LIVING TORPEDOS IN BERLIN. 429 



(see Fig. 15) ; by so much, therefore, may the electromotive force of 

 the median columns be greater than that of the outer ones. This 

 explains why when a Torpedo gives shocks in the air, a current is 

 observed in the back from the median to the outside points, and on 

 the belly in the reverse direction. In Torpedos under water this 

 arrangement seems to be adapted to its purpose, inasmuch as the 

 curves of currents proceeding from the higher columns have 

 almost the same strength as the shorter ones which proceed from 

 the lower columns. 



As Matteucci gradually altered his opinions and allowed that the 

 current flowed on the back from the thicker to the thinner parts, 

 and also indicated the existence of a stronger current between back 

 and belly in the thicker than in the thinner, so he later (without 

 mentioning me) adopted the explanation given by me in the ' Pre- 

 liminary Sketch.' I did not, however, adhere to this explanation, 

 for I found later that it was not well founded. By an experiment in 

 which I suddenly plunged into water zinc platinum elements grouped 

 like electrical plates, I imitated, sufficiently for the purpose though 

 very imperfectly, a shock given under water, and thus tested my 

 conclusions regarding its distribution. These observations have 

 already been given in detail, and I will here confine myself to 

 recalling the results. 



An arrangement of electrical plates which corresponds to a slice 

 of the organ of the Torpedo bounded by two cross cuts, in which 

 therefore the number of plates in the columns diminished from the 

 one side to the other, yielded quite regular currents which were 

 directed from the higher to the lower on the positive aspect of the 

 organ, and from the lower to the higher on the negative 1 . It was 

 found however experimentally, as on theoretical grounds might 

 have been anticipated, that Colladon's currents occurred even when 

 there was no difference in the height of the columns. If an 

 electrical organ having columns of the same height were placed in 

 an unlimited quantity of water, the middle districts of the polar 

 surfaces would be relatively the most positive and the most nega- 

 tive. Let us suppose all the columns of the organs of the Torpedo 

 to be of equal height, and the organs to be brought together 

 in the middle plane and there united ; then the middle of the 

 median line would be most positive on the dorsal aspect, most 

 negative on the ventral. Let the organs be again separated, then 



1 Comp. Untersuchungen uber thierische Elektricitat, vol. i. pp. 644 ff. Gesammelte 

 Abhandlungen, vol. ii. p. 688. 



