50 



Scientific Proceedings (iio). 



Experiment has shown that the poisons are not extractives of 

 the bacterial bodies. 



They are weakened and sometimes destroyed by heating to 8o° 

 for 30 minutes. 



They seem to be relatively more potent for rabbits than for 

 guinea pigs. 



They cause a marked reduction of leucocytes and probably in 

 this sense have a definite agressin-like action. Small doses of 

 streptococci injected with such substances killed, in some instances, 

 in a shorter time than did many times the amount of washed 

 organisms of the same cultures. 



In four separate experiments it has seemed distinctly as though 

 the first isolation of certain streptococci from the human body 

 gave rise to more potent poisons than we were ever able to produce 

 with the same organisms in later generations. 



Time experiments seem to show that the poisonous substance 

 is more plentiful in the cultures at about the period of the highest 

 growth energy of the organisms. 



There is no indication that there is any relationship between 

 these substances and virulence. 



The substances were produced on simple hormone media with 

 almost the same potency with which they appeared on the richer 

 protein media such as chocolate broth. In general, however, the 

 potency was in favor of the richer media. 



Many of the more accurate determinations of biological 

 properties, such as certainty about the temperature of destruction, 

 deterioration at room temperature, and relative toxicity for various 

 animals, are difficult to determine with absolute certainty because 

 of the great fluctuation in potency of the substances obtained and 

 the probable differences in susceptibility of individual rabbits. 



In spite of fluctuations of potency, however, some degree of 

 toxic action was never absent and its importance in connection 

 with animal immunization necessitated further study. 



As to the formation of these substances in the body of the 

 animal, we can say, at the present time, only that the symptoms 

 produced after an incubation of from 1 to 1 Yi hours in a rabbit are 

 similar in general to those which appear in a rabbit at the time 

 when the streptococci begin to appear in the blood stream in 

 considerable numbers. 



