196 PROFESSOR CHRISTOPHER ADDISON. 



the large intestine quite intelligible, and seem to give to the fore- 

 going classification a rational basis. 



The longer or free border of the meso-appendix, though 

 terminating in greater part about half-way along the appendix, 

 can be traced as a rule as a small sickle-shaped band almost to 

 its extremity. 



(4.) Betro-colic Fold and Fossm (fig. 11, cases 19 and 33). — 

 The term retro-colic, as Berry (18) points out, as applied 

 to these fossie is best, because when present they extend more 

 or less upwards behind the ascending colon. He divides them 

 into internal and external. From my cases, however, only one 

 appears to be of any consequence — namely, the internal. 



A fold of peritoneum passing to the back of the csecum and 

 ascending colon frequently divides the region behind the 

 ceecum, external to the mesentery and the meso-appendix, 

 into internal and external parts. The external may be con- 

 verted into a wide pouch by the outer reflection of the 

 peritoneum on to the back of the ascending colon from the 

 body wall bending downwards and forming the upper limit 

 of a more or less wide pocket with its apex upwards. This 

 pocket, spoken of as the external fossa, can hardly be regarded 

 as possessing much significance. The appendix does not 

 pass into it. In one case — No. 39 — it was narrow, and might 

 have been of clinical importance. In the other cases where 

 it existed — Nos. 2, 4, 13, and 15 — it was so wide and shallow 

 as, with the possible exception of case 2, to be scarcely 

 worth the name of a pouch. 



Intermd Fossa. — The internal or proper retro-colic pouch is 

 of considerable importance. It existed in cases 3, 4, 11, 16, 19, 

 27, 33, and 39, or 20 per cent, of the cases. It often contains 

 the root of the appendix, the extremity or the whole of which 

 may be turned upwards into the pouch. Cases 33 and 19 

 presented good examples of this condition (fig. 11). 



The appendix was curved back into a less sharply defined 

 pouch in case 3. A glance at figure 11 shows quite well how, 

 in one of these cases, further absorption of the peritoneum by 

 the colon would produce an appendix wholly behind the 

 peritoneum, as in cases 14 and 15, in which the appendix 

 was firmly fixed in the connective tissue behind the large in- 



