428 PATHOGENIC MICROORGANISMS 



at room temperature caused decided reduction, but, kept in the 

 ice-box for this period, reduction was slight only. 



The substance is not apparently specific for any one variety of 

 cell, but as produced from most strains it may effect the red cells 

 of human beings, of mice and rabbits of sheep and of horses, indis- 

 criminately, though perhaps with quantitative differences. Both 

 Besredka and Braun failed to produce an anti-lysin for the strepto- 

 coccus substance. The nature of the anti-lytic properties possessed 

 by some normal sera is not entirely clear. Since it is an extremely 

 heat stable substance, being but incompletely destroyed at 100 C., 

 it has been suggested that it could not be an antibody in the ordinary 

 sense of the work, but may consist of lypoidal substances like choles- 

 trin in the blood stream. 



STREPTOLEUCOCIDIN. In 1905 Ruediger 89 observed that filtrates 

 of virulent streptococci would prevent the phagocytosis of non- 

 virulent streptococci by leucocytes. The same thing was affirmed 

 by Hektoen. 90 Recently, Nakayama 91 has made more detailed 

 studies of streptoleucocidin. He finds that, as a general rule, 

 hemolytic and non-hemolytic streptococci, when non-virulent, and 

 easily taken up by phagocytosis, under the influence of normal serum, 

 do not produce leucocidin. Virulent strains, however, which are not 

 phagocytable produce leucocidin in demonstrable quantities. In 

 cultures grown on 10 per cent serum broth, the largest quantity 

 of leucocidin was produced in from ten to twenty-four hours, after 

 which production fell off. The largest quantities were obtained in 

 broth containing goat serum and horse serum. There was a definite 

 relationship between the volume of production and virulence. The 

 substance was rendered inactive by heating at 58 to 60 for thirty 

 minutes. It was unstable on preservation, and could not be reac- 

 tivated by the addition of small quantities of fresh culture fluid. 

 Normal serum and leucocytic extract possess some anti-leucocydal 

 power, a property which is destroyed by heating at 70 for thirty 

 minutes. 



He mentions that immunization with streptococci did not produce 

 anti-leucocydal properties, but injections with the leucocydal culture 

 fluids were successful. The streptoleucocidin seemed to be distinct 



89 Euediger, Jour. A. M. A., 44, 1905, 198. 

 <JO Hektoen, Jour. A. M. A., 46, 1906, 1407. 

 91 Nakayama, Jour. Infec. Dis., 27, 1920, 86. 



