IMMUNOLOGICAL BEHAVIOR lOl 



(1935), joukow-W^ereinikow and Lipatova (i9'^3-34), and 

 others. 



It becomes oljxious Ironi the h)reg()ing that the active ])rinci- 

 ples of the phenomenon thus far studied can be specifically neu- 

 tralized by immune sera. These princijjles are unquestionably 

 antigenic. In studies on the antigenicity of the principles the fact 

 that all sorts of antibodies, including the neutralizing antibodies, 

 may occur normally was taken into consideration. The observa- 

 tions consisted, therefore, of comparatixe titrati(Mis of bleedings 

 prior to immunization xvith the active principles with those ob- 

 tained at various stages of imminiization. It was then obser\'ed 

 that the process of imnuniization \vith appropriate materials and 

 dosage could raise the neutralizing titer of B. typliosus sera from 

 o to 200-'500 neutralizing units per 0.25 c.c. of serum or produce 

 a 20 to 30 fold increase in neutralizing potency of those sera which 

 showed a certain amotnit of normal neutralizing antibodies. In 

 B. coli and meningococcus sera in doses of 0.5 and 0.25 c.c. re- 

 spectively, the immunization brought about not infrequently a 

 15 to 30 fold increase in the neutralizing potency. 



EFFECT OF BACTERIAL VARIATION UPON THE SPECIFICITY OF 

 ACTIVE PRINCIPLES 



Further proof that the active principles responsible for the phe- 

 nomenon of local skin reactivity are antigenically specific is also 

 brought out clearly by studies on neutralization of reacting fac- 

 tors deri\ ed from \ariants of certain bacterial species. 



Description of strains and variants : 



The jB. typhosus strains used for the experiments were designated Ty Tl 

 stock, Ty 157 stock, Ty 159 stock, Ty 864 stock, Ty 870 stock, and Ty 240 

 stock. The B. coli strains also employed for some experiments were called 

 C40 and C stock. These strains were kept in the laboratory collection for 

 from one to four years prior to this work. 



The colony appearance of these strains on plain agar, with the exception 

 of Ty Tl stock and C^^ stock, was of the normal smooth type. The Ty T^ 

 strain already described on page _^6, was rough-smooth. The B. coli strain 

 C_jo stock, kindly sent to me by Dr. Andre Gratia eight years ago, was a 

 typical rough strain obtained by him from a bacteriophage lysed culture. 

 The colonies were cauUflower and coarsely granular. 



Broth cultures of the various strains, with the exception of Ty Tl stock 

 and C^o stock strains, gave uniform growth after twenty-four hours of in- 

 cubation at 37.5° c. The Ty Tl stock strain produced, in addition to the 

 uniform cloudiness, an insignificant amoinit of precipitate which on shaking 



