TOXICOLOGY AND PHARMACOLOGY 399 



who show that upon the death of the bacteria a part of the phenol 

 is liberated. 



The biological method regards the rapidity of death (measured by 

 the number of surviving bacteria) in known concentrations of the 

 disinfectant and during a known time for action. In this case, the 

 changes in concentration by means of the adsorbing microorganism 

 are not considered, as in the chemical method, but only the damage 

 to the microorganism. The method assumes that "the rate at which 

 the solution of a substance acts as a disinfectant is proportional to the 

 amount adsorbed from this solution" (MORAWITZ *). This method 

 also is open to the objection that microorganisms are not a single 

 mass with uniform vitality but a mixture in various stages of growth 

 and with varying resistance; so that it is possible that the curves 

 obtained do not represent the course of an adsorption in various 

 concentrations, but express the resistance at various stages of 

 growth. 



These criticisms are offered to show the difficulties encountered 

 in an experimental test. 



We may count in this group, also, the experiments in which an 

 insight into the mechanism of disinfection may be obtained, by 

 varying the number of bacteria with known changes in the concen- 

 tration of the disinfectant acting for a constant time (EISENBERG, 

 OKOLSKA) . 



As a result of biological methods, PAUL, BIRSTEIN and REUSS * came 

 to the conclusion that the death of dried adherent staphylococci in 

 oxygen or in mixtures of oxygen and nitrogen is due to the adsorption 

 of oxygen by the cocci. 



P. MORAWITZ l (loc. cit.) found a good agreement between the 

 figures obtained by KRONIG and PAUL, upon killing anthrax spores 

 with sublimate and the formula for adsorption. 



Accordingly, we learn from the quantitative tests that the dis- 

 tribution of a disinfectant between microorganism and solution 

 may possess the formula of a chemical combination (formaldehyd) of 

 adsorption (chloroform, silver nitrate) and of distribution in solvents 

 in accordance with HENRY'S law (phenol). In the following pages 

 we shall see that transitions between these different kinds of distri- 

 bution occur. 



It would certainly be an error to regard distribution as the essential 

 factor in disinfection. As a result of adsorption the germ is sur- 

 rounded by a highly concentrated film of disinfectant whose action 



1 This calculation is referred to in the communication of H. FREUNDLICH which 

 is mentioned in the paper of H. BECHHOLD * on Disinfection and Colloid Chem- 

 istry, page 23. 



