22 IMMUNITY IN HEALTH 



The pyloric division of the stomach presents a num- 

 ber of solitary lymphatic nodules which become more 

 numerous as the pyloric sphincter is approached and 

 which continue into the proximal part of the duo- 

 denum. A special patch it is said often exists near the 

 entrance to the common bile duct. 



The noduli lymphatici aggregati {Peyer^s patches) 

 et solitarii of the small intestine occur in the jejunum 

 but are more frequent in the ileum especially towards 

 its lower end. The lymphatic nodules when single are 

 termed solitary and are irregularly dispersed, but when 

 collected together they form oval patches (^ to Ij 

 inches long) with their long axes in the axis of the bowel 

 and invariably situated on the side of the intestine 

 remote from its mesentery. It is said that from twenty 

 to forty-five of these patches may be found (Quain, 

 1912). The last one is situated a short distance from 

 the ileocaecal valve. They are not always easy to see 

 with the unaided eye. When inflamed or active they 

 may be more obvious from the peritoneal than from 

 the mucous aspect. 



The vermiform process (vermiform appendix) is a 

 blind tube one to six inches in length. Grayer has 

 recorded one over twelve inches long (Lockwood, in 

 AUbutt's System of Medicine). Its walls are thick, 

 and as much as half the thickness may be due to the 

 lymphoid tissue beneath the mucous membrane. The 

 lumen is small and contains a little material which is 

 similar to the contents of the caecum. The appendix 

 opens into the left side of the caecum about one centi- 

 metre below the ileocaecal valve, but that it represents 

 the original apex of the caecum is shown by the con- 

 tinuance to it of the taeniae coli. A moment's considera- 

 tion will show that the lymphoid tissue in the appendix 

 is situated on the side of the large bowel remote from 



