128 ANTISEPTICS 



a few disinfectants, Pseudomonas could withstand strong- 

 er doses. It could resist 8 times as mucli hydrogen per- 

 oxide, 6 times as much acrifiavine, 3 times as much qui- 

 nine and silver nitrate, and twice as much picric acid as 

 Bacterium coli. These differences are small compared 

 with those found between Gram-positive and Gram-neg- 

 ative bacteria. 



There is an extensive literature on the addition to cul- 

 ture media of antiseptics which are meant to do no harm 

 to a certain desired species, but to suppress most or all 

 other species. The use of dyes for this purpose is quite 

 general. In water bacteriology, a soap, sodium ricinol- 

 eate, is used, and a great number of other media have 

 been proposed to separate Bacterium coli from other re- 

 lated species. To give just one instance of the compre- 

 hensiveness of the literature on that subject, it may be 

 noted that volume 19 of Milclnvirtschaftliche Forscliun- 

 gen contains not less than seven papers on selective me- 

 dia for the isolation of either Streptococcus agalacticae 

 (mastitidis) or Brucella abortus. It is, of course, be- 

 yond the scope of this review to discuss all the applica- 

 tions of the selective action of antiseptics to the isolation 

 of certain species. 



III. DILUTED DISINFECTANTS AS ANTISEPTICS 



The mode of action of antiseptics can be studied best 

 by beginning with the effect of diluted disinfectants. 

 Their lethal effect at higher concentrations, that is, the 

 irreversible inactivation of the mechanism of cell divi- 

 sion, is fairly well understood, but, as was pointed out in 

 the introduction, the reversible inhibition or retardation 

 of multiplication very probably is an entirely different 

 chemical reaction. 



To analyze the mechanism of growth inhibition, as was 

 also explained above, it is not sufficient to know the min- 



