SUPPORTED BY STARCH, SUGAR, ETC. 143 



pected from the identity of its composition with that 

 of starch; it also consisting of carbon, with hydrogen 

 and oxygen in the proportions to form water. Sugar, 

 when not taken in too large quantities, must be con- 

 sidered a wholesome food, particularly as supplying 

 material for keeping up the heat of the body. Some 

 authors have condemned it, because animals would 

 not thrive on it alone; but this is no argument at all. 

 The same result would follow feeding upon any other 

 single article, to the exclusion of all others. The 

 animal requires and must have a mixed food, or it 

 will not thrive. 



b. Fatty and oily substances have the same function 

 to perform; they also consist of carbon, hydrogen, 

 and oxygen, and, in animals that do not eat ve- 

 getables, are undoubtedly the chief source by which 

 carbon is supplied to the lungs. When food fails, fat 

 from various parts of the body is first used to support 

 respiration : hence results the remarkable emaciation 

 which appears after long abstinence, or during star- 

 vation. 



Fat is extremely useful in the body for various pur- 

 poses. It lubricates and smooths the joints, the mus- 

 cles, and the tendons, so that they play easily and freely; 

 it fills up hollows, making the body plump and rounded, 

 instead of angular and full of disagreeable cavities, 

 as it would otherwise be. This necessary part of the 

 animal, is chiefly derived from the oily and fatty sub- 

 stances in the food. It seems clear that, under certain 

 circumstances, both starch and sugar may and do pro- 

 duce fat. This is partially the case when the food con- 

 sists entirely of potatoes, or when it is nothing but 

 apples. Still we see that those varieties of food which 

 contain most oil, fatten animals quickest. 



a. Indian corn is an instance of this : linseed cakf 

 is a still more striking one. Such food not only sup- 

 plies the usual daily waste of the body, but causes 

 an accumulation and increase of fat The natural 



