OXYGEN. 



437 



cations of a diminution in the number of red corpuscles. There is abso- 

 lutely no doubt that after staying at a mountain height for some time, an 

 acclimatization takes place in the sense that a new formation of hemo- 

 globin results. It remains undecided how much this is due to an abso- 

 lute increase in the number of red corpuscles, and how much to a merely 

 relative increase. It seems reasonable to believe that this may be brought 

 about by the adjustment of the vascular tonicity to definite pressures 

 of the atmosphere. 1 



It remains for us to decide whether, besides the lungs, other organs of 

 the body take part in the gas-exchange. We have already seen that with 

 Amphibia respiration on the part of the skin plays quite an important part. 

 In higher vertebrates this cutaneous respiration does not seem to be 

 hardly worth considering. Schierbeck 2 estimated that in man there is 

 an elimination of carbon dioxide amounting to 9 grams per 24 hours, 

 or somewhat less than 1 per cent of the total gas-exchange. If there 

 is an increased secretion of sweat, it may rise as high as 30 grams in 

 24 hours. The absorption of oxygen is much less. The following table 

 prepared by Krogh 3 gives a good idea as to the extent of this cutaneous 

 respiration on the part of man and certain animals : 



The above values refer to the amount per hour and per square decimeter 

 of the skin. The volumes of the gas are given in cubic centimeters. 



It was for a long time believed that the skin took part in the elimination 

 of the gaseous products of metabolism. It had been observed, for example, 

 that if the skin of an animal were varnished over it soon died. This, 

 however, has more recently been found to be caused not so much by the 

 retention of waste gases, as by the greatly increased amount of heat, 

 caused by the crippling of the means for regulating the body tempera- 



1 Mountain sickness has been attributed to various causes, one of which is undoubt- 

 edly a faulty regulation of the vascular tone. 



2 Arch. Anat. Physiol. 1893, 116. Cf. Aubert: Pfliiger's Arch. 6, 539 (1872). 



3 Skand. Arch. Physiol. 16, 378 (1904). 



