ROLE OF INFLAMMATION 169 



Under experimental conditions some^vhat different from those 

 employed by the autliors just quoted, Gerber, in my laboratories, 

 attempted systematic studies in order to determine further 

 ^vhether any parallelism could be disco\'ered bet\\een the skin 

 reactivity induced by active principles of the phenomenon and 

 the inflammation resulting from the intradermal injection of 

 these principles. Comparisons were made by him when: 



Group 1 — Bacterial filtrates possessing a very high skin-prepara- 

 tory potency were used; Group 2 — Skin-preparation was performed 

 with a large dose of bacterial filtrate of high potency and forty- 

 eight liours elapsed before reacting factors Avere injected; Groujj 

 3 — Skin-preparation was performed with bacterial filtrate almost 

 completely neutralized by homologous antitoxic horse serinn and 

 with non-neutralize filtrate and tiie jDhenomenon elicited in both 

 instances; Ciroup 4 — Skin-preparation by l^acterial filtrates of lo\v 

 skin-preparatory potency ^vas employed. (Figs. 11-13.) 



In this work Gerber (1936^) found that tlie degree of inflam- 

 mation that may follow skin preparation depends to a great extent 

 on the amount of bacterial filtrate injected. Also, filtrates of various 

 microorganisms produce different degrees of inflammation. Like- 

 wise, filtrates of organisms which possess little skin-preparatory 

 potency, such as Streptococcus hei)iol\ticus, occasion moderate or 

 marked inflammation with skin-preparation. Nevertheless, there 

 is no parallelism bet\\'een the skin-preparatory potency of a filtrate 

 and the inflammation resulting from its intradermal injection. 

 This is clearly demonstrated in the results of the experiments in 

 which identical degrees of inflammation followed skin prepara- 

 tion Avith a filtrate almost completely neutralized by homologous 

 antitoxic horse serum and from skin preparation ^vith non-neu- 

 tralized filtrate. The former filtrate, hoAve\er, ^vas capal)le of only 

 partially preparing the skin so that after intravenous injection of 

 the reacting factors only a slight reaction was obtained. Similarly, 

 a filtrate may possess a high degree of skin-preparatory potency 

 and yet the inflammation seen after intradermal introduction may 

 be slight. In this instance, the elicitation of the phenomenon re- 



FiG. 11. A. section of skin photographed inider low magnification, sho\\ing fnllv 

 developed phenomenon three and one-half hours after intravenous injection of 

 reacting factcjrs. There are marked inflammation, hemorrhage and thrombosis of 

 \eins. li, higlier magnification of section shown in Figure 1 lA, demonstrating extreme 

 vascular engorgement and perivascular collars of leucocytes, with infiltration of walls 

 and extravasatcd erythrocytes between connective-tissue fibers. (Gerber, i936rt.) 



