496 Canadian Record of Science. 



suits as to a really independant rhythm, and confirm views 

 already expressed in the other papers in which my work 

 has been recorded. 



Summaky. 



1. The investigations recorded in this paper were made 

 in midwinter, on fasting but not hibernating animals. 



2. Comparison of the vagi showed that in every instance 

 both nerves were efficient ; but usually the right was the 

 most so; in some cases the difference, if actual, was 

 minimal. 



3. Stimulation of the vagi, leads to after increased force 

 and frequency of beat, or of the former only, and accord- 

 ing to the law 1 of inverse proportion previously announced 

 by the writer. 



4 The mode of arrest of the heart is identical with that 

 noted in the Chelonians, Fish, &c. ; the same applies to the 

 mode of re-commencement. 



5. During vagus arrest the sinus and auricles are inex- 

 citable. 



6. There are certain peculiar cardiac effects not expli- 

 cable by reference to the vagi nerves alone, but which put 

 the sj^mpathetic system of nerves in a new light. 



7. Direct stimulation of the heart confirms results pre- 

 viously noted by the writer for other cold-blooded animals. 

 Arrest is, in all the animals of this class yet examined, 

 owing to stimulation of the terminals of the vagi within 

 the heart's substance. 



8. As regards independent cardiac rhythm, the results 

 have been negative. 



9. The heart of the Snake, upon the whole, seems to lie 

 physiologically between that of the Frog and that of the 

 Chelonians. 



Physiological Laboratory, 



McGlLL TJUIVERSITY, 



Montreal, June, 1887. 

 1 Journal of Phys., Vol vi., p. 281 et seq. 



