II. ANTISEPTICS 



Under this general term are assembled those com- 

 pounds which are used primarily to prevent multiplica- 

 tion of bacteria but are not intended to produce com- 

 plete sterility. While disinfectants, as was already said 

 above, disrupt the reproduction mechanism irreversibly 

 and irreparably, antiseptics prevent multiplication only 

 as long as they are present; their removal permits the 

 various cell mechanisms to resume their normal function. 

 It was also pointed out that antiseptics often kill some 

 or even many of the cells, but death then occurs at such 

 a low rate that it would take weeks or even months to 

 achieve complete sterility. In some cases, this slow death 

 occurs only at the start and is followed later by a period 

 of no further dying, and sometimes even by multiplica- 

 tion. 



The practical efficiency of antiseptics can be measured 

 only in one way, namely by determining the lowest con- 

 centration which prevents multiplication. The inhibit- 

 ing dose may vary not only with the medium and the 

 temperature, as would be expected from analogy with 

 disinfectants, but also with the number of cells present. 

 For example, the multiplication of Bacterium coll in 

 broth is completely inhibited by 1 :100,000 crystal violet 

 if only 100 cells per cc. are present; but with 10,000 

 cells per cc, multiplication sets in after a temporary 

 delay. That delay in multiplication does not occur with 

 disinfectants; with them, when larger inocula require a 

 longer exposure time\ it is to cause death, not to retard 

 multiplication. 



1. See p. 54. 



