SMALL INTESTINE. 



209 



tral lymphatic, within which they break down and set free the fat, but 

 this explanation of the transfer is not beyond question. It is well 



/ 



* I: 



-i, ' :^ , f M^> 



>^fi^>V5 "' \\ * -i 

 .., - ) ^ft'fe 



y r\ A f x-^- * i 



* t^V 



P 



e 



^9Sw^ 



- Epithelium. 



Tunica propria. 



Portion of a capillary 

 blood vessel. 



Cuticula. 



Nucleus of a lympho- 

 cyte. 



Tangential section of a 

 goblet cell. 



Mucus in a goblet cell. 



Nucleus of a smooth muscle fiber. Central lymphatic vessel. 



FIG. 235. LONGITUDINAL SECTION THROUGH THE APEX OP THE VILLUS OF A DOG. X 360. 

 The goblet cells contain less mucus as they approach the summit of the villus. 



known that fat enters the lymphatic vessels so that they become distended 

 and white, their fatty contents being designated chyle. 



In regard to the absorption 

 of proteid material, the observa- 

 tions of Pio Mingazzini, which 

 have been confirmed by some 

 and denied by others, are of con- 

 siderable interest. As shown in 

 Fig. 236, he found that the basal 

 protoplasm of the epithelium 

 presented an ordinary appear- 

 ance before digestion (A), but 

 that after absorption had pro- 

 gressed, hyaline spherules ap- 

 peared in it (B). As these became numerous they were detached from 

 the cells, forming a reticular mass between them and the tunica propria (C). 

 14 ' 



FIG. 236. STAGES OP INTESTINAL ABSORPTION" AS 

 SEEN IN EPITHELIAL CELLS OP VILLI FROM A 

 HEN. (After Mingazzini.) 



A and D, The states of repose preceding and following 

 the process, s., Sphecules. 



