THE DEFENSES OF THE BODY 271 



killed by exposure to the serum of animal blood free of all 

 cellular elements. These results naturally caused defections 

 from the ranks of Metchnikoff' s followers, especially since 

 Nuttall's deductions were fully confirmed by many dis- 

 tinguished experimentors. In consequence, for a number of 

 years after Nuttall's work, the cell-free fluids of the body 

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

 invading bacteria were concerned. 



The natural sequel of Nuttall's demonstration was a 

 general curiosity as to the manner in which the destruction 

 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 referred. 



Buchner demonstrated that active serum was robbed of 

 its germicidal power by dilution with water and by dyaliza- 

 tion; 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 appropriate designation. Hankin 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 investigations of 

 Vaughan and of Kossel led them to regard nucleins as the 

 most important constituents of the blood in so far as germi- 

 cidal action is concerned. Fodor believed, as a result of his 

 experiments, that the antibacterial action of the blood could 

 be appreciably accentuated by the addition of alkalies. 

 While Baumgarten and certain of his pupils referred the 



