1886.] Secretion in the Salivary Glands of the Dog and Cat. 205 



frequently after such a dose of atropine the second phase {i.e., outer 

 surface of gland positive to hilus) is seen on excitation of the chorda, 

 although previously not detected, owing to the magnitude and 

 rapidity of the deflection caused by the first or main phase. 



This second phase is more refractory towards atropine than the 

 main phase, although ultimately abolished by it in large doses. 



Excitation of Sympathetic causes well-marked changes of potential in 

 the gland structures which are very different to those produced on 

 excitation of the chorda ; the latter have a very short latent period, are 

 readily abolished by atropine, and are of such a sign as to cause the 

 outer surface of the gland to become negative, occasionally followed by 

 the outer surface becoming positive. 



Excitation of the sympathetic, however, produces after a very long 

 latent period an electrical effect very refractory as regards the action 

 of atropine on it, and of such a sign that the outer surface of the 

 gland becomes positive to the hilus. 



Further, the course of the variation is very Tslow, and its amplitude 

 is much less than that of the chorda variation. Thus in one case on 

 excitation of the sympathetic a deflection of 62 was obtained, the 

 chorda giving a deflection of 140 with shunt. 



Atropine in small doses has apparently no effect on the sympathetic 

 variation, but in large doses, 40 — 100 mgrms., it is not without effect, 

 at first producing great lengthening of the latent period, and then 

 steadily diminishing the amplitude of the variation, although after 

 even 100 mgrms. a slight variation, i.e., 10 — 15 divisions, is still per- 

 ceptible. 



Cat. Chorda tympani. — In the cat, excitation of the chorda causes 

 an electrical variation of such a sign that the outer surface of the 

 gland becomes negative to the hilus, but whereas in the dog, a second 

 phase was on the whole not observed in the majority of cases, in the 

 cat a second phase is usually present, and very frequently is greater 

 in amount than the first phase. Further, in a few cases, the first 

 phase {i.e., outer surface of gland negative) was very small indeed, 

 i.e., less than 20 divisions, and in one case it was absent, the chorda 

 giving a pure second phase. These varieties observed in the varia- 

 tions are largely dependent on the nature of the accompanying 

 secretion. 



In these cases in which the first phase was large, the secretion was 

 very watery, and if the secretion obtained was viscid the electrical 

 variation consisted of a small first phase and a large second phase. 



Atropine in doses of 2 — 20 mgrms. abolishes the first phase of the 

 chorda variation, leaving the second phase, as in the dog, and this 

 second phase requires a larger dose to abolish it, i.e., 20 — 40 mgrms. 



Excitation of the sympathetic in the cat produces an electrical 

 effect resembling more the chorda effect of the cat than the sympa- 



