CHAPTER XV. 



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 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. There is complete 

 evidence of Expenditure by the living body. 



From the table (p. 208) it will be seen how the various amounts of 

 the excreta are calculated. 



a. From the Lungs there is exhaled every 24 hours, 



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



Of Water, 5,000 " 



Traces of organic matter. 



b. From the Skin 



Water, 11,500 grains. 



Solid and gaseous matter, . . . 250 " 



c. From the Kidneyi 



Water, 23,000 grains. 



Organic matter, 680 " 



Minerals and salines, .... 420 " 



d. 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. 



Altogether, the expenditure of the body represented by the sum of 

 these various excretory products amounts every 24 hours to 



