IMMUNITY TO LOCAL SKIN REACTIVITY 1 45 



The phenomenon of local skin reactivity may be produced ir- 

 regularly in guinea pigs, goats, and horses. It fails completely in 

 mice and rats. 



It is possible to elicit passive innniuiity to B. lyjjhosus active 

 principles. /// vivo serum protection against these j^rinciples fol- 

 lows the law of midtiple proportions. Passive immunity is best 

 obtained when the immiuie serimi is injected intravenously one- 

 half hotu' prior to the intravenous injection of the active prin- 

 ciples. It is possible to prevent the occmrence of the local skin 

 reaction by an intravenous injection of serimi following the in- 

 travenous injection of the active principles provided, however, 

 the serum dose is very large and the serum injection is made 

 immediately after the filtrate injection. The greater the amount 

 of antiserum injected intravenously, the more efficient is the /// 

 vivo neutralization in a ratio distinctly greater than the (juanti- 

 tative increase of serum. 



