APPENDICITIS. 379 



the retroperitoneal connective tissue may become invaded during 

 the course of the disease. When the appendix lies in the 

 peritoneal sulcus between the caecum and the flank, the inflam- 

 matory mass may be found in the right loin, and is favourably 

 placed to infect the right kidney pouch of the peritoneum and 

 extend into the right subdiaphragmatic region. 



In rare instances the caecum fails to complete its migration 

 from the umbilical region to the right iliac fossa. In such cases 

 the abscess resulting from appendicitis may lie in the region of 

 the umbilicus or neighbourhood of the right kidney. If the 

 descent of the caecum fails to stop at the proper point both 

 caecum and appendix may be found in the true pelvis. When 

 the caecum is loosely attached to the abdominal wall the appendix 

 may wander into the left iliac region. It has also been found in 

 the sacs of umbilical, inguinal, or femoral herniae. Inflamma- 

 tion of an appendix in any of these abnormal situations may 

 give rise to great difficulties in diagnosis. 



The vermiform appendix is essentially a lymphoid organ. It 

 abounds in lymphatic tissue and closely resembles the tonsil. 

 This, together with the fact that it is a blind tube, explains its 

 proclivity to inflammation and perforation. In common with 

 other lymphoid aggregations, a certain amount of atrophy occurs 

 after middle life. Appendicitis is most common before this 

 retrogression occurs. The narrow lumen of the tube is easily 

 obliterated as a consequence of inflammation, and retention cysts 

 may arise as a consequence. 



The lymphatics of the appendix, which arise in the lymph 

 sinuses surrounding the lymphoid nodules, after traversing 

 some insignificant glands in the meso-appendix, terminate 

 in a group of glands near the ileo-caecal junction, round the 

 terminal branch of the superior mesenteric artery. These 

 glands may form part of the inflammatory swelling in appen- 

 dicitis. Suppuration in them is quite the exception. A group 

 of retroperitoneal glands along the inner border of the ascending 

 colon is frequently enlarged as well, as also are some glands 

 which lie alongside the right iliac arteries. An anastomosis 



