NUTRITIVE FUNCTIONS DIGESTION. 283 



25. It would seem, then, that the great business of diges- 

 tion is to change the food into albuminous matter, which 

 forms the basis of the chyle as well as the blood ; and it is 

 certain that no albumen is formed in the stomach ; though 

 the change which the food there undergoes, is an approach 

 to the nature of albumen. As the bile is alkaline, it doubt- 

 less combines with, and neutralizes the acid properties of 

 the chyme, which would precipitate the mucus of the bile, 

 and leave it in a state of coagulation. 



26. Chyle then is the fluid, which is taken up by the ab- 

 sorbent vessels, called lacteals, whether it exists ready formed 

 in the chyme, or is manufactured out of it, by the action of 

 these vessels themselves. It is usually of a milk white co- 

 lour, but varies in appearance in different animals ; and ac- 

 cording to the nature of the food. In animals that feed on 

 flesh, it is opaque ; in such as live on vegetables, it is trans- 

 parent ; in birds and fishes, thin, serous, and clear like wa- 

 ter. It is saltish, and somewhat sweet to the taste ; heavier 

 than water but less so than blood. It coagulates on stand- 

 ing, like blood, and separates into three portions ; a fluid, a 

 coagulum, and a fatty substance. The fluid portion is chief- 

 ly of albumen and coagulates like the serum of the blood by 

 heat, acids, and alcohol ; the coagulum consists of fibrin, 

 and a coloring matter, which is white. 



27. Whatever the food may consist of, physiologists are 

 now pretty well agreed, that the chyle will always be com- 

 posed of Jlbrin, albumen, a fat matter, muriate of soda, and 

 phosphate of lime, though in variable proportions. Food 

 that contains much azote, such as that of animals, it is sup- 

 posed will form chyle, which contains a greater portion of 



Jibrin than that of vegetables, as azote is one of the chief ele- 

 ments of fibrin. Dr. Marcet states that chyle produced from 

 vegetable aliments contains three times as much carbon as 

 that formed out of animal substances. It is certain that 

 chyle from animal food is milky ; and that from vegetables 

 transparent. As both however are composed of the same 



