340 BIOLOGY OF PNEUMOCOCCUS 



trolled observations of the kind and are sufficiently suggestive to 

 encourage further study of pneumococcal poisons and of their an- 

 tigenic properties. 



Another report of a similar nature was that coming from Jamie- 

 son and Powell (1931) 676 who obtained from pneumococci toxic 

 substances not unlike those which have been demonstrated by other 

 workers as being produced by various streptococci. The action of 

 the substances could be demonstrated by skin tests on human be- 

 ings and on certain breeds of rabbits. By the same method, the se- 

 rum of horses treated by subcutaneous injections of the toxic sub- 

 stances could be shown to possess neutralizing properties for the 

 alleged toxin. The neutralizing principle could be concentrated to 

 a moderate degree in the refinement of globulins by the usual 

 chemical procedures and, according to Jamieson and Powell, was 

 independent of the small amount of protective antibodies present 

 in the serum. 



HEMOTOXINS 



In 1927, Neill, Fleming, and Gaspari 958 described the results of 

 studies on the antigenic or immunizing action of various prepara- 

 tions of pneumococcal hemotoxin. The power of the reduced and of 

 the reversibly oxidized forms of hemotoxin to evoke immunity were 

 identical, but preparations in which the hemolytic principle had 

 been rendered irreversible or destroyed by heat or by high con- 

 centrations of hydrogen peroxide were inactive in this respect. The 

 serum of rabbits and of horses injected with active hemotoxin neu- 

 tralized the substance, while the antigenic action of the hemotoxin 

 appeared to be independent of the protein fraction of the cell. 



Methods of Administering Antigens 



The manner in which Pneumococcus or its several antigens are 

 introduced into the body of an animal of any given species, other 

 factors being constant, may determine both qualitatively and quan- 

 titatively the nature of the immunological response. In the early 



