregularly arranged dots at firstthen three or four irregularly arranged longitudinal rows atthe pharyngeal and tail regions and two regularly arrangedlongitudinal rows of dots on the rest of the body, aconico-cylindrical tail with a distinctly swollen tip;Dorylaimopsis variabilis sp. n. is characterised byshort labial and setiform cephalic sensilla (33–58% hd),multispiral amphids with three turns, cuticular punctationswith lateral differentiation of three longitudinalrows at the pharyngeal and tail regions and two longitudinalrows on the rest of the body, spicules that are thin andslightly arcuate. The position of S. pisinna accordingto the grouping of Platt, 1985 of Sabatieriaspp. is also discussed. Kenyanema monorchis representsthe first monorchic species in the family.     

Detection of vibrations in sand by tarsal sense organs of the nocturnal scorpion,Paruroctonus mesaensis

Summary The scorpionParuroctonus mesaensis locates prey by orienting to substrate vibrations produced by movements of the prey in sand. At the end of each walking leg of this scorpion there are two sense organs, the basitarsal compound slit sensillum and tarsal sensory hairs (Figs. 1, 3) that are excited by substrate vibrations conducted through sand. The slit sensilla appear to be most sensitive to surface (Rayleigh) waves while the tarsal sensory hairs respond best to compressional waves (Fig. 7). Both mechanoreceptors were activated by nearby disturbances of the substrate (Fig. 6) but only the slit sensilla responded to insects moving more than 15 cm away. Both receptors are highly sensitive to small amplitude (less than 10 Å) mechanical stimuli applied to the tarsus (Fig. 5).Behavioral studies of scorpions with ablated sense organs (Fig. 2) indicate that the basitarsal compound slit sensilla are necessary for determining vibration source direction.Abbreviation BCSS basitarsal compound slit sensillum (a) Supported by PHS Environmental Science and Regents Intern Fellowships (PB), and by intramural research funds from the University of California (RDF)     

Movement sensitivities of cells in the fly's medulla

Summary Intracellular recordings were made in the medullae of intact, restrained females ofCalliphora vicina that faced a hemispherical, minimum-distortion surface upon which moving patterns and spots were projected from the rear (Fig. 2). In the distal medulla, noisy hyperpolarizations to light, most likely recorded in terminals of laminar (L) cells, had flicker-like oscillations to moving gratings of 15° spatial wavelength but not of 2.5° spatial wavelength (Fig. 3). Medullary (M) cells penetrated distally responded to grating movements with similar but depolarizing oscillations, in one cell 180° out of phase with a nearby laminar response (Figs. 4–6).A characteristic movement response recorded from most medullary cells consisted of abrupt, maintained nondirectional depolarizations in response to movements of gratings, often with directional ripple or spikes superimposed. When directions of movement reversed, there were brief repolarizations, but when movements stopped, depolarizations decayed away more slowly (Figs. 7 and 8). Magnitude of responses increased with increasing speeds of both 15° and 2.5° gratings (Figs. 9–11). In some cells, there were delayed decays of responses after stopping (Fig. 12). Still other cells seemed to receive inhibition from other, characteristically responding cells (Fig. 13).Receptive fields tested were simple and usually large, with only a suggestion of surround inhibition (Fig. 14). In general, intensity and position were interchangeable over a cell's receptive field (Figs. 15 and 16). Moving edges and dark spots elicited responses primarily within receptive field centers (Figs. 18–20).It is argued that waveforms of characteristic movement responses can be explained by multiplicative inputs from L- and M-cells to movement detectors (Figs. 21–26).Abbreviations L cells laminar (monopolar) cells - M cells medullary cells     

The effects of assay temperature upon the pH optima of enzymes from poikilotherms: A test of the imidazole alphastat hypothesis

Summary A study of the thermal responses of Na-ATPase and NaK-ATPase activities in microsomes prepared from gill tissue of rainbow trout (Salmo gairdneri) revealed further evidence that the two activities are distinct from one another. Arrhenius plots of the NaK-ATPase from sea water-adapted fish and the Na-ATPase from fresh water-adapted fish were linear (Fig. 4) with estimated activation energies of 19.5 and 7.7 kcal/mole, respectively. The Na-ATPase and NaK-ATPase both showed optimum activity at 45°C (Figs. 2 and 3). The Mg-ATPase from fresh water fish showed a distinct temperature optimum at 24°C (Fig. 1) while Mg-ATPase activity from sea water fish was optimum at temperatures of about 15–24 °C (Fig. 3). The Na⁺ dependence of the Na-ATPase and the NaK-ATPase was examined at an assay temperature of 37 °C (Fig. 5) and the results compared with those obtained at 13 °C. No apparent differences were noted for the Na-ATPase, but with the NaK-ATPase both theK _0.5 for Na⁺ and optimum Na⁺ concentration increased at the higher assay temperature. Finally, evidence is presented showing the Na-ATPase to be distinct from Mg-ATPase activity in fresh water trout gill microsomes.Abbreviation HEPES N-2-hydroxyethylpiperazine-N-2-ethane-sulfonic acid     

