270 LOCAL ILSSUE REACTIVITY 



lo these authors that the cHffereiKes in reactivity could be altrib- 

 uted to the ai^e ol the animals, a higher iiuideiue ol reactions 

 l)ein<> obtained in rabbits \\ei<'hin<' 'iooo '>nrs. or more. In order to 



I'K;. 27. Rabbit sensiti/ect Ijy sint^le injection ol horse seiinn six days pie\ itmsly, 

 received intradernial injection of 0.25 c.c. of inidiiiited B. tyj^hosiis active principles. 

 Twenty-four hours later rabbit \\'as injected intravenously \\'ith horse serum. Appear- 

 ance of reaction at prepared skin site one-lialf hour ailer intra\enous injection of 

 horse serinn. 



exclude the possibility that hjrtuitoiis contamination Avith bacte- 

 rial products was the agent responsible for the reacting potency of 

 starch, the authors digested starch solution \vith saliva until the 

 starch gave no color reaction when tested ^vith iodine. Rabbits did 

 not react to digested starch. The authors, however, did not control 

 the effect of saliva upon bacterial reacting factors. 



IN VIVO FORMATION OF REACTING FACTORS IN RABBITS ACTIVELY 

 SENSITIZED TO PROTEINS 



The next step ^vhich suggested itself in the investigations was 

 to determine whether the reaction between the antigen and anti- 

 body induced i?i vivo woidd bring about formation of reacting 

 factors in the blood stream. 



