CHAPTER XVII. 



NUTRITION; THE INCOME AND EXPENDITURE OF THE HUMAN 



BODY. 



THE various physiological processes which occur in the human body 

 have, with the exception of those in the nervous and generative systems, 

 which will be considered in succeeding chapters, now been dealt with, 

 and it will be as well to give in this chapter on Nutrition a summary of 

 what has been considered more at length before. 



The subject may be considered under the following heads. (1). The 

 Evidence and Amount of Expenditure. (2). The Sources and Amount 

 of Income. (3). The Sources and Objects of Expenditure. 



1. Evidence and Amount of Expenditure. The evidence of 

 Expenditure by the living body is abundantly complete. 



From the table (p. 212, Vol. I.) it will be seen how the various amounts 

 of the excreta are calculated. 



From the Lungs there is exhaled every 24 hours, 



Of Carbonic Acid, about .... 15,000 grains 



" Water 5,000 " 



Traces of organic matter. 



From the Skin 



Water 11,500 grains 



Solid and gaseous matter .... 250 " 



From the Kidneys 



Water 23,000 grains 



Organic matter ...... 680 



Minerals or salines 420 " 



From the Intestines 



Water 2,000 grains 



Various organic and mineral substances . 800 " 



In the account of Expenditure, must be remembered in addition the 

 milk (during the period of suckling), and the products of secretion from 

 the generative organs (ova, menstrual blood, semen); but, from their 

 variable and uncertain amounts, these cannot be reckoned with the pre- 

 ceding. 



