Chapter IX 



REACTING POTENCY OF NON-BACTERIAL 

 SUBSTANCES 



aS ALREADY emphasized, the essential prerequisite of the 

 L\ ])lien()inenon of local skin reactivity to bacterial filtrates 

 JL X is that the second injection be given by ^vay of the blood 

 stream. Whilst large doses reinjected locally remain ineffective, 

 an amazingly small cpiantity of toxic filtrate may elicit severe 

 hemorrhagic necrosis in the prej^ared skin sites {i.e., doses of 

 less than 0.0003 c.c. per kilo of body weight of certain batches 

 of meningococcus filtrates) . 



Inasmuch as these observations stiggested that there may be 

 necessary for the elicitation of the phenomenon some interaction 

 between the active principles injected and the blood of the 

 animal, it Avas of interest to determine ^vhcther a disttnbance 

 in the colloidal state of the blood Avotild bring about formation 

 of reacting factors. It ^vas foinid, then, that combinations of ani- 

 mal protein antigens ^vith homologotis antisera ^vere capable of 

 eliciting reactions typical of the phenomenon in skin sites pre- 

 jjared l)y bacterial filtrates. This chapter deals \vith the investiga- 

 tions of this problem. 



REACTING POTENCY OF MIXTURES OF ANIMAL PROTEINS WITH 

 HOMOLOGOUS ANTISERA 



Basic experiments: 



Mixtures of the animal proteins ^vith precipitating antisera 

 ^vere made in proportions yielding abundant precipitates unless 

 stated to the contrary. The antisera employed ^vere prepared by 

 the use of Avell known methods of immunization. Only sera of 

 high precipitating titer ^vere employed: ^vhen sera ^vere stored 

 for any length of time, their titers ^vere ascertained prior to the 

 experiments. The mixtures ^vere incubated in the water bath at 

 37.5° c. for tAvo' hours and kept in the refrigerator overnight. 

 When it ^vas desired to test the precipitates and supernatant fluids 

 separately, the mixtures were centrituged at high speed until the 



2.^8 



