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Vibration-sensitive units with labyrinth input are studied in the medullary magnocellular region, and in the mesencephalic torus semicircularis and oculomotor nucleus of the thornback ray. Neuronal activity is recorded during delivery of vibratory and acoustic stimuli, and during presentation of static tilt and sinusoidal pitch movement. These stimulation procedures are subsequently combined in order to gain some insight into the potential biological function of these units. The units described fall into three categories. The first group (called VIB I) are highly sensitive to vibration. They project to the torus semicircularis and are probably activated by the macula neglecta. Their responses to vibratory shocks or acoustic click sounds are not affected by simultaneous presentation of static tilt or movement of pitch. However, if exposed to a background of vibration, these units yield responses phase-locked to sinusoidal pitch; they respond poorly to pitch alone or even fail to do so at all without simultaneous delivery of vibration. Since it is uncertain exactly which natural stimuli excite these units, their biological function is still unclear. The units of the second group (VIB II) are less sensitive to vibration, project to the oculomotor nucleus, and possibly receive input from the anterior two thirds of the macula sacculi and/or the lacinia utriculi. The units respond to both tilt and pitch, provided that continuous vibration is delivered at the same time. Unlike the preceding class, their responses to vibratory bursts and acoustic clicks are suppressed during presentation of pitch and static tilt. It is suggested that this type of unit is more likely to be used for vestibular input of tilt and pitch rather than for vibratory and acoustic information. The third group of units (VIB III) is least sensitive to vibration. These units appear to receive input from the macula utriculi and/or the posterior third of the macula sacculi. They discharge poorly during vibratory stimulation, and are able to respond to pitch even without simultaneous delivery of vibration. Their responses to vibratory stimulation are enhanced by static tilt. Apparently, these units are involved in the processing of vestibular input.

Central lateral line pathways were mapped in the thronback ray, Platyrhinoidis triseriata, by analyzing depth profiles of averaged evoked potentials (AEPs), multiunit activity (MUA), and single unit recordings. Neural activity evoked by contra- or ipsilateral posterior lateral line nerve (pLLN) shock is restricted to the tectum mesencephali, the dorsomedial nucleus (DMN) and anterior nucleus (AN) of the mesencephalic nuclear complex, the posterior central thalamic nucleus (PCT), the lateral tuberal nucleus of the hypothalamus, and the deep medial pallium of the telencephalon (Figs. 2, 3, 4, 6, 7). Neural responses (AEPs and MUA) recorded in different lateral line areas differ with respect to shape, dynamic response properties, and/or latencies (Figs. 9, 10 and Table 1). Ipsilaterally recorded mesencephalic and diencephalic AEPs are less pronounced and of longer latency than their contralateral counterpart (Fig. 9 and Table 1). In contrast, AEP recorded in the telencephalon show a weak ipsilateral preference. If stimulated with a low amplitude water wave most DMN, AN, and tectal lateral line units respond in the frequency range 6.5 Hz to 200 Hz. Best frequencies (in terms of least displacement) are 75-150 Hz with a peak-to-peak water displacement of 0.04 micron sufficient to evoke a response in the most sensitive units (Fig. 11A, B, C). DMN and AN lateral line units have small excitatory receptive fields (RFs). Anterior, middle, and posterior body surfaces map onto the rostral, middle, and posterior brain surfaces of the contralateral DMN (Fig. 12). Some units recorded in the PCT are bimodal; they respond to a hydrodynamic flow field--generated with a ruler approaching the fish--only if the light is on and the eye facing the ruler is left uncovered (Fig. 13).

Sinop İli civarından temin edilen 1 kg. ın üzerindeki 200 adet Dikenli Vatoz (Raja clavata L.1758) balığı üzerin de sürdürülen araştırmada, dişi ve erkek balıklarda sırasıy la ortalama toplam uzunluk 69,46 +- 0,67 cm ve 74,59 +- 0,58 cm, kanatlar arası uzunluk 47,92+- 0,46 cm ve 50,44 +- 0,37 cm, toplam ağırlık 2159,02 +- 80,28 gr ve 2719,70 +- 61,90 gr. yene bilen kısım ağırlığı 773,75 + 27,98 gr ve 955,67 +- 24,31 gr, bulunmuştur. Yenebilen kısım oranı dişi balıklarda % 36,53, erkek balıklarda ise % 34,88, besin maddeleri miktarları ise % 77,23 su, % 19,46 ham protein, % 1,30 ham yağ, % 1,48 ham kül ve %53 nitrojensiz öz madde olarak saptanmıştır. The research done over 200 thornback ray weighing at least a kilo each, which have been obtained from the vicinity of Sinop indicated that the total length 69.46+O.67 cm and 74.59+0.58 cm, the disc width 47.92+0.46 cm and 50.44+0.37 cm, total weight 2159.02+80.28 gr and 2719.70+61.90 gr, the weight of the edible part 773.75+27,98 gr and 955.67+24.31 gr on the average in females and males respectively. The rate of the edible part was 36.53 % in female fish and 34.88 ^ in males. Chemical composition of edible part was determined as 77.23 > water, 19. 46 % crude protein, 1.30 % crude fat, 1.48 % crude ash. 55

