180 SECONDARY ELECTROMOTIVE PHENOMENA IN 



that of the critical times of closure with the axis of current 

 densities as abscissal axis. It is obvious that the curve of the 

 critical times of closure has a maximum ; in my experiments 

 this maximum lay somewhere between the density of the current 

 generated in 2 Groves, and the critical time of closure then reached 

 was about 5". With 20 Groves it was only about i". If the 

 positive maxima of the individual polarisation-curves are connected 

 by a curve, this curve also shows a maximum with from 20 to 30 

 Groves ; and similarly a curve which unites the negative maxima 

 exhibits a maximum, but does so with I Grove only. 



It remains to give an idea of the amount of these maxima as 

 compared with that of the muscle-current. If I pass through a 

 galvanometer-circuit, in which the group of muscles have been 

 placed as if for a polarisation experiment, an electromotive force 

 of about 0-045 ^ f 55 Raoult corresponding to the force of the 

 whole 1 artificial transverse section of the gracilis or semi-mem- 

 branosus, there follows a deflection of 235-285 8C , the sensitiveness 

 of the galvanometer having been diminished. I noticed the 

 strongest negative polarisation after closure of a current of I Grove 

 for 10', and it gave 423 8C . I obtained the strongest positive 

 polarisation by closure of 20 Groves during o"-o75 ; it amounted 

 to 239", and therefore appeared to have less electromotive force 

 than the muscle-current. We shall soon see, however, that this 

 is a deceptive estimate. What the relation is between the 

 secondary electromotive actions in muscles relatively to their 

 size, and those of other moist porous bodies, has not yet been 

 investigated. 



So far as the above numbers for the position of the maxima, &c., 

 depend on the density of the primary current, they are only applic- 

 able to the particular group of muscles in frogs 22 cm. long, with 

 our method of conduction. Moreover Fig. 5 must not be understood 

 to represent the relation between the numerical values. The avail- 

 able space rendered this impossible. As, for instance, the critical 

 time of closure in our experiments reached at most 5", and the 

 maximum of negative polarisation first appears only at 10-15', ^ ae 

 figure would require to be from 3 to 4 metres long in order to show 

 this maximum at the right place with the same proportional measure- 

 ment as that adopted for the first few seconds. The current 

 densities would require at least five times as broad a space, &c. 



1 Gesammelte Abhandlungen, vol. ii. pp. 193, 243. 



