MOUNTAIN SICKNESS. 91 



generally makes the person feel all right again, recovery 

 beginning to take place in ten minutes or so, although at 

 first, sitting down gives no relief to the distress. I must 

 return to this subject later. 



1 now come to the other symptoms of mountain sickness, 

 and have to consider how far they can be looked upon as 

 due to asphyxia. The headache, with a sense of fulness, as 

 if a tight band were drawn round the head, may be safely 

 put down to cerebral congestion, and the haemorrhages from 

 the nose and conjunctiva agree with the known fact that 

 the blood supply of the latter usually goes with that of the 

 brain. Cerebral congestion is a constant result of asphyxia (7). 

 The giddiness, nausea, vomiting, blurring of the sight, and 

 the indifference to danger, somnolence, and perhaps also 

 the excitability, are all, I imagine, caused by the diminished 

 supply of oxygen to the brain, which is perfectly compatible 

 with congestion of that organ if the tension of the oxygen 

 in the blood be reduced. The nausea and vomiting are of 

 cerebral origin, for they do not cease with evacuation of the 

 stomach, although they may follow the ingestion of food, 

 and may become more marked as a result of indigestion. 

 The lessened appetite and diminished power of digestion 

 are presumably due to the anaemia of the digestive tract, 

 which are invariably produced by asphyxia, according to 

 observations by L. Cobbett and myself, which are as yet 

 unpublished. The singing in the ears may be due in part 

 to difference in pressure of the air within and without the 

 tympanic membrane, the Eustachian tube not completely 

 fulfilling its function in this respect. 



The muscular weakness I have already referred to as due 

 to the imperfect supply of oxygen to the muscles. The 

 ready cooling of the extremities which prevented Conway's 

 party from moving by moonlight at high altitudes I am 

 inclined to put down to the diminished heat production, 

 which results from the imperfect supply of oxygen to the 

 muscles, which are the chief sources of heat in the body, 

 and which may be aided by congestion of the skin increasing 

 the amount of heat given off by it. 



So far as the symptoms are concerned, we need therefore 



