CHAPTER XX. , 



THE INCOME AND EXPENDITURE OF THE BODY. 



The Material Losses of the Body. All day long while 

 life lasts each of us is losing something from his Body. The 

 air breathed into the lungs becomes in them laden with 

 carbon dioxide and water vapor, which are carried off with 

 it when it is expired. The skin is as constantly giving off 

 moisture, the total quantity in twenty-four hours being con- 

 siderable, even when the amount passed out at any one time 

 is so small as to be evaporated at once and so does not collect 

 as drops of visible perspiration. The kidneys again are con- 

 stantly at work separating water and certain crystalline ni- 

 trogeneous bodies from the blood, along with some mineral 

 salts. The product of kidney activity, however, not being 

 forthwith carried to the surface but to a reservoir, in which 

 it accumulates and which is only emptied at intervals, the ac- 

 tivity of those organs appears at first sight intermittent. If to> 

 these losses we add certain other waste substances passed into- 

 the alimentary canal and got rid of along with the undigested 

 residue of the food, and the loss of hairs and of dried cells 

 from the surface of the skin, it is clear that the total amount 

 of matter daily removed from the Body is considerable. The 

 actual quantity varies with the individual, with the work 

 done, and with the nature of the food eaten; but the follow- 

 ing table (p. 300) gives approximately that of the more im- 

 portant daily material losses of an average man. 



The living Body thus loses daily in round numbers 4 kilo- 

 grams of matter (9 Ibs.) and, since it is unable to create new 

 matter, this loss must be compensated for from the exterior 

 or the tissues would soon dwindle away altogether; or at least 

 until they were so impaired that life came to an end. After 

 death the losses would be of a different kind, and their quan- 

 tity much more dependent upon surrounding conditions; but 

 except under very unusual circumstances the wasting away 

 would still continue in the dead Body. Moreover, the compo- 



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