THE GASEOUS EXCRETION. 389 



however, are not in good agreement. For 1.6 square meters 

 of skin surface the results found in seven observations varied 

 from 2.2 gm. to 32 gm. in 24 hours. The last result is prob- 

 ably much too high. It has been noticed further that the 

 amount of carbon dioxide escaping through the skin is in- 

 creased greatly by temperature. The excretion at 30 seems 

 to be several times as great as at 20. 



For the absorption of oxygen no exact figures are given, but 

 the amount is very small. In some of the lower animals, how- 

 ever, a large part of the absorbed 'oxygen, as well as of the 

 excluded carbon dioxide, may be by way of the skin. This 

 has been shown especially in the frog, where after removal of 

 the lungs a nearly normal exchange may be noted for a period 

 of days. 



The question of the excretion of other gases than carbon 

 dioxide by the skin, and the lungs also, has been much dis- 

 cussed. Formerly it was held that a very appreciable quan- 

 tity of organic gaseous bodies is given off through the skin 

 and this elimination was considered necessary for the well 

 being of the body. The unpleasant odor of the air of a 

 crowded room was ascribed to these organic emanations. But 

 much doubt has been thrown on this notion by various experi- 

 ments, some of which are of very recent date, which seem to 

 show that these odors come not through the skin but from 

 decaying substances on the surface of the skin or from the 

 clothing, if it is old and soiled. Experiments have been made 

 of testing the air drawn through a small respiration chamber, 

 enclosing the body of a man to the neck, with perfectly clean 

 skin and clothed in fresh, clean garments. Such air is prac- 

 tically without odor and has no action on solutions of perman- 

 ganate through which it is aspirated. It is free from ammo- 

 nia. The odors of perspiration are apparently largely due to 

 the fermentation changes of solid or semi-solid substances on 

 the surface of the skin rather than to excreted gaseous prod- 

 ucts passing through the pores with the water. It has been 

 found also that the whole surface of the body may be covered 



