THE INTESTINES 237 



movement of this part of the digestive tube. Its terminal 

 portion, however, beginning at a point where the intestine 

 turns sharply forward on its way to the caecum, is adherent 

 to the mesocolon. 



(d) The mesenteric lymph glands (lymphoglandulae mesen- 

 tericae) are aggregated a short distance from the dorsal 

 attachment of the mesentery, where they form a compact 

 mass covering the left side of the superior mesenteric 

 artery. 



(e) The wall of the sacculus rotundus shows externally a 

 pattern of fine hexagonal markings, like the surface of a 

 minute honeycomb, on account of the presence in it of a 

 large number of lymph follicles. Structures of similar 

 composition and similarly marked, forming oval areas 

 about 3 mm. in diameter and 5 mm. in length, or somewhat 

 larger, may be found along the wall of the small intestine 

 (aggregated lymph nodules of Payer). 



(/) The finger-like processes, or villi, of the mucous tunic of 

 the small intestine may be seen by making an incision of the 

 wall and examining its internal surface. A small portion 

 of the wall may be excised and examined under water. 



4. Trace the course of the large intestine, beginning at the sacculus 



rotundus, as follows: 



Its first portion, the blind intestine or caecum (intestinum 

 caecum), distinguished by its great size, is connected with the 

 large intestine proper only in the region of the sacculus rotundus. 

 Strictly speaking, the caecum begins at the opening from the small 

 intestine, but in the rabbit and many other mammals its peculiar 

 structure extends a short distance beyond this point along the other 

 part of the large intestine, the colon. The caecum is so greatly 

 enlongated in the rabbit that it has become coiled in a spiral 

 manner and may be considered to consist of three limbs (Fig. 54), 

 the third terminating in the narrow^ but thick-walled vermiform 

 process (processus vermiformis) or appendix. The latter lies in a 

 dorsal position, and is directed backward. 



The second portion, the colon, comprising the major portion of 

 the large intestine proper, leaves the caecum in the region of the 



