INFECTION AND IMMUNITY. 561 



were regarded as the real defenses of the body in so far 

 as invading bacteria were concerned. 



The natural sequel to NuttalFs demonstration was a 

 general curiosity as to the manner in which the destruc- 

 tion of bacteria was accomplished by the cell free 

 serum ; the conditions that modify the phenomenon ; 

 and the nature of the ingredient of the serum to 

 which the germicidal activity might properly be re- 

 ferred. 



Buchner demonstrated that active serum was robbed 

 of its germicidal power by dilution with water and by 

 dyalization ; that it was not affected by dilution with 

 physiological salt solution ; that it was rendered inert 

 by an exposure of fifty minutes to 55 C., and that it 

 was not affected by alternate freezing and thawing. 

 He concluded that the element of the blood to which 

 the function of killing bacteria may be ascribed is a 

 living albumen and suggested " alexin " as the appro- 

 priate designation. Haukin and Martin believed the 

 active germicidal principle to be a globulin, a view that 

 was to some extent suggested by the investigations of 

 Ogata and of Tizzoni and Cattani ; while the investi- 

 gations of Yaughan and of Kossel led them to regard 

 nucleins as the most important constituents of the blood 

 in so far as germicidal action is concerned. Fodor 

 believed, as a result of his experiments, that the anti- 

 bacterial action of the blood could be appreciably ac- 

 centuated by the addition of alkalies. While Baum- 

 garten and certain of his pupils referred the death of the 

 bacteria to purely physical conditions ; believing that 

 their exposure to blood serum having an osmotic tension 

 different from the fluids in which they had been grow- 

 30 



