Tlie Heart of the Snake. 493 



may give rise only to acceleration, or acceleration followed 

 by slowing, when a stronger current caused only decided 

 and prompt inhibition. In such cases the result has followed 

 stimulation of various parts of the body. Similar obser- 

 vations have been made in the Sea-Turtle 1 on stimulation of 

 the surface of the liver. In these cases the nerve mechanism 

 requisite for reflex inhibition was intact, and the brain 

 beyond the medulla destroyed. As the above has been an 

 almost constant result of excitation by the interrupted cur- 

 rent of the anus, and above all of the tail in the Fish, it is 

 not possible to explain it in this animal by escape of current 

 on either the main stems or terminal branches of the vagi. 

 ISTor do I think this explanation holds for either the Sea- 

 Turtle, or the Snake. The subject has been discussed in 

 my paper on the Alligator. 2 Our knowledge does not seem 

 to be sufficient at present to clear up these cases fully ; in 

 the meantime, I add the results in the Snake to those 

 already recorded for other cold-blooded animals. 



In the explanation of Marshall Hall's remarkable result" 

 on crushing the stomach of the Eel, when cardiac inhibition 

 followed, notwithstanding that the brain and spinal cord 

 had been wholly destroyed, McWilliam 3 holds that Hall's 

 explanation of exhibitory action through the sympathetic 

 system is not valid, and that the result is to be explained 

 by vibratory stimulation of the vagi, owing to the concus- 

 sion of the blow of the hammer used in crushing the 

 stomach. 



With a view of testing the above hypothesis as regards 

 the Snake, in a case in which reflex inhibition was specially 

 well marked, I destroyed the whole brain and then attempted 

 to get cardiac arrest by blows upon the animal with a large 

 forceps, and heavy blows on the table on which the subject 

 of the experiment rested, but with entirely negative results. 

 That in the sensitive heart of the fish McWilliam's explana- 

 tion might, in certain cases, be valid, it is possible to under- 

 stand ; but that they explain either Marshall Hall's experi- 



1 Op. Cit. p. 7. 



2 Journal of Anat. and Phys., Vol. xx., p. 555 et seq. 



3 Op. cit., p. 238. 



