180 PHYSIOLOGY. 



supply the animal fluid. This, however, as we have already 

 said, is seemingly, together with water, the foundation of all 

 other fluids in animal bodies ; and, particularly, that from which 

 the nutritious matter applied to the increase of the solid parts, 

 is, by the powers of the economy, formed and prepared. It is 

 this animal fluid, therefore, that our vegetable food is to be con- 

 verted into ; and it seems to be a matter formed not from any 

 one kind, but, by the powers of the animal economy, from vari- 

 ous kinds of vegetable matter. Accordingly, when we are to 

 say that certain parts of vegetables are alimentary, we mean 

 only to say that they are matters fitted to enter into the com- 

 position of the proper animal fluid." M. M. 



CCXII. The oily matter of vegetables, which makes part of 

 the aliment of animals, is without any sensible odour or taste, 

 and is not only very nearly the same in the many different veg- 

 etables from which we take it, but is also in all of these so nearly 

 akin to the oil which appears in animals, that it is not necessary 

 to suppose any considerable change to be made upon the vege- 

 table oil on its being taken into the bodies of animals. 



" Here, however, it may be imagined, that oil enters into the 

 composition of the animal fluid only as it is a part of farina, or 

 as it happens to be mixed by nature with other vegetable mat- 

 ter ; and that, as it is taken in, whether from animals or vege- 

 tables in a separate state, it affords only the oily matter that is 

 necessary to be constantly present in considerable quantity in 

 the bodies of animals, not for their nourishment, but for certain 

 other purposes of their economy. 



" We cannot, however, enter into this opinion : for we are 

 persuaded that even the oil which is taken into the body in the 

 form of a pure oil, though entirely separate from other vege- 

 table matter, does truly, in a large proportion, enter into the 

 composition of the animal fluid ; and that oil, therefore, may 

 be considered, in the strictest sense, as a fundamental part of the 

 human aliment. 



" We are of this persuasion, how much soever neglected by 

 physiologists, from the following considerations : 



" 1st, We observe that oil, both from vegetable and animal 

 substances, is daily taken in as part of diet by the people of all 

 nations, and often in large quantity, without increasing obesity. 



