LIVING TORPEDOS IN BERLIN. 



437 



of electricity which was lost by derivation (see p. 435)- The only 

 other possibility already considered by me in the conclusion of my 

 paper ' On Iodide of Potassium Electrolysis,' namely, that in 

 those experiments in which the Torpedos were observed out of the 

 water, the resistance of the circuit in which the polarisation 

 discharged itself was too great, seems equally improbable consider- 

 ing the sensitiveness of the iodide of potassium. The fish was kept 

 wet with well conducting sea water, the* path of the current through 

 it was short and of large section, and its tissues probably conducted 

 better than those of Malapterurus ; so that the resistance could 

 scarcely be greater than in my experiments on the last mentioned 

 fish l . Under these circum- 

 stances I cannot avoid the 

 suspicion that the secondary 

 spot must have been seen, but 

 was passed over as an in- 

 comprehensible disturbance. 

 Some indication of this ap- 

 pears in Matteucci's paper 2 . 

 In order to put others in 

 a position to repeat my ob- 

 servations in a similar man- 

 ner, I represent in Fig. 1 6 the 

 iodide of potassium electro- 

 lyser long used by me, and- 

 which in my opinion is an indispensable apparatus for the electrical 

 laboratory, but is seldom met with, although very easy to construct. 



1 According to Leon Fredericq the blood of Octopus vulgaris and Astacus marinus 

 contains nearly four times as much salt as that of mammals ; and according to Boll 

 the tissues of Torpedos have a ' physiological ' concentration of 2-5 per cent, solution 

 of chloride of sodium (Untersuchungen, p. 133). Perhaps on this account the 

 tissues of marine animals conduct better. I have not yet found time to decide this 

 point as regards Torpedos. Any other marine fish out of the Aquarium would be 

 equally useful for the purpose. In accordance with Boll's statement the clay used 

 in the Torpedo experiments should have been kneaded with a 2-5 per cent, solution, 

 instead of the usual 0-75. I observed nothing, however, which could be regarded as 

 an unfavourable result of this neglect. A superiority of sea fish over fresh water fish 

 with respect to the ash of their muscles cannot with certainty be deduced from the 

 118 analyses of the flesh of fishes made by Atwater of Middletown, Conn., U. S. A., 

 and published in the Berichte der deutschen chemischen Gesellschaft (vol. xvi. 

 nos. 12, 23, July 1883). The summary of Koenig, however, seems to favour the notion 

 (Die menschlichen Nahrungs- und Genuss- mittel, Berlin, 1883, 2nd ed. pp. 179, 180). 

 According to Weyl the Torpedo organ yields 1-55 per cent, of ash, a quantity rather 

 greater than that of the muscles of river fish in these determinations (Monats- 

 berichte der Akademie, 1881, p. 382). 



2 Gesammelte Abhandlungen,' vol. ii. p. 650. 



Fig. 1 6. 



