liebig's organic chemistry. 
189 
surrounding air. The habits and manners of different na- 
tions also afford proof to the same effect. In civilized na- 
tions the loss of heat is prevented by the use of clothing, not 
allowing ready escape for caloric, but in many barbarous na- 
tions no such protection is used, and this with the active^ 
exertions of hunting, requiring a greater amount of caloric, 
they are able and do consume a proportionally greater 
amount of food, and that also of an animal nature. In starva- 
tion, and in hybernating animals, the organs themselves supply 
the matter to be consumed, and which is not replaced by 
the nutritive process. All the oxygen which enters the 
system daily, is given out again in combination with part 
of the body; and death results with greater or less rapidity, 
in proportion to the bulk of the individual, the exertion 
used, and the temperature of the surrounding medium. 
These observations lead to very important and interest- 
ing views, as to the operation of external agents in health 
and disease, of which our space will not permit the notice. 
In the nutritive process, it must be conceded, that the 
blood is the all-important agent in supplying the means of 
increase, development, and waste. It is, then, to the com- 
position and ingredients of this fluid that we must look to 
determine what substances are nutritious, or capable of con- 
version into blood. 
The mostimportant ingredients of thisfluid are albamenand 
fibrine. Chemical analysis of these bodies leads to the remark- 
able fact, that they are identical in composition; containing, 
notwithstanding their dissimilar physical properties, the same 
elements, and in the same proportion. They also agree in some 
of their chemical reactions, and fibrine has even been con- 
verted into albumen by chemical agents. From this iden- 
tity, there is no difficulty in conceiving the conversion of 
blood into muscular fibre, and muscular fibre into blood. 
All the other parts of the animal structure contain the same 
elements which are to be found in blood. They all contain 
17* 
