370 PATHOGENie MICROORGANISMS 



titles of 0.1 c.c. to each one or two cubic centimeters of a pneumococcus 

 broth culture caused lysis of the bacteria, rendering the culture fluid 

 transparent and clear. This phenomenon does not occur with strep- 

 tococci, and has been used to differentiate the two species. According 

 to the recent studies of Libman and Rosenthal,^ great reliance may be 

 placed upon this method. 



The most convenient reagent for use in the Neufeld bile test is a 

 10 per cent solution of sodium taurocholate in physiological salt solution. 

 This should be sterilized or kept on ice. One-tenth volimie of such a 

 solution produces prompt lysis in a broth culture of pnexmiococci. 



Decisive differential importance may be attached to the agglutina- 

 tions of these microorganisms in immune sera (see p. 364). 



The permanency of the various types in the pneumococcus-strepto- 

 coccus group is still open to question. E. C. Rosenow ^ has recently re- 

 ported that he has transmuted typical pneimiococci into typical hemo- 

 lytic streptococci by methods which he has not as yet fully described, but 

 among which were animal passage, growth in sjmibiosis with bacillus 

 subtilis, and growth in an atmosphere of oxygen. The pneumococci 

 when first altered took on the characteristics of the streptococcus 

 viridans, later of the so-called streptococcus rheumaticus, and finally 

 of streptococcus hemolyticus. Together with cultural characteristics 

 the pathogenicity of these various strains for rabbits changed. The 

 pneumococcus produced acute sepsis, the streptococcus viridans caused 

 endocarditis, the streptococcus rheumaticus periarticular or serous 

 arthritis, and hemolyticus suppurative arthritis. An intermediate stage 

 was found in which the organisms quite regularly produced myositis. 

 Although he was able to transmute these types one into the other in 

 both directions, Rosenow believes that the cultural characteristics 

 of each type correspond to a fairly definite type of pathogenicity both 

 in animals and man. This work has not as yet appeared in detail and 

 has not been confirmed. 



1 lAbman and Rosenthal, Proc. N. Y. Path. Soc, March, 1908. 



2 Rosmow, J. A. M. A., 1913, Ixi, 2007. 



