LIVING TOEPEDOS IN BERLIN. 457 



Naturally the conception remains possible that both explanations 

 have a foundation in fact ; it certainly is so if irreciprocal resistance 

 is in question ; for there can be no doubt of the existence of positive 

 polarisation, whereas irreciprocal resistance is a new property attri- 

 buted to the organ, the existence of which along- with positive 

 polarisation still requires proof. Until this proof is given, it must 

 be assumed that in an organ preparation of scarcely the size of the 

 well-known group of muscles of the frog, there is always an electro- 

 motive force of 20 Groves. It will l5e easier to believe this when 

 one remembers that in the organ of the living fish when giving 

 a shock, a much greater electromotive force is undoubtedly in 

 operation. But when the force of this organ is brought into 

 conflict with a known force like that of Groves' battery, the 

 astonishing value of this fact is impressed more forcibly upon us. 

 It has indeed only one counterpart, the surprising nature of which 

 we are apt to overlook, namely, the mechanical activity of which 

 the few grammes of water and organic substance which here act 

 electrically are capable when they take the form not of an electro- 

 motive organ, but of muscle 1 . 



What gives in addition special interest to the experiments just 

 described, in which the preparation is short circuited during the 

 continuance of the current by the galvanometer circuit, is the 

 circumstance that Sachs made a similar experiment on Gymnotus 

 with, so far as can be judged, the same result. He kept the current 

 of his seventeen Groves closed through a bit of organ, and led off 

 a branch with the clay points through the galvanometer, the sen- 

 sibility of which was suitably diminished. * When the current was 

 led through the organ in the direction of the shock, the deflection 

 amounted to 80 sc., in the other direction to 95 sc. The deflection 

 remained constant at this point 2 .' Thus Sachs only observed 

 i and i', as the means for observing I and /' were wanting. As 

 therefore he found, as I did in the torpedo, i<i', it is very probable 

 that he would also have found I> I'. 



12. Dependence of the Secondary Electromotive Effects and 

 of the Conductivity of the Organ on its Vitality. 



It has already been pointed out several times that the polarisa- 

 bility of the organ is intimately bound up with its vitality. I have 

 not yet made methodical experiments as to this dependence, and they 

 would be difficult to carry out for the reasons given on p. 445. The 



1 Comp. Mouatsberichte der Akademie, 1858, p. 99. 2 Untersuchungen, p. 218. 



