133 



always stimiilaled the nerves of the organ by means of a single 

 indnction-shock (make-induction) and read the deviation of a galvano- 

 meter with not too great inertia on a scale. The deviations of such 

 galvanometers are nearly proportional to the average E. M. F. of 

 short currents, if the extei-nal resistance and the path of the current 

 remain constant. The latter condition, however, was surely not 

 complied with at different temperatures. 



From the investigations of Gotch on the capillary electrometer 

 it had already become known that the velocity of the movement 

 at low tempei'ature (3° C.) is i-etarded and differs rather strongly 

 from that at moderate temperatuie (15 — 20° C). Such change in 

 the record of the current must magnify the movements at low tem- 

 peratuie. In that way the difference with those found at higher 

 temperature is bound to become smaller than corresponds to reality 

 and the observed temperatuie-coefficients must be too small as 

 Garti'IN has already observed. Moi'eover, it has become evident from the 

 experiments of Schonbein and Garten, that after indirect stimulation 

 of the electrical organ by induction-shocks a repeated discharge 

 frequently occurs^ which of course does not show up with the slow 

 galvanometer. 



My own experience has shown that especially in the cooled organ 

 this repeated discharge occurs veiy frequently. In tiiis way the very 

 low temperature-coefficients, found by Berensti*:in and Tschekmak may 

 partly be explained. 



At any rate, it seemed advisable to try to secure more data on 

 the process and the E.M.F. of the shock. Of freshly caught specimens 

 of Torpedo marmorata and T. occalata the electrical organ was 

 prepared free with its nerves after removal of the skin. The organ 

 was now enclosed between two zinc electrodes by means of two 

 rubber rings. Two bars for the conduction of the electrical shock 

 were attached to the zinc electrodes. 



The conductors were passed through a rubber stopper which also 

 held the platinum electrodes used for the stimulation. This rubber 

 stopper served to close a glass-vessel, in which the organ could be 

 enclosed and through which a stream of liquid could be passed. 

 The strength ot the electrical dischai'ge could thus be studied under 

 different circumstances. 



Moreover, a thermometer was inserted into the stopper. If one 

 allows the liquid to flow into the vessel through the lower tube 

 (Fig. 2) and to leave the apparatus by the upper one, it is possible 

 to regulate conditions so as to keep the organ in the fluid and to 

 keep the nerves in the air. 



9* 



