ORGANS OF THE BODY. 



497 



vision made for the escape of the chyle, as Auerbach very correctly 

 remarks, and during the peristaltic action of the bowel, also, the latter fluid 

 is able on this account to give way to the pressure in many directions. 



In conclusion, we have only to state, as regards the development of the 

 small intestine, that in man the villi make their appearance in the third 

 month of intra-uterine life. They are then apparent as wart-like excres- 

 cences. Further, we would point to the fact, that the crypts of Lieberkuhn, 

 unlike the gastric tubuli, are present from the commencement as pits in 

 the mucosa, and that the follicular structure of Peyer's glands is apparent 

 .in the seventh mouth. The cells of the intestinal mucous membrane, 

 and of Lieberkiihn's follicles, contain glycogen in the fetus (Rouget). 



259. 



The mucous membrane of the colon corresponds in most essential 

 particulars with that of the small bowel, except that it is quite destitute 



Fig. 491. Tubular glands from the 

 rabbit's colon. One tube filled with 

 cells, the others sketched without 

 them. 



Fig. 492. Tubular gland from the colon of a Guinen- 

 pig. At a, a tube is seen with membrana propria 

 apparent at certain points; at fe, the contents are 

 escaping through a rent in the latter. 



of those important appendages the villi. Its substratum, also, is far poorer 

 in lymph cells than that of the smaH intestine, 

 and approaches more in character to ordinary 

 fibrous connective-tissue. 



The epithelium cons'ists of columnar cells 

 similar to those of the ileurn, but lacking pores 

 in the but slightly thickened border. Goblet 

 cells are also met with here (Schulze). 



Its muscular tunic resembles that of the 

 mucosa of the stomach ( 251), and exhibits 

 the same variety in the relative development of 

 its two layers (Schwartz, Lipsky). Imbedded 

 in it we find a great number of tubular glands, 

 the tubuli of the colon, and a variable number 

 of lymphoid follicles like those already met 

 with in the small intestine. 



The tubuli of the colon (fig. 491) are merely 

 modifications of the follicles of Lieberkuhn from 

 which they are gradually developed. 



They present themselves in the form of 

 simple undivided tubes with tolerably smooth and even walls, and a 



Fiir. 493. Tubuli from the colon 

 of the rabbit, treated with 

 caustic soda. 



