LIVING TOBPEDOS IN BERLIN. 519 



communicated in the book on the gymnotus loc. cit. In Prof. 

 Christian! 's experiments the tap- water conducted 126-57 times 

 worse than the sea- water of the Aquarium. Our numbers give 



0-3202:37-955 = i : 118-52. 



A closer agreement is scarcely attainable in such circumstances. 



It is apparent that even in the homodromous direction, in which 

 the organ conducts best, it conducts scarcely half as well as frog 

 muscle parallel to the fibre, and 7-5 to 12 times worse than the sea- 

 water of the Aquarium. The ratio would be still more unfavourable 

 with sea- water from the Mediterranean, which conducts nearly 150 

 times better than tap-water. But in the heterodromous direction, 

 the organ conducts, even 20 to 58 times worse than sea- water. 



Our method does not allow of our obtaining corresponding 

 numerical determinations for the transverse conduction of the 

 organ. That the electrical organ does conduct quite reciprocally 

 in a transverse direction, I showed a long time ago in the 

 case of the Malapterurus, where it is easy to cut strips of the 

 organ vertically to the direction of shock. I now endeavoured 

 to ascertain, for the organ of the Torpedo at least, how transverse 

 conduction compares generally with homodromous and hetero- 

 dromous conduction. I cut from the organ square slices as 

 uniformly thick as possible, of which one edge was formed 

 of dorsal skin, the opposite one of ventral skin, and the two 

 lateral edges were formed of lateral surfaces of the columns, and 

 sent induction shocks through them, sometimes from belly to back, 

 sometimes from back to belly, sometimes in transverse direction 

 from one lateral edge to the other. In the homodromous direction, 

 the deflections were, for example, 80-7, in the heterodromous 22*5? 

 in transverse direction each way 99. The suspicion might arise 

 that the semblance of better conduction in the transverse direction, 

 is the result of the skin on the dorsal and ventral edge of the slice 

 increasing the resistance, when it is traversed longitudinally. But 

 when I covered the lateral edges with pieces of skin and sent the 

 current through these, the deflection was still 95 sc. ; after removing 

 the artificial covering of skin the deflection was the same, 

 the homodromous on the other hand being now only 75, the 

 heterodromous 18. It thus seems as if the organ conducts in 

 transverse direction, even better than in homodromous. However, 

 I consider this result as not yet certain, on account of the defective- 

 ness of the mode of experiment. 



