DISINFECTION STUDIES 217 



Now it would of course be extravagant to say, since the course 

 of disinfection is found to follow the monomolecular law, that 

 therefore a single molecular species is concerned. We can only 

 say that whatever the mechanisms are and whatever the number 

 of consecutive reactions may be, they leave dominant the effect 

 of bacterial concentration. We may say in other words that 

 we are fortunate in having to deal with a phenomenon in which 

 the effect of concentration can be found, and that we can formu- 

 late the course of the disinfection process in terms of an equation 

 expressing the relation of concentration to the course of the 

 process. We are, aware, however, of some of the factors that 

 affect the course of the reaction. These in the case of chemical 

 reactions, are enumerated and discussed by Mellor (1909). One 

 of them, the effect of successive intermediate reactions, has been 

 apphed by Osterhout (1917) in an interesting manner to biologi- 

 cal phenomena, and by Winslow and Falk (1920) to controvert 

 the notion that disinfection is due to a distribution of variable 

 resistances. 



We have already indicated that even in the case of a simple 

 chemical reaction known to involve only one molecular species, 

 the mechanisms of disintegration are unknown, or at least the 

 subject of dispute. The monomolecular law in such cases shows 

 only the course of the reaction as it is related to the concentra- 

 tion of reacting bodies. 



The analogy in the two cases should be plain. In neither case 

 does the monomolecular law tell us anything about the mechan- 

 isms concerned. In both cases the monomolecular law fonnu- 

 lates the relation between concentration and the course of the 

 process. 



If then we say that the course of disinfection is determined by 

 the distribution of varying resistances we add nothing to the 

 formulation of the experimental facts. We could just as well 

 say that the course of a monomolecular chemical reaction is 

 determined by the frequency distribution of resistance among the 

 individual molecules. 



In the criticism by Loeb and Northrop, by Brooks and by Smith 

 use is made of the fact that at the beginning and end of the dis- 



