46 Colonel Sir Almroth E. Wright [March 9, 



when they are drenclied at the outset with undihited carbolic acid or 

 concentrated solutions of iodine. 



This is not the place for any lengthy discussion of the reasons 

 for this failure of antiseptics. But the gist of the matter can be put 

 quite shortly. The current belief in the therapeutic efficacy of 

 antiseptics rests on experiments which are quite fallacious. They 

 are fallacious in that in them the antiseptic was applied in watery 

 media — media which left that antiseptic unaffected. To have value 

 — that is, to have application to conditions obtaining in vivo — 

 the experiments should have been conducted in pus or serum 

 — media which quench antiseptic action. Again, in the experi- 

 ments of the past the antiseptics were intimately mixed with the 

 bacterial suspensions ; whereas, applied in the wound the antiseptic 

 comes only into external contact with the infected wall, and the 

 inflowing discharges. Employed thus we cannot expect it to diffuse 

 into and exert a bactericidal effect either in the infected wall or in 

 the discharges. 



By reason of these considerations having been disregarded, the 

 issue as to whether antiseptics applied in the wound with prophylactic 

 intent can be of any use must be investigated de novo. 



Experimental Investigation of the Efficacy of Antiseptics. 



Let me now try to indicate to you what sort of experiments should 

 be undertaken before nourishing in connexion with a particular anti- 

 septic, the expectation that it is going to be efficacious for sterilising 

 and afterwards suppressing microbic growth in wounds. I can illus- 

 trate my points best if you let me show you here four tubes. 



In Tube No. 1 I have a suspension of microbes in water. I now^ 

 add an equal volume of the antiseptic I wish to test, and shake up 

 thoroughly. These are, as you see, conditions which give every 

 possible advantage to the antiseptic. It is applied in a non-albumin- 

 ous medium, and is intimately mixed with the microbes. To find 

 out whether the microbes have been killed I draw off a sample and 

 dilute with very many times its volume of nutrient medium. I then 

 incul)ate to see whether I get any bacterial growth. 



In Tale 2 I make the conditions more favoural)le to the survival 

 of the microbes — infinitely more favourable than if I left behind an 

 antiseptic in a wound. I have here a mixture of staphylococci, 

 streptococci, and gas-gangrene bacilli sus})cnded in serum, and I now, 

 AS in Tube 1, add an equal bulk of the antiseptic and shake up, and 

 I then, following the technique of Professor Beattie, pour on a little 

 hot vaseline wbicli will afterwards congeal. This, forming an air- 

 tight seal, will allow the gangrene bacillus, if it survives, to grow out. 

 It will also announce the growth of this microbe, for it will confine 

 any gas A^Jiich may be evolved from the culture. 



