STUDY OF ANTISTREPTOCOCCUS SERUM. 117 



be given 0.5 of a cubic centimeter of culture subcutaneously the 

 next day without any effect. A control given 0.001 of a cubic 

 centimeter of culture dies. The rabbit that receives serum remains 

 perfectly well, although it has received at least 500 times the fatal 

 dose of streptococci. 



A smaller dose of serum (5 c.c.) protected a rabbit against 0.001 

 of a cubic centimeter of a virulent culture, while the control that 

 had received one-tenth of this amount (that is 0.0001) died. We 

 offer these figures, not as a systematic tabulation of the preventive 

 power of horse serum but as results that occurred regularly during 

 our experiments.* 



A suitable dose of preventive serum, as in the case just men- 

 tioned, protects rabbits against the inoculation of streptococci. 

 If too small doses in proportion to the number of organisms in- 

 jected are given, the animals may simply resist longer than the 

 controls or show an apparent cure lasting long after any original 

 manifestation of the disease, but eventually succeeded by a rapid 

 reinfection with the streptococcus. 



These conditions will be considered later. For the moment we 

 shall consider briefly the effect of the sera on bacteria in vitro. 



1. ACTION OF THE SERUM IN VITRO. 



Marmorek's preventive serum is from a horse immunized against 

 the streptococcus. The serum has no bactericidal power for the 

 streptococcus. Bacteria inoculated in it do not, to be sure, grow 

 very rapidly or abundantly, but they grow quite as well in the 

 immune serum as they do in normal horse serum. 



Preventive serum mixed with fresh normal rabbit serum has also 

 no inhibiting power on the growth of the organism. Streptococci 

 grow equally well in a mixture composed of 1.5 c.c. of normal rabbit 

 serum and 5 c.c. of preventive serum, or in a mixture in like pro- 



* Petruschky, in two recently published articles (Zeitschrif t fur Hygiene) , as a 

 result of his experiments concludes that Marmorek's serum does not in the least 

 protect rabbits against streptococcus infection. Treated rabbits showed no 

 appreciable difference over the controls according to this author. It is evident 

 that Petruschky has experimented with a serum that was spoiled in some manner. 

 The efficacy of Marmorek's serum may be shown by the most elementary experi- 

 mentation, and consequently the experiments and conclusions of Petruschky 

 need not concern us as they do not deal with antistreptococcus serum as obtained 

 at the Pasteur Institute. 



