664 THE INTERNAL SECRETIONS AND IMMUNITY. 



formation of a Peyer patch, including the central "secondary 

 nodule" of Flemming, 41 could as well be applied to splenic 

 lymphoid structures. These probably also subserve a dual 

 process, such as" that observed by Macallum in the intestine, 

 judging from .the fact that the splenic lymphocytes often con- 

 tain iron-pigment. This suggests that in the spleen the leu- 

 cocytes formed pass out into the pulp-channels and chemotac- 

 tically take up the iron-pigment then carry it to the liver via 

 the portal vein, just as in the intestine they are also formed 

 in the follicle, pass out into the intestinal tract, take a similar 

 supply, re-enter through the villi, and also proceed to the liver 

 via the portal vein. Again, the power of the intestinal leuco- 

 cytes to chemotactically take up iron-pigment demonstrates 

 their capability of acting similarly with bacteria; the same may 

 be said of splenic leucocytes, thus justifying MetchnikofFs view 

 that phagocytosis is one of the spleen's weapons in defense of 

 the economy. 



All these features emphasize the identity of the spleno- 

 pancreatic ferment as a prophylactic agency, and we now feel 

 that we can, with confidence, submit the following conclu- 

 sions: 



1. The spleno-pancreatic system, through the agency of its 

 proteid-digesting ferment, trypsin, protects the system against dis- 

 eases caused by toxic albuminoid bodies. 



2. The main toxic albuminoid bodies to the effects of which 

 the system is exposed are: 



(a) Toxins and diastases secreted by bacteria. 



(b) Vegetable toxalbumins. ^ 



(c) Proteid toxalbumins. > Toxic foods. 



(d) Peptone toxalbumins. J 



(e) Vegetable poisons. 



(f) Venoms. 



8. Trypsin is the constituent of antitoxin which splits the 

 toxins of the diphtheria bacillus into inert bodies. 



4' Trypsin is the constituent of blood-plasma which splits all 

 toxic albuminoids into inert bodies and thereby protects the system 

 against diseases due to their effects. 



41 We purposely omit the term "germ-center," employed by Flemming, to 

 avoid the confusion that its use would obviously entail. 



