322 THE ADRENAL, GENERAL MOTOR, AND VAGAL SYSTEMS. 



intestine/' and to assist, if considered from our standpoint, 

 in asepticizing the contents of the lower end of the small intestine 

 by permeating it with mobile phagocytes and alexocytes. If we now 

 connect this fact with the predilection of Peyer's patches for 

 bacterial invasion in typhoid fever, it would seem as if func- 

 tional impairment of these organs would render possible the 

 pullulation of pathogenic organisms in the ileum. This would 

 normally lead to infection of the patches, and of the system 

 at large through the apertures. 



Besides this first, and we may add, very important pro- 

 tective function, the follicular sinus, by serving as a secondary 

 passage for the chyle, appears to afford a supplemental pro- 

 tection to the organism of no mean power when we consider 

 that it serves not only as a channel for freshly-manufactured 

 leucocytes, but that the follicle simultaneously receives freshly- 

 oxidized blood directly from the great arterial trunks, through 

 the mesenteric arteries. This blood, which reaches the lym- 

 phoid tissue through the rich intrinsic capillary net-work to 

 which we have referred, doubtless furnishes it with the various 

 elements required for the metamorphoses retrogressive and 

 progressive : noted by Flemming and others, then forces its 

 way into the sinus, carrying with it not only the newly-created 

 cells, but also serum supplied with all the defensive agencies 

 which the blood affords. The accumulation of Peyer s patches 

 in the lower two-thirds of the ileum seems to directly point to 

 this as the most toxic part of the canal and clinicians well 

 know how frequently this region becomes the seat of intestinal 

 disease. 



It would thus appear as if in the duodenum, the jejunum, 

 and the upper part of the ileum, the gastric juice, the secretion 

 of the crypts of Lieberkiihn and that of the glands of Brunner, 

 in addition to the ultravillous process, would subserve the 

 protective process; and that beyond this, to the end of the 

 ileum, the follicles, either solitary or agminated in patches, 

 the villous process plus the folliculous process, including the 

 output of lymphocytes into the intestine, united to accom- 

 plish the same prophylactic purpose. 



Solitary follicles are also very numerous in the caecum; 

 while in the vermiform appendix agminated follicles they are 



