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animals there is at first powerful vagus action, and the 

 auricular beats soon become so weakened that the ventricles 

 take on their own independent rhythm. It cannot in the 

 meantime be proved that this causes the subjective feeling 

 of palpitation of the heart, and it can only be said that the 

 independent ventricular contractions show themselves under 

 conditions similar to those which produce the feeling of 

 palpitation of the heart, and that the latter is just the kind 

 of feeling one would expect when the heart changes its 

 mode of contraction in this particular way. In asphyxia as 

 produced in animals there is a very great dilatation of the 

 ventricular walls although the strain upon them (measured 

 by the amount of blood pumped out phis the pressure in 

 the aorta and pulmonary arteries) may not have been in- 

 creased. This yielding of the ventricular wall is almost 

 certainly due to the diminution in amount of oxygen in the 

 blood circulating in the coronary arteries (4). 



This weakening of the heart brings the vagus mechanism 

 into increased activity, the effect of which on the heart is 

 to economise its action ; and palpitation, if I am right about 

 its nature, is under the circumstances an indication that the 

 heart is distressed. 



To the cardiac dilatation due to asphyxia is added the 

 dilatation which is caused by muscular exertion ; the two 

 together will lead to heart-failure more readily than either 

 of them singly ; by heart-failure being understood the 

 condition in which from its over dilatation the tricuspid 

 orifice can be no longer closed by the tricuspid valve. 



There is no doubt that heart-failure is of not uncommon 

 occurrence even in the Alps (5), and that when it occurs 

 the person suffering from it is practically incapacitated from 

 further climbing owing to intense dyspnoea, palpitation, and 

 irregularity of the heart. Guides, who know the condition 

 perfectly well in their own cases, or in that of their " Her- 

 ren," have told me that when badly taken with it near the 

 top of a mountain, the only way to get the person up the 

 last 100 feet or so, is to practically carry him up. The 

 incapacity for further exertion is certainly very great, as I 

 happen to know, but a quarter or half an hour's rest 



