400 LOCAL TLSSUE REACTIVITY 



pltostis and B. coll. It was IoiiikI that l)acteiial xaiialion induces 

 profound changes in the anti^enieity ol reacting factors. Reacting 

 factois obtained from \arious normal strains of B. typhosus differ 

 in their neiitrali/,al)ility by anti-stock innniine sera. Passage of 

 strains tlnough mice may decrease the neutralizability of their 

 reacting factors. The reacting factors derived from rough strains 

 can be neutralized only l)y anti-rough innmme serum. Work 

 along similar lines xvas then attempted with reacting factors of 

 meningococcus. Lhifortunately, variation in the meningococcus is 

 diflicult to demonstrate. No changes in the morphology of me- 

 ningococcus colonies have thtis far been induced by the usual 

 means known to incite microscopic dissociation in other bacterial 

 species (passage throtigh mice, ui vitro cultivation in immune 

 sera, etc.) (Hadley, 1927) . Hoxvever, it has been foinid in my 

 experiments ^vith meniirgococcus that passages of strains throtigh 

 mice as well as //* vitro passages through homologous immune 

 sera, bring about a considerable loxvering in the neutralizability 

 of their reacting" factors (Shxvartzman, 1931c, 1932^). Since it is 

 possible that bacterial variation occtirs in the course of sponta- 

 neous infectious diseases it is suggestive that a polyvalent thera- 

 peutic serum should include antibodies against the variant anti- 

 gens as well. 



It is also worthy of mention that passage of strains through 

 media containing human blood produces a marked effect on the 

 neutralizability of filtrates. In some instances, there was obtained 

 over 60 per cent higher neutralization with filtrates derived from 

 stock strains of meningococcus than with filtrates of the same 

 strains carried for 9 generations through human blood agar 

 plates. Not all strains, however, underwent this reduction in neti- 

 tralizability to the same extent. 



Poxvell and Jamieson (1931) reported that tests on 5 commer- 

 cial sera shoxved either Aveak neutralizing antibodies or practically 

 none at all. None of these sera Avas as potent as the best indi- 

 vidual horse serum prejjared by them and, therefore, they as- 

 sumed that in commercial production strong, weak, and inter- 

 mediate sera are pooled in each manufactured lot. According to 

 these aiuhors, the commercial sera, at the time of the tests, shoxved 

 no marked differences in agglutination contents. 



These authors also attempted to utilize meningococcus active 

 principles in addition to the regular suspensions of the cocci, for 

 horse immunization. In such treatment 2 of the usual intravenous 



