444 ELECTRO-PHYSIOLOGY 



CHAP. 



surfaces i.e. the cross-sections at the head and tail ends of the 

 prisms a current in the direction of the discharge (du Bois- 

 Eeymond's " organ current "), which, however, was again remark- 

 able for its low E.M.F. It usually corresponds with that of a 

 stronger nerve, or weaker muscle (0'15-0'03 Dan.) applied by 

 long and transverse sections, although the strips were about 4 cm. 

 in length and 6-7 sq. cm. diameter. Since there are about 400 

 chambers in 4 cm. of organ, the organ current of each compartment 



can only have an E.M.F. of- = 0'0000375-0'000075 



400 



Dan. There is also a weak current, in the direction of the dis- 

 charge, between two points of the natural long section (i.e. the 

 natural, lateral boundary of the organ). Du Bois-Eeymond, after 

 punching out the electrical lobe in Torpedo, either led off from the 

 skin of the dorsal and ventral surfaces of the vertically dependent 

 fish, or with scissors and scalpel prepared four-sided prisms of the 

 organ, containing a fair number of columns, and bordered by a 

 square piece of skin of 5 6 mm. on the dorsal and ventral surfaces. 

 In the first case there is always a current in the direction of the 

 discharge. " It was most pronounced when the highest prisms 

 were at the medial border of the organ between the leading-off 

 parts, and became weaker in proportion as the parts were brought 

 nearer the thinner, lateral edges of the organ " (4 g). In the 

 excised pieces there was also a P.D. in the same direction on 

 leading off from two points of the lateral surface of the prism, the 

 magnitude of which increased with the distance of the leading-off 

 points. The deflections were, however, very small in the one case 

 as in the other (between 3 and 23 degrees of the scale); the 

 E.M.F. was also considerably less than that of the nerve current 

 in fish (0-005-0-013 Eaoult). For the single plates, du Bois- 

 Eeymond estimated a medium E.M.F. of O'OOOOllV Dan., i.e. three 

 times smaller than that determined for the single plates of 

 Gymnotus. 



Like Eckhardt (11), Gotch (13) ascribes no great importance 

 to this weak electromotive action during " rest," the more so 

 since he failed to discover it in freshly -caught and perfectly 

 uninjured animals. Upon ten fishes he obtained on leading off 

 from two points corresponding with the centre of an organ, and 

 lying opposite to each other on the skin of back and belly, very weak 

 and fluctuating effects, which occurred six times in the direction 



