IMMUNITY 201 



ascribed powerful bactericidal properties to the nucleins, 

 and surmised that in serum the nucleins set free by the 

 disintegration of leucocytes and other cells are the germi- 

 cidal agents. Forrest and the writer 1 found, however, 

 that all the germicidal properties ascribed by Vaughan 

 to the nucleins are probably due to the weak alkali in 

 which the nucleins were dissolved, and came to the con- 

 clusion that Vaughan's results are at least not proven. 



Gengou also found that the plasma collected in vaselined 

 tubes is often almost devoid of bactericidal power, whilst 

 the corresponding serum may be capable of destroying 

 large numbers of micro-organisms. 



We therefore see that while the blood, lymph, and 

 other fluids and tissue juices undoubtedly exert more or 

 less germicidal action on bacteria experimentally in vitro, 

 there is often a marked difference in this respect between 

 the circulating blood and the blood in vitro and it may be 

 doubted if this factor is of great importance in the produc- 

 tion of natural immunity. At the same time, it is to be 

 noted that directly infection has started more or less cel- 

 lular disintegration and serous exudation occur, and thus 

 the germicidal action of the body fluids and tissues may 

 be exerted in vivo, though such substances may act rather 

 by stimulating the leucocytes or by rendering the bacteria 

 more phagocytosable, as will be referred to later (p. 209). 

 Thus Kanthack and Hardy found that the coarsely 

 granular oxyphile leucocytes in the frog are first attracted 

 to the site of a bacterial invasion, there discharge their 

 oxyphile granules, the bacteria then show signs of degenera- 

 tion, and polymorphonuclear leucocytes and other " phago- 

 cytic " cells now approach and ingest the degenerate 

 bacteria. The observations, however, do not seem to have 

 been confirmed. Wooldridge also protected animals from 

 anthrax by injections of " tissue fibrinogen " (nucleo- 



1 Journ. Roy. Army Hed. Corps. 



