DISTRIBUTION 23 



its original mesentery and therefore sttictly homologous 

 with the Peyer's patches (Fig. 4). 



The vermiform appendix is able either to fill itself 

 from, or empty itself into, the caecum. 



I'he noduli lymphatici solitarii oj the large intestine 

 are scattered throughout from the caecum to the rec- 

 tum. A large patch is said to occur at the junction of 

 the rectum and anal canal. 



Fig. 4. 



J3iagram of Lymphoid Tissue near the Ileo-Ca?cal Junction, iUus- 

 trating- the serial homology of the lymphoid tisue in the vermiform 

 piocess (appendix) ^vith that of the noduli lymphatici aggregati 

 (Peyer's patches). 



The most significant fact in connection with the dis- 

 tribution of these subepithelial lymphatic glands is that 

 they are found wherever bacterial activities are great- 

 est. There are certain frontiers of the body which are 

 weak spots from the point of view of bacterial invasion. 

 The dry skin with its dense layers is usually a sufficient 



