BLOOD-CORPUSCLES IN HIGH ALTITUDES 231 



Pembrey and Allen, moreover, have abolished Cheyne-Stokes re- 

 spiration by increasing the amount of C0 2 in the air breathed. 

 In high altitudes the C0 2 in the air is less, and this together 

 with the increased pulmonary ventilation produced by oxygen- 

 hunger lowers the alveolar C0 2 tension. The respiratory centre 

 thus lacks its normal excitant. The C0 2 in the venous blood, 

 moreover, under ordinary conditions, raises the oxygen tension by 

 increasing the dissociation of OHb. This enables the tissues to 

 obtain most of the 2 in the blood in dyspnoeic conditions, 

 produced by stenosis of air- passages, &c. (Bohr). Such action of 

 the C0 2 is prevented by the increased ventilation. Mosso has 

 wrongly regarded the lessened C0 2 tension as the primary cause 

 of mountain sickness. 



THE BLOOD-CORPUSCLES IN HIGH ALTITUDES 



Bert, having reached the conclusion that anoxysemia is the 

 cause of mountain sickness, was confirmed in this view by the 

 observation that animals living in Mexico at 3700 m. had double 

 the normal number of red corpuscles. Viault found 6-5-9 million 

 corpuscles per c.mm. in Peruvians dwelling at 4392 m. In the 

 lama he found 16 million. These results have been frequently 

 confirmed and ascribed to many causes to increased formation, 

 to increased drying and concentration of the blood, to congestion 

 of the blood in the peripheral parts and increased concentration 

 there, and lastly, to changes induced on the blood-counting 

 chamber by the alteration in barometric pressure. This last 

 explanation has been negatived by exact measurements, and there 

 can be no doubt that the change actually occurs. The change may 

 occur in balloon ascents in less than an hour, and is to be ascribed 

 to the increased transudation of lymph out of the peripheral 

 vessels, which leads to a concentration of the blood in these parts. 

 Foa has found 3 million more corpuscles in the blood taken from 

 the vein of the ear than in that from the carotid of rabbits kept 

 on Monte Rosa. 



In animals kept at low pressures for ten days or so, there 

 occurs an actual increase in the number of red corpuscles pro- 

 duced by an increase in the heemotopoietic activity of the 

 bone marrow. The amount of iron in the blood increases, while 



