Tho electrical phenomena accompanying secretion. L35 



the dog, the electrical effect is also very different. There is no reason 

 to suppose any great difference in the vasomotor fibres in the two 

 cases, sufficient to account for the observed different electrical effects ; 

 besides which, even should such difference exist, we have seen that 

 the sympathetic -effect of the cat is abolished by atropine in moderate 

 doses, and sometimes even in very small doses. We may say there- 

 fore that certainly in the cat there is no evidence to show that the 

 chorda and sympathetic electrical effects are due to vasomotor changes, 

 nor is there any such evidence in the case of the chorda of the dog, 

 and reasoning partly from the facts detailed above, and partly from 

 analogy we may conclude that even for the results of sympathetic- 

 stimulation in the dog, such an interpretation would be incorrect. 



On the other hand there is a considerable amount of evidence 

 pointing to the conclusion, that the sign of the electrical disturbance 

 varies with the nature of the secretion, as measured by its amount 

 and its viscidity. As mentioned above it is frequently observed, 

 particularly in the cat, that the same gland gives now a pure first 

 phase, now a diphasic variation, or even a pure second phase. 

 These variations, at first sight so inconstant, are explained if the se- 

 cretion be observed at the same time. Further if the observed differ- 

 ences of potential are due to changes in the cells of the gland, they 

 afford a much more delicate test of the nature and activity of the 

 gland -processes, than even the amount and nature of the secretion, 

 so that we should expect a close relationship between the sign of 

 the variation and the nature of the secretion. 



This is certainly what occurs in the cat, in which whenever the 

 galvanometer showed a large first phase (i. e. outer surface negative 

 to hilus) there was a copious secretion, watery in character, and this 

 whether the chorda or the sympathetic were the nerve stimulated. On 

 the other hand when the galvanometer showed a second phase (i. e. 

 outer surface positive to hilus) the secretion was markedly less ab- 

 undant and more viscid. And if a pure first phase was observed, the 

 secretion was more abundant than if a diphasic variation was seen, 

 and this, as mentioned above, is frequently to be noticed in one 

 and the same animal, showing very strikingly a close relationship 

 between the sign of the variation and the nature of the secretion. 



