198 LOCAL ILSSUE REACTIVITY 



lollowiii^ ihc j)ic'j)arati()ii. In soiiic cxpei imciits proxocatixe in- 

 jc'clioiis ol small doses ot a liltrate <^i\cn one-liall, one and two 

 liours lollowing the preparatory injections xvith such a mixture, 

 elicited severe and diffuse reactions. It is notewortln that the in- 

 cubation period and the dination ol reactivity may be consider- 

 ably siiorter than that loUowinj^ the intradermal preparatory 

 injection of bacterial filtrates. In the latter, at least eight hours 

 of incubation period are recpiired and it may last as long as 

 ninety-six hoins. 



Although the possibility of inducing the state of reactivity by 

 way of the vascidar system through a local vascular preparation 

 in combination Avith the testicidar extract is oljvious, the exact 

 conditions of its reproduction shoidd be considered Avith a great 

 deal of reserve. Apparently, there exist individual lluctuations in 

 susceptibility of rabbits vvhich may serve as a source of error. 

 These fluctuations are illustrated by some unexpectedly negative 

 residts. 



Inasmuch as the state of reactivity induced by way of the vas- 

 cular system with the aid of testictdar extract is of short dination. 

 larger provocative doses are necessary when the interval of time 

 is longer. Thus, positive residts were obtained in animals when 

 as many as 50 reacting units were used for the provocative injec- 

 tion twenty-four hours after preparation. Rabbits yielding" nega- 

 tive results received only 5 reacting units for the provocative 

 injection after the same interval of time. 



It is difficult to interpret the observation that heat and testicu- 

 lar extract were the only agents which allowed the preparation 

 of the rabbit's ear by way of the vascular system whilst numerous 

 substances employed which are capable of profoundly influencing 

 the capillary permeability, failed to do so. According to Duran- 

 Reynals (1928), McClean (1930), and Favilli (1931), the 

 Reynals factors are capable of producing striking and immediate 

 increase in dermal permeability which lasts for twenty-four hours. 

 The well known rapid spreading of testicular extract in the in- 

 jected site is due to an extreme dilatation of the capillaries and 

 lymph spaces. It is obvious that when an intradermal injection 

 of a bacterial filtrate is made for the purpose of elicitation of the 

 state of reactivity of the phenomenon under discussion, a peri- 

 vascular depot of the injected material is formed which comes 

 into continuous contact with the cells and blood vessels of the 

 site injected. The fact that an incubation period of at least eight 



