STREPTOCOCCUS INFECTIONS 247 



If we come to investigate the reasons which may be responsible 

 for this want of action, different possibilities suggest themselves. 

 On the one hand it is conceivable that the identity of the different 

 strains is only apparent and that Marmoreck's serum was inactive 

 merely because it was monovalent, i. e., because it had been produced 

 with but a single strain. If this were so it would evidently be 

 necessary to prepare a polyvalent antiserum, i. e., to immunize 

 animals with as many different strains as possible, and to use the 

 resultant product. Or, one might imagine that in consequence of 

 animal passage, to increase the virulence of a different strain, the 

 organism could become so altered in its biological properties that its 

 virulence for the human being would be diminished or lost, and that 

 the corresponding antiserum, though active for the animals through 

 which the passage had been conducted, might still be inactive in 

 the human being. In such an event, animal passage would have to 

 be omitted, and a monovalent or polyvalent serum prepared by 

 immunizing directly with strains that had been obtained from human 

 beings (sc., with cultures made from human sources only). 



Both possibilities have indeed been considered and practically 

 tested. Denys and Van der Velde thus prepared a polyvalent 

 serum from a number of different strains, whose virulence had been 

 further increased by animal passage, but this serum also has fallen 

 into oblivion, which suggests that subsequent investigations did not 

 support the favorable reports which first followed its introduction. 

 Tavel, Krumbein, and Paltauf, on the other hand, prepared polyva- 

 lent sera from different human strains without animal passage, 

 and Menzer and Moser monovalent strains which had likewise not 

 been passed through animals; while Aronson attempted a combined 

 procedure making use of passed and unpassed organisms conjointly, 

 both in the form of monovalent and polyvalent preparations. At 

 the present time practically all these products are in use, and while 

 they are unquestionably efficacious in the animal experiment, the 

 clinical evidence is still rather against than in favor of their real 

 value. This suggests the possibility, of course, that clinicians may 

 not apply the sera as promptly in streptococcus infections as is 

 done in diphtheria, and as a matter of fact there is a good deal of 

 truth in this criticism. That this factor may actually be one of 

 moment is suggested by the fact that the best results have thus far 

 been obtained in scarlatina, where the diagnosis is reached at an 