Response characteristics of a cold receptor in the stick insectCarausius morosus

Summary The cold cell in the easily identified mound-shaped sensillum on the 12th segment ofCarausius morosus' antennae responds to downward temperature (T) steps from about 15 °C with a sharp rise in impulse frequency (F). Responses to similar steps from higher initial temperatures are smaller (Figs. 1, 3, 4). As initialT increases from 16 °C to 31 °C, differential sensitivity to downward steps falls off by a factor of 27: to yield an average increase inF of 1 imp/s, steps down from 31 °C must increase by 1.7 °C; steps down from 16 °C, by only 0.06 °C (Fig. 5). Resolving power forT-steps at mid-range initial temperatures is about 0.7 °C, i.e. the probability that a single cold cell at average differential sensitivity will correctly discriminate between twoT steps 0.7 °C apart is 90% when the cell is presented with each step just once.The same cold cell also displays a clear dependence on steadyt between 14 °C and 24 °C (Figs. 7, 8). The static discharge rate of a single cell at average differential sensitivity has a resolving power of about 0.9 °C for steadyT. — The static discharge is not affected by the amount of water vapor in the stimulating air (Fig. 9).Abbreviations F impulse frequency in impulses per second (imp/s) - Pw partial pressure of water vapor in torr - r correlation coefficient - T temperature in °C - T step change inT     

The motor pattern of locusts during visually induced rolling in long-term flight

Desert locusts (Schistocerca gregaria F.), mounted in a wind tunnel on a low-mechanical-impedance torque meter, flew for at least 30 min in the posture typical of long-term flight. As they flew, they were induced to rotate about their long axis (roll) by rotation of an artificial horizon. All maintained departures from the horizontal attitude were brought about actively, by the animal's own efforts. In the roll maneuver, the hindlegs and abdomen were bent toward the side ipsilateral to the direction of rotation. However, these rudderlike movements were not adequate to initiate and maintain a constant roll angle.During a roll, there was a change in the pattern of excitation of all the wing muscles that were monitored: the depressorsM81, 97, 99, 112, 127, and 129, and the elevatorsM83, 84, 89, 113, 118, 119 (numbering according to Snodgrass 1929). Hence all 12 muscles probably not only provide power for the flight but also steer it. Evidently, then, for these muscles a rigid distinction between power and steering muscles is not appropriate.The period of the contraction cycle changed in correlation with the roll angle, but was not a parameter for control of the roll maneuver, because the changes were the same in all muscles (Fig. 2).Even with constant burst length, the phase shifts between the muscles changed. These changes were the main control parameter for rolling (Figs. 3–9).There was a latency coupling between elevators and the following depressors (Fig. 3).The changes in phase shift were tonic or phasic (sometimes phasic-tonic) in different muscle pairs (Fig. 4).When a roll angle of ca. 15° was adopted, the phase shifts between depressor muscles in a given fore- or hindwing (e.g.,M127R vs.M129R) changed by about 5 ms, whereas the elevators changed by less than 1 ms (Fig. 6).The phase shifts between the anterior elevators and depressors of a given wing, as well as the posterior elevators and depressors, changed by ca. 5 ms (in some cases with different time courses) when the animal rolled to an angle of ca. 15° (Fig. 7).The changes in phase shift between muscles of the fore-and hindwing on one side of the body amounted, as a rule, to about 4 ms at ca. 15° roll (Fig. 8).Corresponding muscles on the two sides of the body change in phase with respect to one another by as much as 10 ms (Fig. 9). The phase shifts of all such contralateral muscle pairs except for the posterior basalar muscles,M127, have the same sign, such that the muscle ipsilateral to the direction of rotation becomes active sooner.     

Visual pattern discrimination as an element of the fly's orientation behaviour

Summary The visually guided orientation behaviour of stationarily flying Musca domestica (females) has been investigated. Under such conditions, the flight activity does not influence the visual stimulus (openloop) and the tendency of a fly to orientate towards some visual object can be recorded as a yaw torque reaction (orientation response).—Orientation responses to flickering stripes reveal two different mechanisms of visual integration, namely a local flicker detecting mechanism and a specific kind of dynamic lateral interactions (Figs. 3, 5). The lateral interactions are mediated by a field of interconnections of receptors which are separated by at least 4 to 6 vertical rows of ommatidia (Figs. 3, 8). While stimulation of not more than 3 vertical rows of ommatidia activates only flicker detection, stimuli of more than 6° width may in addition exert an excitatory or an inhibitory influence as a consequence of the associated nonlinear interactions (Figs. 5, 7). The relevance of these lateral interactions for tracking and chasing behaviour is discussed. It is suggested that the fly's visual pattern discrimination rests essentially on these lateral interactions.     

The influence of head position on the flight behaviour of the fly. Calliphora erythrocephala

The heads of flies were passively turned during fixed flight (open loop conditions). The turning stimuli had ramp-shaped onsets. The resulting torque produced by the thorax was plotted as a function of the degree of head-turn.Directional, passive turns of the head evoke active turning tendencies (yawing forces) of the same sign from the thorax. The strength of these tendencies is dependent on the size of the given angle through which the head was turned. The cushion of sensory hairs on the neck (prosternal organ) is very important in the elicitation of the turning tendencies. The results which have been obtained indicate that the position of the fly's head has a substantial influence on the magnitude of the turning tendencies elicited by visual stimuli.