The electrica] phenomena accompanying secretion, 127 



Atropine in such doses (5 — 10 mgrms) as suffice to annul the 

 electrical effect produced by chorda -excitation is absolutely without 

 effect on the sympathetic -variation, this being in fact very refractory 

 to the action of the poison in moderate doses; thus again emphasizing 

 the great difference which obtains between the chorda- and sympa- 

 thetic-variations. In large doses (40 mgrms to 100 mgrms) however, 

 atropine is not without effect. At first it produces great lengthening 

 of the latent period, and then if the dose is increased, e. g. to 00 mgrms, 

 not only is the latent period prolonged but the amplitude of the va- 

 riation is steadily diminished, though often, even after 100 mgrms, a 

 slight variation (i.e. 10 — 15 divisions of the scale) is still distinctly 

 perceptible, at least when the sympathetic is excited by strong stimuli. 

 Thus although at first sight atropine does not appear to annul the 

 sympathetic -variation, yet in very large doses, i. e. 100 mgrms, it 

 practically does so, as the small effect mentioned is only observed with 

 the strongest stimuli, and presumably would also be abolished if the 

 dose were still further increased. 



Cat. — As is well known excitation of the chorda and sympa- 

 thetic in the cat causes effects very different from those which it pro- 

 duces in the dog and we hoped by investigating the electrical pheno- 

 mena in the former to get some light thrown upon the question, 

 whether the character of the electrical variation depends upon the 

 nature of the secretion. We have in fact obtained results, which 

 although they do not enable us to state categorically that the sign 

 of the variation is dependent upon the chemical nature of the secretion, 

 yet point strongly in that direction. 



Chorda- variation. As in the case of the dog so in the cat, exci- 

 tation of the chorda tympani 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 far 

 more frequently present, and very often is greater in amount than the 

 first. Furthermore in a few cases the first phase (outer surface nega- 

 tive) was very small indeed (e. g. less than 20 galvanometer -scale 

 divisions) and in one case it was absent throughout the whole experi- 



