432 LIVING TOBPEDOS IN BERLIN. 



fish was then laid on its back. The frog-alarum showed that the 

 violent efforts of the fish to turn over again were accompanied by 

 numerous shocks. In this case the points were on the one side 

 upon the median line, on the other upon the median border of the 

 organ corresponding to the gill openings, and the results of the 

 shock were 160 right sc. and 70 left sc. in the expected direction, 

 that is, from the median line to the border of the organ. 



A shock between the back and belly always shot the scale far 

 out of sight, and in the first experiments, when so many points of 

 great importance pressed for observation, no comparison was made 

 of the strength of Colladon's currents with that of the shock be- 

 tween the polar surfaces. 



On the other hand, in order to be perfectly sure of the existence 

 of the new currents, I did not fail frequently to lead off the shock 

 from symmetrical points. I had, however, a different result from 

 that put forward in Colladon's third proposition (see p. 428), 

 namely, that in continuation of the last experiments there occurred 

 between two points on the ventral surface outwards from the nasal 

 openings a deflection of 160 sc. from right to left ; on another day 

 between corresponding points on the dorsal surface a deflection 

 of 42 sc. from left to right, and between two symmetrical points 

 of the body some centims. behind the organs, 29 sc. in the same 

 direction. When I allowed the left point to stay where it was, 

 and placed the other on the posterior edge of the left pectoral fin, 

 a deflection of 230 sc. was seen in the expected direction, that is to 

 say, from the point nearest the organ towards the more distant one. 



The results observed between symmetrical points show nothing 

 more than that the fish does not give a shock of equal strength 

 with both organs. In both experiments on the ventral surface, as 

 well as one on a later day on the dorsal surface, it usually gave a 

 stronger shock with the left organ. The reason why similar results 

 were not seen by Colladon may perhaps have been that his very 

 strong fishes innervated both organs equally. Perhaps also these 

 results were beyond the reach of the means of observation at his 

 disposal, for in this case the new currents observed by us between 

 the middle line and the median border of the organs must neces- 

 sarily have escaped his notice. 



The importance of the last named currents consists in what 

 follows. De Sanctis objected to my doctrine of the relative im- 

 munity of electrical fish from their own shocks, that he experienced 

 no shock when his hand was inside the body of a Torpedo which 



