304 BIOLOGY OF PNEUMOCOCCUS 



precipitin reaction with Type III antiserum. The activity of the 

 enzyme was destroyed by heating for ten minutes at 60° to 65°. 

 Neither normal beef nor rabbit serum had any inhibiting effect on 

 its activity. 



As a means for measuring the enzymatic strength, Dubos and 

 Avery determined the minimal amount of a given enzyme prepara- 

 tion which would decompose one cubic centimeter of a 0.001 per 

 cent solution of specific Type III capsular polysaccharide in 

 eighteen hours at 37.5°, the decomposition of the carbohydrate be- 

 ing demonstrated by the disappearance of precipitating action in 

 the presence of Type III antipneumococcic serum. As the authors 

 stated, "The specific decomposition of the capsular polysaccharide 

 of Type III Pneumococcus, by the organism as well as by the en- 

 zymes it produces, illustrates once more the specificity of the types 

 of Pneumococcus, and confirms the fact that the capsular poly- 

 saccharides, and not some impurities carried along with them, are 

 responsible for type-specificity." 



EFFECT OF THE ENZYME ON THE CELE CAPSULE 



Inasmuch as the capsular substance in its native state forms a 

 morphological structure which conditions the antigenic and sero- 

 logical reactions of the pneumococcal cell as a whole as well as its 

 power to invade and multiply in the animal body, it became of spe- 

 cial interest to ascertain what effect this specific enzyme would 

 have on the encapsulated cells growing in vitro and in vivo. To this 

 end, therefore, Avery and Dubos performed a series of experi- 

 ments the results of which revealed the fact that the enzyme by it- 

 self is neither bacteriostatic, bactericidal, nor bacteriolytic, and 

 that, without impairing the viability of the cocci or without inhib- 

 iting the ability of the cells to synthesize polysaccharide, the en- 

 zyme, by decomposing the specific carbohydrate, merely deprives 

 the bacteria of their capsules. It was evident that the action of the 

 enzyme did not destroy the function of elaborating the capsular 

 substance, since organisms decapsulated by enzyme again formed 



