40 ON THE ANTISEPTIC PRINCIPLE 



only with the point we are immediately considering, but with the whole subject 

 of this paper. 



If a perfectly healthy granulating sore be well washed and covered with 

 a plate of clean metal, such as block-tin, fitting its surface pretty accurately, 

 and overlapping the surrounding skin an inch or so in every direction, and 

 retained in position by adhesive plaster and a bandage, it will be found, on 

 removing it after twenty-four or forty-eight hours, that little or nothing that 

 can be called pus is present, merely a little transparent fluid, while at the same 

 time there is an entire absence of the unpleasant odour invariably perceived 

 when water dressing is changed. Here the clean metallic surface presenting 

 no recesses, like those of porous lint, for the septic germs to develop in, the 

 fluid exuding from the surface of the granulations has flowed away undecom- 

 posed, and the result is absence of suppuration. This simple experiment illus- 

 trates the important fact, that granulations have no inherent tendency to form 

 pus, but do so only when subjected to a preternatural stimulus. Further, it 

 shows that the mere contact of a foreign body does not of itself stimulate granu- 

 lations to suppurate ; whereas the presence of decomposing organic matter 

 does. These truths are even more strikingly exemplified by the fact, which 

 I have elsewhere recorded,^ that a piece of dead bone, free from decomposition, 

 may not only fail to induce the granulations around it to suppurate, but may 

 actually be absorbed by them ; whereas a bit of dead bone soaked with putrid 

 pus infallibly induces suppuration in its vicinity. 



Another instructive experiment is to dress a granulating sore with some 

 of the putty above described, overlapping the sound skin extensively, when 

 we find in the course of twenty-four hours that pus has been produced by the 

 sore, although the application has been perfectly antiseptic ; and, indeed, the 

 larger the amount of carbolic acid in the paste the greater is the quantity of 

 pus formed, provided we avoid such a proportion as would act as a caustic. 

 The carbolic acid, though it prevents decomposition, induces suppuration — 

 obviously by acting as a chemical stimulus ; and we may safely infer that 

 putrescent organic materials (which we know to be chemically acrid) operate in 

 the same way. 



In so far, then, carbolic acid and decomposing substances are alike — namely, 

 that they induce suppuration by chemical stimulation, as distinguished from 

 what may be termed simple inflammatory suppuration, such as that in which 

 ordinary abscesses originate, where the pus appears to be formed in consequence 

 of an excited action of the nerves, independently of any other stimulus. There 

 is, however, this enormous difference between the effects of carbolic acid and 



* See p. 1 6 of tliis volume. 



