230 



DIGESTION. 



[CHAP. xxv. 



Fig. 162. 



The function of the villi appears evidently to be connected with 

 absorption, and specially witb the absorption of chyle. This view 



rests upon the following 

 grounds: First, that the 

 villi exist only in the small 

 intestine, where the most 

 active absorption of di- 

 gested matters evidently 

 goes on; and that they 

 are most highly developed 

 and most numerous in 

 that part of the small 

 intestine where chyle is 

 first formed. Secondly, 

 that during the process 

 of chylification the villi 

 are turgid with blood, 

 and obviously present all 

 the appearance of being 

 the seat of some active 

 vital process; they are 

 enlarged and opaque, ap- 



Vertical section of the coats of the small intestine of a L\ f 1, 



dog, showing only the commencing portions of the portal vein parently IrOm a CnangC 



and the capillaries. The injection has been thrown into the ,1 , -11 



portal vein, but has not penetrated to the arteries, a. Vessels in the llltraVlllOUS tlSSUB, 



T ' e and probably also from 



the introduction of some 

 new matter into them. In 

 animals that have been 

 kept fasting for some 

 time prior to death the 

 villi look small, and as 

 if shrunken within their 

 epithelial sheaths, which, 

 in some instances, adapt 

 themselves to the dimi- 



A. Epithelium detached, and free in the cavity of the duo- . , , . , , 

 denum, taken, immediately after death, from a dog fed 2 hours niSned. S1Z6 Ol the Cn- 

 before. Each cell is filled with apparently fatty matter, partly , -, .-,-,. i -i 



granular and partly in globules. Magnified 600 diameters. ClOSCd Vllll, Dy becoming 



B. The same, suffered to stay an hour or two under the mi- , L f 1J /f?' 

 croscope, shewing the fatty material aggregated into larger thrown intO lOlQS. V-Flg- 

 globules, the rest of the cell-structure having become indistinct, -i KQ\ "R f 1 ' fTi 



digestive process the villi are large and full ; the nuclei of their 

 proper tissue are very distinct ; the basement membrane is here 

 and there bulged by them on the surface, especially towards the 



Fig. 163. 



B. 



