148 THE D AIR YM ax's MAXUAL. 



dissolved and changed to sugar,. and the oilj part of the 

 food has been worked up by the mastication and tritura- 

 tion in the stomachs into an emulsion with the other 

 constituents of the food. In tlie bowels, the food is 

 subjected to the action of the bile which is poured out 

 from the liver, and the fluid of the pancreas, the ofiBce 

 of which is not yet clearly established. The changes ' 

 which are effected in the intestines are the complete 

 conversion of any remaining starch into sugar ; the 

 albuminoid substances are brought into the condition 

 of soluble albumen, and the fats are still further divided 

 and made into a more j^erfect emulsion. 



Digestion is then completed. The food is brought 

 into contact with the absorbent vessels of the mucous 

 membrane of the intestines, and the process of assimila- 

 tion begins. The dissolved food and the emulsified fat 

 are then absorbed by the very small capillary blood 

 vessels of the mucous membrane of the stomach and in- 

 testines, and pass on with the venous blood into the liver 

 and lungs, where it is purified by the combustion of the 

 excess of carbon by which the animal heat is sustained, 

 and the purified fluid is poured into the heart and mixed 

 with the arterial blood; thence carried to every extremity 

 of the system it repairs the waste and adds new matter 

 to the growing animal. 



The fat, in the form of an emulsion or exceedingly 

 intimate mixture, in particles so fine as to be invisible, is 

 absorbed directly into the circulation and is carried on 

 with the blood to be deposited where the exigencies of 

 the system require it. It is deposited in the tissues, or 

 in masses in various parts of the bod}^ and in females, at 

 and after the birth of their young, is carried in large 

 part to the udder, where it is first deposited in the gland- 

 ular cells of the udder, and is then mingled with the 

 copious secretion known as milk. 



Thus the milk of the cow is a direct product of the 



