THE C^CUM. 1665 



This, to a greater or less extent, is the normal condition. There is no doubt that in 

 the great majority of cases the appendix is wholly behind the caecum, mesial to it, 

 or below it. Monks and Blake found a reference to this point in the records of 

 572 autopsies. It was "down and in" 179 times, "behind" with no statement of 

 the direction 104 times, "down" 79 times, and "in" 62 times. Thus in almost 

 three-quarters of the cases it was in one of these positions. It ran " up" 52 times, 

 "up and in" 39 times, and "up and out" 29 times. In 9 cases it was "out," 

 "down and out" in 5, and "in pelvis" in 14. It sometimes is attached to the as- 

 cending colon by its peritoneal fold, and runs upward with probably accidental incli- 

 nations to one side or the other. It may also be found in some of the peritoneal fossae 

 of the region. In many of the cases marked "down and in" it hung over the 

 pelvic brim. Of 123 cases in which the appendix was covered by peritoneum, and 

 therefore presumably normal, Ferguson 1 found it hanging downward in n, placed 

 mesially in 18, on the right of the caecum in 19, and behind it in 75. Total absence 

 of the appendix is extremely rare, but has been observed by ourselves and others. 



Obliteration of the Cavity of the Appendix. The adenoid tissue of the vermiform ap- 

 pendix is, as elsewhere, most developed in childhood and tends to atrophy in middle life. 

 Coincident with this atrophy is a tendency (the cause of which is not clear) in the walls to 

 adhere, more or less obliterating the cavity. Ribbert * found in 400 specimens more or 

 less obliteration in 25 per cent., and, putting aside those under twenty years, in 32 per cent. 

 After fifty it occurred in more than 50 per cent. He found, however, the obliteration complete 

 in only 3^ per cent. In approximately one-half of the cases it involved only about one-half 

 of the tube. The process usually begins at the closed end of the tube, and is much more fre- 

 quent in short than in long appendices. Zuckerkandl 3 observed more or less obliteration in 

 23.7 per cent, of 232 specimens, the process being nearly or quite complete in 13.8 per cent. 

 Ribbert saw the process beginning in childhood, but never under five years. Fawcett and 

 Blatchford* found the appendix pervious 196 times in 221 cases, and 91 of the pervious ones 

 were from those over fifty years. We agree with them that much more conclusive evidence is 

 needed to establish the existence of a special atrophy of the appendix in old age or after 

 middle life. 



Peritoneal Relations. The caecum, being originally an outgrowth from the 

 convex side of the primitive intestinal loop, is completely covered by peritoneum 

 and has no mesentery, since the mesentery of the ileum passes directly to the colon. 

 The appendix, being the original end of the caecal pouch, is consequently also com- 

 pletely invested with peritoneum. When the ascending colon has come to lie in the 

 right flank, the posterior layer of its mesentery degenerates into areolar tissue, fusing 

 with that resulting from the degeneration of the parietal peritoneum behind it, and 

 by the same process the back of the colon is attached by areolar tissue to the 

 abdominal wall behind. This condition almost always ends a short distance above 

 the caecum. It is far more common to find the lower third of the ascending colon 

 with peritoneum on its posterior surface than to find none on the upper posterior 

 part of the caecum. This condition, indeed, does occur, we having seen it at birth ; 

 but it is very exceptional. From the preceding facts it follows that the caecum 

 and the appendix can have no mesentery in the strict sense ; nevertheless, the 

 term mesentery of the appendix, or meso-appendix (mesenteriolum processus vermi- 

 formis), is applied to an almost constant fold of peritoneum, presumably caused 

 by the artery of the appendix, which usually is attached to nearly the entire length 

 of that organ. Authorities differ widely as to how far the line of attachment ex- 

 tends along the appendix. Beyond question it is very variable. According to 

 Monks and Blake, it extends nearly or quite to the end in fully one-half of the 

 cases, and in most of the other half it reaches or passes the middle of the appendix. 

 Its general appearance is triangular, but, according to both Jonnesco 5 and Berry, 6 

 with whom we agree, it is more properly described as quadrilateral. One side runs 



1 American Journal of the Medical Sciences, 1891. 



2 Virchow's Archiv, Bd. cxxxii., 1893. 



3 Anat. Hefte, Bd. iv., 1894. 



* Proceedings of the Anatomical Society of Great Britain and Ireland, Journal of Anat- 

 omy and Physiology, vol. xxxiv., 1900. 



5 Hernies internes rtro-peYitonlales, Paris, 1890. 



6 The Caecal Folds and Fossae and the Topographical Anatomy of the Vermiform Appendix, 

 Edinburgh, 1897. 



105 



