482 LIVING TORPEDOS IN BERLIN. 



electricus for an electromotive action during- rest, that is for an 

 organ-current. This failure must seem strange now that such 

 actions have been demonstrated 1 in the Gymnotus and Torpedo, 

 and as it is alleged even in the imperfect electrical organ of the 

 common skate. It can be explained, neither by the lowered 

 functional activity of the preparations, for they were in much 

 better condition than many preparations of the Torpedo which now 

 gave me the organ-current, nor by the imperfection of the experi- 

 mental method, for I made use of the nerve multiplier ; and the 

 resistance of the old conducting- vessels and of the salt pads covered 

 with thin films of white of egg was certainly less than that of the 

 present unpolarisable apparatus. The polarisation of the platinum 

 in the old conducting vessels is all that remains to explain that a 

 constant weak action might escape me ; it did not, however, prevent 

 my perceiving a slight positivity of the external surface of the skin 

 in comparison with all other natural as well as artificial boundaries 

 of the organ preparation, an action with which, as will now be 

 shown, the organ-current if present would have been of the same 

 order. 



In the Gymnotus, Sachs found points of the skin feebly positive 

 (0-0050 Daniell= 0-0053 Raoult ; see p. 440) in comparison with 

 points of natural longitudinal section not covered with skin and 

 situated in the same transverse plane, as also in comparison with 

 such points of artificial longitudinal and transverse section. In com- 

 parison with the surface of that part of the organ turned towards the 

 head, the skin is feebly positive, electrically the same, or very feebly 

 negative ; and in comparison with the surface towards the tail, it is 

 more strongly positive, as this gives the algebraical sum of the 

 organ current of the length situated between the leading-off points, 

 and of the skin current. In the first adjustment, for example, the 

 force amounted to a mean value of 0-0040, in the second to 0-0195 ; 

 whence by calculation the force of the skin current is found to be 

 0-0155/2=0-00775, and this approximates sufficiently to the direct 

 measurement given above (0-005) 2 - 



The question naturally forced itself upon me, how the skin 

 behaves electromotively in regard to the interior of the organ in 

 the Torpedo. The case is not so simple here as in Malapterurus 

 which is not complicated by any perceptible organ-current, nor as 

 in Gymnotus, where the organ is bounded laterally by skin, 



1 Untersuchungen, etc., p. 169 f. 

 9 Untersuchungen, etc., p. 173. 



