122 w - M - Bayliss and J. R. Bradford, 



this. As there are many objections to the use of the expressions 

 „negative" and „positive variation" we will discard these terms, and 

 express our results by saying, that the outer surface of the gland be- 

 comes positive or negative as the case may be, premising that the 

 current of rest, which is always previously compensated, is as we 

 have just seen usually of such a nature that the outer surface is 

 negative. 



On stimulating the chorda tympani by an induction current a 

 very well marked deflection of the galvanometer is always observed, 

 of a nature indicating that the outer surface of the gland has oecome 

 more negative. Although in different cases the amount of this deflection 

 varies, yet never have we failed to obtain it. On the other hand al- 

 though this electrical variation is always present, frequently it is not 

 the sole one, but its course is interrupted by a second deflection of 

 an opposite sign, showing the outer surface of the gland to oecome po- 

 sitive. This second variation is by no means always present, in fact 

 in the majority of cases it is not readily detected, and more especially 

 if the first or main phase (i. e. outer surface negative) is very large. 

 Often this second phase is only seen as an arrest of the first phase, 

 or perhaps as a temporary diminution in its velocity, so that the first 

 phase of the variation takes place in two stages. But it is only when 

 the first deflection is very large in amount, that the second phase 

 shows itself in this equivocal manner. 



These facts point to the conclusion that the differences of poten- 

 tial caused by excitation of the chorda lead to the production of a 

 cli-phasic current the first phase of which, being generally much the 

 larger, obscures to a greater or less degree the second and smaller phase. 



We will now consider the first or main phase (i. e. outer surface 

 of gland becoming negative to the hilus) more in detail. Its latent 

 period is very short, and when the variations are observed on the 

 galvanometer scale, it gives one the idea of immediately following the 

 excitation ; but by photographing the variation by means of a capillary 

 electrometer it was found as the mean oi a few observations to be 

 about 0,37" in length. 



The deflection (when the chorda is stimulated for a short time 

 e. g. 10") quickly reaches its maximum and then declines more slowly. 



