REACTING POTENCY 2^ \ 



Rabbits were sensitized by single or repeated injections of 

 animal protein. After various intervals of time they were pre- 

 pared by single intradermal injections of 0.25 c.c. of midiluted 



V 





/ * 



Fk;. 28. Rabbit sensitized by single injection of horse sernm six days pie\ionsly, 

 received intradermal injection of 0.25 c.c. of undilutef/ B. typhosus active principles, 

 rwentv-four hours later rabbit was injected intravenously with horse scrum. Appear- 

 ance of reaction at prepared skin site one hour after intravenous injection of hor.se 

 serum. 



bacterial "agar ^vashings" filtrate. The skin-preparatory potency 

 of the filtrates employed ^vas ascertained in the tisnal manner 

 jMior to the experiments. TAventy-four horns after the skin jjrep- 

 aration, the rabbits received single intravenous injections of the 

 animal protein to which they were previously sensitized {i.e., 

 test injections) . For repeated skin preparations and retests Avitli 

 the same or various proteins, a different bacterial filtrate was 

 employed each time in order to avoid acquirement of specific 

 active immunity. They Avere B. typlwsus, meningococcus Group 

 III (44B. strain) , meningococcus Group I (44D. strain) . and 

 B. coli "agar washings" filtrates, respectively. 



