xr 



ELECTRICAL FISHES 



115 



medial to the lateral wall of the organ of Torpedo, it is quite 

 clear why there should, in the fish in air, he a current as 

 stated by Colladon and Matteucci between median and lateral 

 points, from former to latter on the back, and vice versa on the 

 belly. If all the columns were of equal height in both organs, 

 the organs being, moreover, brought together in the median plane, 

 and there united, the centre of the median line would be most 

 positive on the dorsal aspect, most negative on the ventral. : ' On 

 separating the organs again, the most positive and most negative 

 points in each organ would -as du Bois-Eeymond pointed out 



FIG. 270. Schema of current distribution outside the body of Torpedo. (Du Bois-Reyraoml.) 



(in correspondence with the distance between the organs) lie mid- 

 way between the median edge and the centre." There would 

 thus at equal height of all the columns be a P.D. between 

 back and belly in the same direction, although weaker. Reduced 

 height of columns towards the sides, on the contrary, sends the 

 points of greater positivity and negativity to the median border 

 of the organ. There are thus, as du Bois-Reyrnond pointed out, 

 currents in the back of Torpedo from these borders also to the 

 median line, and vice versa in the belly. The accompanying 

 Fig. 270 shows the direction of the lines of currents in a diagram 

 of the fish, after du Bois-Reyniond. Here we see that the curves 

 " not merely radiate from the so-called polar surfaces, but also cut 



