ROLE OF INFLAMMATION 155 



Xylol: 



The substance was rubbed into the skin of the abdomen and ear until it 

 flushed. This treatment usually resulted in formation of scabs. 



Eserine salicylate: 



One per cent solution of eserine salicylate was employed. 



Cantharidin plaster: 



One scpiare inch of the plaster was applied for one-half hour and im- 

 mobilized by means of adhesive tape. This treatment resulted in consider- 

 able local irritation. 



Hypertonic NaCl solution: 



Ten per cent sohuion gave primary hemorrhagic lesions. Fi\c jjer cent 

 resulted in swellings, without primary gross hemorrhage. 



Silver nitrate: 



The substance was used in dilutions 1:10. 1:25, 1:50, 1:75, and 1:150. 

 Most of the rabbits showed primary necrosis without hemorrhage. 



Gerber (iggGa) made histologic comparison of the effect of silver nitrate 

 when injected intradermally alone, ancl with subseqtient provocative injec- 

 tion of active principles. A rabbit received 0.25 c.c. of 1:50 dilution of silver 

 nitrate solution intradermally. The skin site was removed 28 hours later. 

 Grossly, there was a slightly elevated, sharply circumscribed, pale gray central 

 area of necrosis, 0.5 cm. in diameter, surrounded by a pink wheal that faded 

 gradually into the surrounding skin. Microscopically, there was a massive 

 collection of leucocytes extending from the epithelium down through the 

 subcutaneous tissue. The cells showed marked degenerative changes, particu- 

 larly in the central portion of the mass, where small foci of necrosis were 

 present. At the edges, the infiltrated area was marked off by a zone of edema, 

 discrete leucocytic infiltration and capillary congestion. No hemorrhages were 

 present. The overlying epithelium was infiltrated by leucocytes and the cells 

 swollen; many were degenerated. 



A second rabbit received a similar intradermal injection, followed twenty- 

 four hours later by 25 reacting units of B. typhosus, intravenously. The skin 

 site was removed four hours after intravenous injection. Both grossly and 

 microscopically, the changes in this instance were identical with the above 

 when no intravenous injection was given. 



It is evident, therefore, from Gerber's experiments, that silver nitrate is 

 incapable of preparing the skin for the elicitation of the phenomenon of 

 local skin reactivity in the rabbit, since the inflammation produced by the 

 intradermal injection of the silver nitrate was in no way enhanced by the 

 subsequent intravenous injection of bacterial filtrate. 



Histamine : 



Skin sites were prepared with histamine in dilutions 1:1000, 1:10,000 and 

 1:100,000 and with mixtures of histamine diluted 1:1000 with 2 per cent 

 solution of calcium chloride. 



