4qS THE RABBIT chap. 



co'ciim {ccec) — a structure not met with in cither the dogfish 

 or the frog, and only reaching such a relatively large size 

 as in the rabbit in certain other herbivorous Mammals in 

 which the stomach has a simple form : in those which 

 possess a complicated stomach (77;., Ruminants) the crecum 

 is comparatively small. It is continuous with the proximaj 

 end of the colon, which contains an intra-colic valve and 

 into which the round sac at the distal end of the ileum 

 opens by a circular aperture provided with an iko-coUe 

 valve. From this point arises the thin-walled cfecum, which 

 lies coiled on itself amongst the folds of the rest of the 

 intestine : it is about an inch in diameter, and a spiral con- 

 striction is seen on the outside marking the attachment, on 

 the inside, of a spiral valve — like that of the dogfish's in- 

 testine but narrower — which makes about twenty-four turns 

 and ends at the base of a blind, finger-shaped process, the 

 vermiform appendix, which forms the apex of the Ciecum. 

 The whole canal is supported by a mesentery (p. 27) which 

 has a very complicated arrangement in correspondence with 

 the numerous folds of the intestine. 



II will lie noticed that the inte.stine is nuich move difi'eienliated as 

 regards its sidjdivisions than in the \'crtclirales previously examined, and 

 also that it is relatively much longer, being lifteen or sixteen times as 

 long as the hod)-. 



On cutting open the small intestine, its mucous membrane is seen to 

 be raised into minute, finger-shaped elevations or villi, and here and 

 there certain i)alches present a honeycombed appearance : these portions 

 are known as Peye)^ :s patthf^, and, like the tonsils, thymus, and spleen, 

 consist of ntasscs i^i lymphoid follicles composed of a connective-tissue 

 framework in which numerous leucocytes are imbedded. Other 

 so-called 'iymphatic glands" or adenoitis are present in the mesentery 

 and elsewhere. I'eyer's patches also occur in the proximal end of the 

 colon, close to the ileo-colic aperture ; and the round sac with which the 

 colon communicates, as well as the vermiform appendix, are lined with 



