90 NUTRITION. 



far as refers to the balance between the income and outgo of mate- 

 rial. While it is almost an impossibility to study this subject ex- 

 actly, yet an idea of the modes of expense and income may be 

 gained by consideration of data which are tolerably fixed. In con- 

 sidering the income and expenditure of the body it is always neces- 

 sary to bear in mind that all the factors are variable and the results 

 inconstant, for the income often exceeds the expense, and vice versa, 

 in life. 



What are the daily expenditures of the body? 



The more important are those by the ordinary excretory channels 

 lungs, skin, kidneys, and intestines. 



From the lungs there are exhaled every twenty-four hours 



Of carbonic acid, about 30 ounces. 



Of water 10 " 40 ounces. 



Traces of organic matter. 

 From the skin 



Water 23 



Solid and gaseous matter 1 ounce. 24 " 



From the kidneys 



Water 50 ounces. 



Organic matter 1 " 



Minerals and salines ounce. 52 " 



From the intestines 



Water 4 ounces. 



Various organic and mineral sub- 

 stances 2 " 6 " 



Total, 122 ounces. 



What are the sources of income ? 



Food and drink and oxygen are the factors of the income, and 

 may be calculated about as follows for twenty-four hours : 



Food (chemically dry) 16 ounces. 



Water (as drink and as combined with solid food) . 80 " 

 Oxygen (absorbed by lungs) 26 " 



Total, 122 ounces. 



Thus we may represent the schematic plan of income and ex- 



