ROLE OF INFLAMMATION 1 75 



precipitate deri\ed from protein antigen-antil)ocly mixtures uj)on 

 the skill of normal rabbits is in sharp and clear contrast to the 

 effect of the intravenous injection of such a mixtme upon a site 

 prepared by bacterial filtrate. The latter consists of an immediate 

 profuse hemorrhage ^vhich appears within forty-five minutes to 

 two hours following the provocative injection and is associated 

 w ith prompt necrosis and extensi\e thrombosis in the small blood 

 \essels. The entire pictine reaches it maximum development 

 Avithin foiu' horns. The acute inflammatory reaction is apparently 

 secondary to the changes in the local vascidar system. The 

 prepared skin site shoAvs a reaction of uniform severity and is 

 predominantly hemorrhagic in nature. On the contrary, while 

 the Artlius phenomenon is essentially an inflammatory reaction, 

 it is first quite mild and only eventually becomes so intensified 

 after a number of \veeks of sensitization, that hemorrhagic and 

 necrotic types of inflammation may be induced. 



ROUTE OF INJECTION OF RE.ACTING FACTORS AND INCUBATION PERIOD 

 NECESSARY FOR ELICITATION OF THE STATE OF REACTIVITY 



The basic experiments described in the introductory chapter 

 sho^ved clearly that the essential prerequisite for reproduction of 

 the phenomenon of local skin reactivity is that the reacting factors 

 be introduced into the blood stream following the preparatory in- 

 jection into the tissue after a suitable interval of time. In this man- 

 ner extremely se\ere reactions may be elicited with minute quanti- 

 ties of active principles. Thus, in some instances 0.0003 c.c. of 

 meningococcus "agar washings" filtrate were capable of eliciting 

 typical reactions in a single prepared skin site. If one considers 

 that this amount is diluted in at least 100 c.c. of rabbit's blood, 

 and that a part of it may be lost in the tissue before reaching the 

 prepared skin site, the amount actually capable of inducing the 

 lesion may be less than 0.000003 c.c. in these instances. On the 

 other hand, no typical reaction results from an intradermal or 

 subcutaneous reinjectioii into the prepared skin site made after 

 \arious intervals of time. These facts were amply corroborated 

 by Ecker and \\'^elch (1930), Burnet (1931), Gratia and Liiiz 



(1932c), Bock (1932), Plant (1934), Apitz (1933/-'). Stolvhwo 



(1935, 1936) , P. Bordet (1936/;) , and others. 



Apitz, who studied the effect of repeated subcutaneous and in- 

 tradermal injections of acti\e jDrinciples of B. coli cultures noted 

 that the first intracutaneous injection of the filtrate elicited only 



