CHAPTER XIV 



THE ABSORBENT SYSTEM 



THE nutritive matter (chyle), prepared by the digestive 

 process, is still outside of the organism. How shall it 

 enter the living tissue ? 



In animals, like the 

 Infusoria and polyps, 

 whose digestive de- 

 partment is not sepa- 

 rated from the body 

 cavity, the food, as 

 soon as dissolved, min- 

 gles freely with the 

 parts it has to nourish. 

 In the higher inverte- 

 brates having an ali- 

 mentary canal, the 

 chyle passes,by simple 

 transudation, through 

 the walls of the canal 

 directly into the soft 

 tissues, as in insects, or 

 is absorbed from the 

 canal by veins in con- 

 tact with it, as in sea 

 urchins, mollusks. 

 worms, and crusta- 

 ceans, and then dis- 

 tributed through the 

 body. 



FIG. 256. Section of Injected Small Intestine of Cat: 

 a, b, mucosa; g, villi; i, their absorbent vessels; 

 h, simple follicles; c, muscularis mucosae; d, sub- 

 mucosa; e, e' , circular and longitudinal layers of 

 muscle; f, fibrous coat. All the dark lines represent 

 blood vessels filled with an injection mass. 



297 



