492 Canadian Record of Science. 



on one species or even genus of animals to others. A survey 

 of my own series of investigations alone, will amply demon- 

 strate the desirability of such a course as I have pursued, 

 and still more so if taken in connection with the work of 

 other investigators, like McWilliam, who have followed the 

 comparative method to any degree. A great deal of labor- 

 ious work, without brilliant results, must be done, but I 

 wish to state most emphatically my conviction that it is 

 the only way by which a broad, solid and safe physiology 

 can be produced. 



Cardiac Kiel exes. 



I have noticed in the Snake, as often in the Chelonians, 

 that while the medulla oblongata is intact, the heart may be 

 very irregular, but that upon the destruction of that part, 

 the rhythm at once changes, becoming always regular and 

 often more frequent. The explanation is probably to be 

 sought in the various influences reaching the medulla and 

 passing down the vagi in an animal in an abnormal condi- 

 tion from the circumstances of the experiment. But when 

 stimuli are applied to various parts, as the skin, the viscera, 

 etc., the results are found to be very variable. Apparently 

 there are great individual differences, and not a little 

 depends on the vigour of the animal at the moment of 

 experiment. Much of what has been established for the 

 Chelonians 1 might be repeated for the Snake. 



It only remains to note a few peculiar results of special 

 interest in this connection. It sometimes happens in the 

 Prog, and rarely in the Chelonians that the first effect of 

 vagus stimulation is not slowing but acceleration of the beat 

 of the heart. This I have not witnessed in the Snake ; but, 

 on one occasion, when reflex inhibition was unusually 

 marked, on placing the electrodes over the lung, the rate 

 was accelerated for 3-4 beats. In my paper on the Fish, 2 

 it has been pointed out that a certain strength of current 



1 Journal of Phys., Vol- VI. ; Journal of Anat. and Phys., 

 Vol. XXI. 



2 Op. Cit. p. 89. 



