24 L. A. JULIANELLE 



3 days with 3 mice for each strain. After the third mouse, in no case 

 was staphylococcus demonstrable by smear or culture from the peri- 

 toneum indicating complete overwhelming of the 4 strains. Cultures 

 of the heart blood, which were made to test the invasive powers of the 



4 strains, were negative each day. Here, if anything, the virulence of 

 the strains should have increased by the animal passage, but instead 

 the organisms decreased, the more resistant organisms lasting until the 

 third passage. This would indicate that hemolysis is quite independent 

 of virulence. 



Later, in attempting to isolate a virulent strain, 3 different strains 

 from pus were injected into rabbits. Two strains injected intravenously 

 in amounts of3ccofa 24-hour broth culture caused no apparent effect. 

 The third strain 'caused death in 0.5 c c amounts within 2 days, and 0.25 

 c c amounts within 1 week, presenting in this case typical staphylococcus 

 lesions. This strain was used in our serologic work and designated as 

 LI. The point of interest here, however, is that although the 3 strains 

 were distinctly hemolytic, only 1 proved to be sufficiently virulent to kill 

 a rabbit. The combined evidence of these 7 strains makes plausible the 

 conclusion that hemolytic strains are not necessarily virulent. 



The second method that nonhemolytic strains would prove to be 

 avirulent was not tried. Nonhemolytic strains were not isolated during 

 the course of the entire investigation. However, a glance at table 4 at 

 this point will show that strains of an undoubtedly saprophytic character 

 are hemolytic. In a general way, perhaps, the strains requiring the 

 greatest time for hemolysis are probably the least virulent of any ; but, 

 on the other hand, the strains giving most rapid hemolysis may be 

 saprophytic. 



LEUKOCIDIN ACTIVITY 



It was not the purpose in this experiment to make a study of the 

 leukocidin produced by staphylococci. The subject has been well worked 

 out. The purpose was rather to determine whether hemolytic activity 

 bears any relation to leukocidin activity. 



Van de Velde 50 first demonstrated leukocidin by filtration in 24-hour cul- 

 tures. Later he and Denys M showed that the leukocidin was not specific, but 

 was a metabolic product which destroyed other tissue cells as well as leu- 

 kocytes. Bail 82 obtained a maximum production of leukocidin in 11 days. 

 Neisser and Wechsberg 2 added considerably to the knowledge of staphylo- 

 coccus leukocidin. Making use of the reduction of methylene blue by leuko- 

 cytes, they found that leukocidin appears in filtrates after 4 days and reaches 



ro La Cellule, 1894, 10, p. 403. 



51 Ibid., 1895, 11, p. 395. 



82 Arch. f. Hyg., 1898, 32, p. 133. 



