450 



ELECTRO-PHYSIOLOGY 



CHAP. 



sent) is invariably masked by relatively negative polarisation," 

 the reaction of all three electrical fishes will be found to coincide. 

 The augmentation of relatively negative polarisation, as observed 

 by Sachs and du Bois-Eeymond with homodromous currents 

 as also in du Bois-Eeyniond's observations on Grymnotus are thus 

 intelligible, since the resulting polarisation current through the 

 galvanometer may assume different values at different stages of 

 any experiment. The accompanying curves (Fig. 279) will 



elucidate these complicated interference effects of the two simul- 

 taneous directions of polarisation, which from obvious reasons 

 cannot be separated as they are in muscle (du Bois-Eeymond, 

 4 g, p. 36). Fig. 279 (after du Bois-Eeymond) gives a summary 

 of the process in a series of experiments, the two currents being 

 sent alternately through a strip of organ. The abscissae = time. 

 The ordinates in each cut (i. ii. iii. iv. corresponding with different 

 stages of the experiment) express the moment of closure of the 

 galvanometer after the battery circuit has been opened. 



Absolute positive polarisation (in direction of discharge, i.e. 

 from ventral to dorsal surface) is drawn above, absolute nega- 



