The electrical phenomena accompanying secretion, i;;;; 



extremely small amount. Thus in one case 2 mgrms of atropine abo- 

 lished the first phase of the sympathetic-variation, leaving only the 

 second phase, ami a further injection of 8 mgrms abolished also this 

 second effect, so that a dose of 10 mgrms of atropine was sufficient 

 to completely abolish all electrical effect. When however a large se- 

 cond phase is present, as much as 40 mgrms may be necessary to 

 completely abolish it, but even this dose is far less than that usually 

 required in the dog. 



Electrical phenomena in the parotid of the dog. 



As yet only a few experiments have been made by us upon the 

 parotid, but they are sufficient to show that here the process of se- 

 cretion is accompanied by electrical changes similar to those occurring 

 in the submaxillary. The parotid is not so easily investigated as the 

 submaxillary, since it is more difficult to lead off from it satisfactorily 

 and the secretory nerve is less easily got at for excitation. In our 

 experiments, one electrode was placed as close as possible to the point 

 where the duct leaves the gland, and the second either on the surface 

 of the gland at some distance from the first, or touching the posterior 

 border of the gland on its deep aspect. 



The current of rest is apparently much less is amount than in 

 the submaxillary ; this however may well be due to differences in the 

 leading off. Its sign appears variable, but from the small number 

 of observations as yet made it is impossible to speak definitely on 

 this point. 



On excitation of the tympanic plexus well marked differences of 

 potential are produced showing that the portion of the gland near the 

 duct has become positive to the rest of the surface, a result similar 

 to that described in the submaxillary. This variation is abolished by 

 small doses of atropine (5 — 10 mgrms) and a small second phase may 

 be detected after the initial action of the drug. 



Sympathetic stimulation produces a variation of a sign opposite 

 to that obtained by excitation of the tympanic plexus, and this, like 

 the corresponding effect in the submaxillary, is very refractory to 

 atropine. 



