REACTIVITY TO VARIOUS MICROORGANISMS 47 



of the cultures. Streptococci grown in various fluid cul tines, as 

 described previously, ^vere killed by toluene or removed by cen- 

 trifugation or removed by filtration through Berkefeld "V" can- 

 dles. The Berkefeld filtrates of cidtines elicited severe reactions 

 in 22 out of 44 rabbits tested (50 per cent) . Toluene-sterilized 

 cidtures, as well as the supernatant fluid of centrifugated cultures, 

 gave reactions in 26 of 53 rabbits tested (also about 50 per cent) . 

 As may be seen from these results, the presence of live organisms 

 in the material injected intravenously is not necessary for the 

 production of the phenomenon of local skin reactivity to Strep- 

 tococcus Jieniolyticus scarlatiuae. It may be also seen that the 

 streptococcal reacting factors are filtrable bacterial products. As 

 live cultines sho^\ed reactions in 66 per cent of the rabbits, it 

 ^voldd appear that some loss in the potency of these factors occins 

 when the streptococci are killed or removed. 



Attempts ^vere also made to increase the yield of toxic sub- 

 stances in the filtrates by previously adjusting the hydrogen-ion 

 concentrations of the cultme to various levels before filtration. 

 These procediues had no apparent effect on the potency of the 

 filtrates. 



A series of experiments in \\'hich the skin of rabbits w^as pre- 

 pared by the injection of filtrates of cultures of the streptococcus 

 and of toluene-killed cidtures and in which the same material was 

 injected intravenously, gave entirely negative results (Shwartz- 

 man. 1931^) • 



Reactions v^ith miscellaneous strains of Streptococcus hemo- 

 lyticus: 



Strains of Streptococcus hemolyticus pyogenes isolated from 

 various conditions, i.e., sinus thrombosis, mastoiditis and skin in- 

 fections, ^vere grown in either 0.2 per cent glucose l^roth for pe- 

 riods of t^vo to six days or brain medium of Toomey and Mc- 

 Clelland (1933) for periods ranging from nine to twenty days. 

 The skin of rabbits ^vas prepared by potent heterologous filtrates 

 and the various streptococcus preparations tested for reacting po- 

 tency. Glucose broth culture filtrates yielded potent reacting fac- 

 tors on a number of occasions. In some instances, brain medium 

 culture filtrates gave factors of high potency. Titrations to the end- 

 point sho^ved, ho^ve\er, only slight differences in the potency of 

 these two types of preparations. One of the strains of Streptococcus 

 hemolyticus, isolated from a case of mastoiditis, was especially 



