SOME POINTS IN THE ANATOMY OF THE DIGESTIVE SYSTEM. 51 



The position of the ileo-cfecal orifice can be indicated on the 

 surface, as a rule, by the point of intersection of the intertuber- 

 cular and Poupart (not mid-Poupart) lines. A point 1 to 1^ 

 inches lower would indicate the orifice of the appendix. 



Development of ccecuin and vemniforrrh appendix. — The caecum 

 first appears in the embryo at about the fifth week (His) as a 

 small outgrowth of the wall of the primitive gut (mid-gut), not 

 yet differentiated into small and large intestines. At this time 

 the outgrowth is of the same size throughout, and is practically 

 equal to the intestines in diameter. I have examined a number 

 of older embryos with the following results: — About the 

 eleventh week, whilst the two divisions of the gut are still of 

 the same diameter, it has increased very considerably in length 

 (this latter being equal to about five times the diameter of the 

 intestine, and thus being relatively as long as in the adult), 

 but even at this early date the basal portion for about 

 one-fifth of its length is quite as wide as the intestine, whilst 

 the remaining four-fifths of the outgrowth. — the future appendix 

 — is only about one-half or one-third the diameter of the gut. 

 From this it is seen that, even at the tenth or eleventh week of 

 foetal life, the distal portion of the outgrowth, which subse- 

 quently becomes the vermiform process, is beginning to lag 

 behind in its development. 



The basal portion continues to expand with the gut, the distal 

 part grows rapidly in length, but otherwise enlarges very slowly, 

 so that toward the end of fcetal life the caecum has attained a 

 conical shape, the wider end joining the ascending colon, the 

 narrow end tapering gradually and passing into the vermiform 

 process. This form, known as the infantile type of caecum, is 

 retained for some time after birth, or even may (in two or three 

 per cent, of cases) persist throughout life. As early as the sixth 

 or seventh month of fatal life, the wall of the terminal portion 

 of the small intestine adheres to the inner side of the caecum for 

 some distance below the ileo-cffical orifice; indeed, for the 

 greater part of its length. And this connection, which is 

 rendered more intimate by the passage of two folds of peri- 

 toneum, one on the front, the other on the back between the 

 two parts, profoundly modifies the subsequent growth of the 

 caecum and determines very largely its adult form. For, when 



