576 ■ BAOTERIOLOOY. 



The foregoing sketch aifords but an imperfect idea of 

 tlie vast amount of labor that has been and continues to 

 be expended upon this many-sided, fascinating topic. 

 Of necessity, many important contributions have been 

 omitted, but those noted ^vill serve to illustrate the lines 

 along which the solution of the problem has been 

 approached. As a result of such investigations, our 

 knowledge upon infection and immunity may at present 

 be summarized as follows : 



1. That infection may be considered as a contest be- 

 tween bacteria and living tissues, conducted on the part 

 of the former by means of the poisonous products of 

 their growth, and resisted by the latter through the 

 agency of proteid bodies normally present in and gen- 

 erated by their integral cells. 



2. That when infection occurs it may be explained 

 either by the excess of vigor of the bacterial products 

 over the antidotal or protective proteids pi-oduced by 

 the tissues, or to some cause that has interfered with the 

 normal activity and production of these bodies. 



3. That in the serum of the normal circulating blood 

 of many animals there exists a substance that is cap- 

 develop, to an alien medium of different physical and chemical char- 

 acteristics, and not as a result of vital activities exhihited by any of 

 the ingredients of the serum. 



His opinion is based upon the investigations carried on in his labo- 

 ratory by Jetter in 1892 and by Walz in 1899 (see Arbeiten aus dem 

 Path.-Anat. Institut zu Tubingen, Bd. i. and iii.). 



Eevolutiouary though it may be, this doctrine, coming as it does 

 from so distinguished an authority, must be given due considei'a- 

 tion. As yet, it has not attracted very general attention ; nor will 

 it, in all probability, iiutil the evidence advanced by Baumgarten 

 has been subjected to <;areful experimental scrutiny by other com- 

 petent investigators. Until such is the case, the matter may he held 

 mijudice. 



