288 BACTERIOLOGY. 



menters differ materially on certain fundamental points. 

 Some regard the streptococci encountered in different 

 diseases as possessing specific relations to such diseases ; 

 as, for instance, the streptococcus found in cases of 

 scarlet fever is believed by Moser and others to be specific 

 for that disease, and consequently the antistreptococcus 

 serum obtained by immunization with such an organism 

 is believed to possess far less curative properties against 

 other streptococcus infections. If this idea should 

 prove correct then it will be necessary to obtain serum 

 from animals that have been simultaneously immun- 

 ized with a number of different streptococci derived 

 from various disease conditions a so-called polyvalent 

 serum. 



Other experimenters believe that the frequent passage 

 of a culture of streptococcus through the lower animals 

 renders it less virulent, or at least alters its virulence 

 for human beings, and that the serum obtained through 

 the immunization of animals with such cultures is less 

 efficacious than when the original virulence of the 

 organisms is maintained by cultivation on suitable 

 media. 



Though all experimental evidence contraindicates the 

 production of soluble toxins in large amounts by the 

 streptococcus when grown in artificial media, Marmorek 

 still believes that by special methods of cultivation the 

 toxin-forming powers can be augmented, and that the 

 immunization of animals with such cultures serves a use- 

 ful purpose in giving the serum of the treated animal a 

 more definite antitoxic power. 



Aronson prepares his antistreptococcus serum by 

 immunizing horses with streptococcus cultures that have 

 been rendered highly virulent by repeated passage 



