320 Canadian Record of Science. 



to the influence of the current directly on the muscle itself, 

 but indirectly through the nervous mechanisms of the heart, 

 several considerations render highly probable. 



1. The effects of the current are very like those of stimu- 

 lation of the vagus nerve itself, as illustrated above (arrest, 

 dilation, &c.) 



2. When the nutrition of the heart is impaired (and its 

 nerves have probably suffered the most), it is impossible to 

 produce the usual effects, arrest of the sinus, auricle, &c. ; 

 while at the same time it is possible to send the ventricle 

 into the peculiar inter vermiform action referred to above. 

 This and many other things I have seeD, such as the readi- 

 ness with which even the mammalian heart, long under 

 experiment, &c, goes into a similar action known as the 

 Kronecker-Schmey phenomenon, leads me to believe that 

 this latter also is to be explained, at least in some cases, 

 by peculiar qualities of the muscle rather than through 

 nerve influence ; further, in the case of the mammal, this 

 phenomenon and the intervermiform action referred to in 

 the Chelonians, are alike wholly uninfluenced by vagus 

 stimulation. 



3. Sponging over the heart, arrests it when fresh, while 

 later it may give rise only to intervermiform action in the 

 ventricle; this seems to me a very strong argument in 

 favor of nervous influence. 



4. After the free application of atropine to the Fish's 

 heart in situ, it is impossible to arrest it either by sponging 

 it over or by the application of the electrodes to the sinus ; 

 but it is possible to initiate the intervermiform action by 

 this procedure. 



V. Evolution of Function and Cardiac Death. 



In all the Chelonians, the invariable order in which the 

 different parts of the heart die is: (1) ventricle, (2) auricles 

 proper, (3) sinus extension, (4) sinus. 



I have studied this subject especially in the sea-turtle,and 

 find that invariably the right auricle outlives the left; and, 

 as has been before indicated, the right moiety of the sinus, 



