INHIBITION AND CARDIAC VAGUS 123 



say with Sherrington, " whatever they essentially may be," 

 and that they are opposed just as warming and cooling may 

 be. But what happens as regards energy when water 

 cools is known, as it is in the rise and fall of electric 

 potential. What happens to muscle energy in " inhibition " 

 we do not know, if the usual views of cardiac weakening 

 and the depressing functions of the vagus are held. A 

 complex chemical process at the end-plate must be posited, 

 and of that there seems no evidence. To call in the nervous 

 system to produce weakening toxins or the like, even by 

 intensifying cellular catabolism, appears too great an 

 assumption to make when there is a much simpler ex- 

 planation at hand. Many of the cardiograms shown as 

 proofs of cardiac inhibition seem wrongly interpreted. It 

 is, perhaps, not too presumptuous to say that their inter- 

 pretation is an extremely difficult art, and that even among 

 the most expert cardiologists there are at times great 

 differences in opinion. Having worked for months on the 

 subject with a disciple of our greatest cardiologist I shall, 

 perhaps, be pardoned for suggesting that the most eminent 

 physiologists may err in such a special branch of learning. 

 I have seen cardiograms showing the " weakening " of the 

 heart in which the amplitude of the beats was distinctly 

 increased, and the interval between them lengthened when 

 the theory of inhibition required pathological slowing and 

 decrease of amplitude. Such results undoubtedly occur in 

 extreme vagal stimulation ; but this is only what would 

 be expected on the views expressed in this place. But to 

 get better systoles and diastoles is not weakening. It is 

 also said that under vagal stimulation the conducting power 

 of the Bundle of His is " impaired." The evidence of this is 

 merely that the heart is generally slower. Such a state- 

 ment is a mere re-statement of an assertion. That the 



