236 



THE PRINCIPLES OP AGRICULTURE 



404a. In connection with intestinal digestion and absorption, 

 the bile fills a specially important economic function, in sup- 

 plying many of its ingredients to be used over and over again 

 in the course of the same day. The bile stimulates in a high 

 degree the absorption of the digested products, entering with 

 them into the veins. As all the blood returning from the 

 intestines must pass through the liver, the elements of the 

 absorbed bile are secreted anew and once more poured into the 

 intestine. Hence a small amount of bile performs a very large 

 amount of work ; and hence, too, any suspension of the secre- 

 tion of bile interferes seriously with the general health. 



409a. A ptomaine (pronounced to-main) is a material formed 

 from the decomposition of dead tissue. It is alkaline, and often 

 poisonous. The poison in unwholesome ice-cream, for example, 

 is a ptomaine. Ptomaines often result from the destructive 

 work of microbes. The term toxin is applied to a poisonous 

 product of fermentation, whether alkaline or neutral. 



4096. It may be well to speak of the destination of the 

 chyle. Chyle is the liquid formed of the materials absorbed 



from the bowels into the 

 lymph vessels. It is albu- 

 minous (nitrogenous) and 

 fatty, with a white, milky 

 color. This, like the lymph 

 in the other lymph vessels 

 in various parts of the 

 body, contains white, 

 spherical, microscopic 

 cells, which are greatly 

 increased after passing 

 through the lymph glands, 

 and when poured into the 

 blood become white blood 

 globules. During the in- 

 Fig. 89. Surface of mucous membrane of tervals in which there is 

 the intestine, showing villi with cen- no digestion, the lymph 

 tral lacteal duet and blood vessels, . . , . , 



and on the surf ace the absorbing epi- or ch y le ln these mteS - 

 thelial cells. tinal vessels, as in other 



