228 



SCIENCE. 



[Vol. XV. No. 375 



Table II. — Continued. 



1 Nitrogenous substances, 

 acids. The fats, of which there are many kinds, both animal 

 and vegetable, may be said to be mixtures of three typical 

 forms, — the solid variety, stearine, found in almost every 

 animal and vegetable fat; the semi-solid form, palmitin, 

 found especially in palm-oil, whence its name; and the 

 liquid, oleine, found ia olive-oil, human fat, etc. 



Carbohydrates. 



The carbohydrates contain the same chemical elements as 

 the fats, but in different proportions, and are represented by 

 sugar and starch in the vegetable, and by liver-sugar, 

 glycogen, and muscle-sugar, inosite, in the animal kingdom. 



The average composition of these three organic classes of 

 foods may be given as follows :- — 



The following table by Professor W. O. Atwater shows, 

 in the form of debit and credit account, the daily income 

 and expenditure of a man doing a moderate amount of 

 work :- 



Water. 



Water, which forms nearly two- thirds of our bodies, is so 

 important a constituent of both animals and plants, that we 

 find it in large quantities disseminated throughout their 

 structures. 



Mineral Matters. 



The mineral matters contained in both our bodies and 

 foods are present in small quantities only. 

 Dietary. 



It is fortunate that nature has provided these great varie- 

 ties of food, so that man can make a selection suitable to his 

 age, occupation, health, and other conditions of life. The 

 subject of what are the proper proportions and kindsof food 

 suitable to an economical and healthful diet covers too large 

 a field for this series of articles ; but it may be stated that 

 people generally eat more than is requisite for the mainte- 

 nance of their bodies in a state of perfect health. 



