ii6 



LOCAL TISSUE REACTIVITY 



in*; Uic neutral i/in<; j)()tciuy ol the sciiiiii was einjiloycd, the 

 precipitates proved active. Inasmuch as the jM)teiicy of the pre- 

 cipitates appeared only with the increase in the amotint of B. 

 l\l)/io.sus reacting factors in the niixttne, it became suggestive 

 that these precipitates, in contrast to those derived from serum -|- 

 antiserum mixtures (to be descriljed in Chapter ix) , possessed no 

 indej^endent reacting potency. In partially neutralized mixtures 

 {i.e., looo, 1500, 2000, 3000, B. typhosus reacting factors each 

 mixed with 1 c.c. of serum) the non-neutralized active principles 

 were associated with the precipitates. Thus, the precipitates de- 

 rived from mixttnes of 1000, 1500, and 2000 reacting imits per 1 

 c.c. of serum, were jjotent, ^vhilst the supernatant fluid from mix- 

 ttnes less than 3000 iniits ^vith 1 c.c. of serum was inacti\e. It 

 may be considered as conchisive that the mere formation of pre- 



Table V 



REACTING POTENCY OF PRECIPITATES AND SUPERNATANT FLUIDS 

 FROM MIXTURES OF B. TYPHOSUS FILTRATES WITH IMMUNE SERA 



+ = three rabbits tested showing severe hemorrhagic necrosis, 

 o = no reactions obtained in a group of three rabbits. 



cipitates and possible adsorption of the active principles is not 

 sufficient for their inactivation. This is also supported by numer- 

 ous observations in which immune sera ^vhich formed precipitates 

 ^vith the filtrates containing the active principles failed to neu- 

 tralize them. Apparently, therefore, the addition of homologous 

 neutralizing antibodies to B. typJiusus active filtrates results in 