IN a recent communication1, one of us (O. L.) reviewed the results so far obtained, by the oscillographic method, in the study of the non-acoustic function of the vertebrate ear. In that review a preliminary account was given of the reaction to gravitational stimuli and linear accelerations of the otolith organ in the recessus utriculi of the elasmo-branch labyrinth. It was shown that the otolith organ of the utriculus is sensitive to positional changes about any horizontal axis, and to linear acceleration during straight-line translations. The fact that the organ is not restricted to respond to displacements in only one plane of space invited the conclusion that the utriculus may well be the only otolith organ concerned with the maintenance of equilibrium, leaving the otolith organs of the pars inferior of the labyrinth (sacculus and lagena) free for the reception of vibrational stimuli. This function has, in fact, been conclusively demonstrated to be localized in the pars inferior of the labyrinth of bony fish2,3.

1. 1. Isolated spontaneously beating hearts of five horned sharks, Heterodontus francisci , and four thornback rays, Playtrhinoidis triseriata , have been perfused in vitro at various pressures with a saline medium in order to establish whether or not the pacemakers of these elasmobranchs contained an intrinsic pressure-sensitive rate regulatory mechanism. 2. 2. In the shark hearts 77 per cent and in the ray hearts 88 per cent of the observations yielded positive results. A total of 230 studies were performed on the nine hear from both species. 3. 3. In numerous instances, spontaneously occurring atrioventricular block or arrhythmias, which were observed at low perfusion pressures, were converted to a regular beat when the pressure was augmented sufficiently. 4. 4. The data consistently indicate that the pacemakers of both shark and ray hearts exhibit the fundamental property of intrinsic rate regulation. 5. 5. The data presented in this paper on elasmobranch hearts further substantiate the earlier conclusion that intrinsic cardiac rate regulation represents an ancient and independent phylogenetic development in the pacemakers of many species of animals.

The objective of this study was to determine the current levels of total mercury and methylmercury in the muscle tissues of different fish species caught in the Mediterranean Sea to ascertain whether these concentrations exceed the maximum level stipulated by the European Commission Decision. Total mercury concentrations in the muscles of skates ranged from 0.18 to 1.85 mg/kg (wet weight) (average, 1.00 mg/kg) while levels of 0.11 to 1.92 mg/kg (wet weight) (average, 0.70 mg/kg) and 0.21 to 1.74 mg/kg (wet weight) (average, 0.70 mg/kg) were recorded for blue whiting and red mullet, respectively. For 66.7% of long nose skate samples, 61.4% of thornback ray samples, 42.8% of winter skate samples, and 38% of starry ray samples, the total mercury concentrations exceeded the prescribed legal limit (1.0 mg/kg [wet weight]). Concentrations exceeding the maximum total mercury level stipulated by the European Commission Decision (0.5 mg/kg [wet weight]) were observed in 63.6 and 40% of blue whiting and striped mullet samples, respectively. Mercury was present in the different species almost completely in the methylated form at 55 to 100%. Weekly intakes were estimated and compared with the provisional tolerable weekly intake recommended by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives.

Quelques proprietes respiratoires du sang de la raie (Raia clavata) ont ete determinees avec des echantillons de catheter intravasculaire. Chaque echantillon etait utilise seulement pour deux points de la courbe de dissociation −O2−, parce que les proprietes changent apres une demie-heure. On a constate un effet de Bohr (Δ log P50/Δ pH=−0.25±0.03) ainsi que celui d'Haldane.

IT has been reported that fish do not appear to react to rectilinear accelerations1. However, they have the sense organs to detect such movements; the otolith organs of the thornback ray are sensitive to linear translations in all three planes of space2 and teleosts take up compensatory positions when subjected to centrifugal force3. Some experiments were therefore made to re-examine the reactions of fish to rectilinear accelerations, blinded minnows, goldfish and naturally blind cave characins, Anoptichthys jordani, being used in the preliminary observations. The fish were placed in an enclosed ‘Perspex’ tank, completely filled with water, and mounted on a rubber-wheeled chassis. They appeared to turn about when the tank was accelerated along a bench by hand.