200 QUARTERLY JOURNAL. 



the proportions to form water, the hydrogen being in excess. This 

 principle is destined to combine with the oxygen introduced by re- 

 spiration into the blood, and by the combustion of its carbon and ' 

 hydrogen to generate heat. When there is not enough of oxygen 

 introduced to burn up all the fat of the food, this principle accu- 

 mulates in the cellular tissue. 



3. The saccharine principle, including sugar, gum, starch, and 

 all those substances composed of carbon, combined with oxygen 

 and hydrogen in the proportion to form water. The use of this 

 principle is nearly the same as that of the oleaginous ; it serves for 

 generating animal heat, but in a less degree, for it contains less 

 carbon, and the other two elements are in such proportions as to 

 have satisfied their affinities, and no surplus hydrogen remains to 

 be burned. The saccharine principle undergoes conversion into 

 fat, when there is a deficiency of oxygen for its combustion. 



Let us now apply these principles to determining the propor- 

 tions in which these principles should be combined, in the food oi 

 man and of animals under different circumstances. 



Tn proportion as the waste of the tissues is greater in nutrition 

 will a larger supply of the albuminous principle be required in th( 

 food to replace the fibrin abstracted from the blood. Muscula) 

 exercise contributes to an increased activity of the nutritive act 

 and thus renders a larger proportion of this principle necessary. 



In proportion as the surrounding atmosphere is colder will \h 

 body be required to generate more heat in order to preserve its uni 

 form temperature. This increased heat is generated by exercise anc 

 by proper diet. Exercise generates more heat in two ways : 1st 

 by accelerating the circulation and respiration, it introduces men 

 oxygen into the blood ; 2d, by increasing the activity of the de 

 composition of the tissues in nutrition, it liberates more carboi 

 which is burned by the oxygen. The diet of one taking activ. 

 exercise in a cold air, should contain a large portion of th' 

 albuminous principle, to replace the waste of the tissues and of th- 

 oleaginous principle to be burned by the surplus oxygen. A mai 

 or animal laboring in a cold air requires food rich in these twt. 

 principles and soon sinks under a diet composed of a large portioii 

 of the saccharine principle — such as rice, fruits, &c. A starvinj 

 man freezes if exposed to cold, and the same thing happens to . 

 man well fed but kept at rest. The former freezes because, thougli 



