398 COLLOIDS IN BIOLOGY AND MEDICINE 



The question of adsorption may be solved in one of two ways 

 which I shall call respectively the chemical and the biological 

 methods. 



The chemical method regards the microorganisms as a lifeless sus^ 

 pension. Suspensions are shaken with various known dilutions of 

 the disinfectant, and after the suspension is removed the amount of 

 disinfectant remaining in the fluid is chemically determined. From 

 this we learn how much has been absorbed by the microorganism in 

 the various dilutions. It is the same method that is usually employed 

 in chemical adsorption experiments. It may be criticized because it 

 determines the amount of disinfectant absorbed by the microorganism 

 but not the result of the adsorptive action, the disinfection. From 

 a concentrated solution much more disinfectant is removed than is 

 necessary for killing or inhibition. 



R. O. HERZOG and BETZEL * employed the chemical method, with 

 yeast as the microorganism. They obtained an adsorption curve 

 for chloroform and silver nitrate and a chemical combination for 

 formaldehyd. The results are interesting inasmuch as chloroform 

 obviously acts by reason of its lipoid solubility; I question whether 

 the precipitation of albumin by silver nitrate is the only factor which 

 determines its disinfectant action. The result for formaldehyd is 

 especially surprising; its powerful inhibitive action on development 

 is well known, however its lethal action was discovered to be much 

 weaker. We shall await with great interest the further prosecu- 

 tion of HERZOG'S experiments which promise an explanation of some 

 of the questions proposed. The results with phenol are quite compli- 

 cated. According to REICHEL,* in an aqueous solution of phenol 

 there is a distribution in accordance with HENRY'S law, i.e., as if it 

 were distributed between two solvents. This was demonstrated by 

 REICHEL * in the distribution of phenol between water and oil, albu- 

 min, cholesterin and the bodies of bacteria. This explains why phenol 

 is active only in relatively high concentration. Increasing NaCl con- 

 tent shifts the relative distribution in the direction of the nonaqueous 

 phase. According to REICHEL the disinfectant action depends on 

 the fact that phenol causes a shrinking of the albumin phase; this is 

 strengthened by the NaCl. In this way, the views developed by 

 K. SPIRO and J. BRUNS * are revived in modified form. 



R. O. HERZOG and BETZEL obtained an adsorption curve on treat- 

 ing yeast with a phenol solution weaker than one per cent. These 

 contradictory results may probably be explained by the primary 

 absorption of the phenol at the surface of the bacterial cell which 

 then in some way absorbs it until the body of the bacterium is 

 filled. This I infer from the experiments of E. KUSTER and ROTHAUB 



