STUDY OF ANTISTREPTOCOCCUS SERUM. 113 



present; the same culture, when 24 hours old, entirely escapes such 

 phagocytosis. Even with the old culture, however, new organ- 

 isms are formed in the exudate after a certain time and kill the 

 animal. 



The fluid in which cultures have been grown for several days 

 apparently does not contain any perceptible amount of the substance 

 that prevents phagocytosis. Streptococci injected into the peritoneal 

 cavity of a guinea-pig prepared by bouillon are rapidly and more 

 or less completely taken up, depending on the dose employed. This 

 engulfing occurs to just as marked a degree if 3 c.c. of a filtrate from 

 a 24-hour culture is injected with the bacteria. The negative 

 chemiotactic influence, then, is a property which belongs exclusively 

 to living streptococci. We should like to insist on a correlation 

 between a negative chemiotactic influence coming from the bac- 

 teria and the presence of an areola about them ; this areola may 

 develop, not only about bacteria in the peritoneal cavity, but also 

 under the skin, in the blood and in the aqueous humor. 



The resistant qualities of streptococci. The property of repel- 

 ling leucocytes, which is of such value to the streptococcus, is 

 not the only property which this organism utilizes in growing in 

 animal tissues. We have already seen that a fatal relapse may 

 occur in guinea-pigs even several days after an apparent cure. 



The momentary arresting of the infection and the apparent 

 cure are due to the intervention of complete phagocytosis and the 

 consequent disappearance of free bacteria. These cases, which 

 in guinea-pigs are very rare, indicate that certain streptococci may 

 be very resistant and may remain alive within phagocytes, regain 

 their activity, and after several days give rise to a new culture 

 that kills the animal. 



This delayed outgrowth of streptococci, after an apparent -cure 

 of the animal lasting some days, happens in rabbits that have been 

 partially immunized by the injection of a certain amount of pre- 

 ventive serum. The following experiment shows that the strepto- 

 cocci in such a . rabbit may remain latent for a long time in the 

 phagocytes and after a long interval grow again. 



A rabbit was given 6 c.c. of pepton bouillon into the peritoneal 

 cavity and 3 c.c. of antistreptococcus serum subcutaneously. On 

 the following day 6 c.c. of a 3-day-old culture of streptococcus was 



