56 THE COLON. 



valvulae conniventes are formed by the villous coat only : they 

 also project into the cavity of the intestine, while the valvulae 

 are laid on its surface. They pass only from one longitudinal 

 band to another, and, in consequence of this, the cells are small, 

 and the position of each band is very evident when the intes- 

 tine is laid open. 



The communication of the ileum with the great intestine has 

 been already stated to be on the left side of it, about two inches 

 from its commencement. The aperture is so constructed, that 

 it is considered as a valve, and is called the valve of Bauhin, 

 or of Tulpius, after the anatomists who have described it.* The 

 appearance of the aperture is as follows : If the caecum, with a 

 small portion of the ileum and of the colon may be separated 

 from the other intestines, and kept in an inflated state until it 

 be so dry as to preserve its form when opened, and then if the 

 caecum and colon be laid open opposite to the aperture of the 

 ileum, a large transverse ridge, resembling some of the ridges 

 or folds just described, will be seen projecting into the cavity of 

 the intestine. In the internal edge of this fold is a long slit or 

 Fig. 137.f opening, which forms the communication 

 between the two intestines. It is obvious 

 that the form of this fold must be that of a 

 crescent ; and that its two surfaces with the 

 slit between them, must have the appear- 

 ance of two lips, which would readily permit 

 a fluid or substance of soft consistence to 

 pass from the ileum into the great intestines, 

 but must impede, if not prevent, its passage 

 back ; especially if the large intestines were 

 distended, as then the lips would be pressed against each other. 

 When the peritoneal coat is dissected from each of the intes- 



* Posthius in 1566 ; Vidus Vidius about 1569 ; Albert! in 1581 ; and Varolius, 

 who died 1575, each lay claims to the discovery of it. Bauhin's claims are in 

 1579. H. 



f A view of the Ileo-co3cal valve as it appears in the dried intestine, b, The 

 upper segment of the valve, or ilio-colic as it might be called, which is horizon- 

 tal, a, The lower or ileo-ccecal forms an inclined plane of about 45, and both 

 are parabolic, c, The closed end of the caecum, d, Ascending colon tied and 

 cut off near its middle. e t Ilium opening into the colon, through the valve. 

 /, Appendicula vermiformis. 



