362 PHYSIOLOGY OF BACTERIA 



This table resembles that of Gegenbauer's for the 

 Micrococci. Its concentration exponent is n = 0.25, 

 between 1.0% and 5.0%, or n = 0.23 between 0.1% and 



5%. 



This picture of disinfection is completed by an experiment with 

 cyanide of mercury. The action of this salt upon coagulated albumin 

 and yeast is quite different. In yeast, no definite compound of 

 mercury with protein had been formed in ten days, and with serum 

 albumin, very little was found after fifteen days. The distribution 

 factor for the dissolved salt between protein and Hquid was smaller. 



The disinfection experiments agree with this behavior. Since no 

 insoluble protein compound is formed promptly, chemical removal 

 of the mercury salt has no effect upon the killing time. Death, except 

 for the very lowest concentrations, is practically independent of the 

 concentration of the poison. The "fundamental reaction" must be 

 of a different nature here than in the case of the bichloride. 



Gegenbauer (1922) studied further the mechanism of formaldehyde 

 disinfection. He found a true physical partition of formaldehyde 

 between water and oil, as in the cases of phenol and HgCl2 mentioned 

 before; with yeast, however, there was no physical solution at all 

 in the solid phase, but a well-defined chemical compound was formed. 

 The amount of formaldehyde bound by yeast was independent of 

 the concentration of aldehyde. However, for shorter times, less 

 than six hours, the amount of formaldehyde bound by the yeast 

 protoplasm was proportional to the formaldehyde concentration. 



This is shown in the disinfection experiments. Both with Micro- 

 cocci and with anthrax spores, the rate of disinfection was quite 

 nearly proportional to the formaldehyde concentration, which means 

 n = I. 



Washing with water or counteraction of the poison with ammonia 

 did not alter the death rate materially. This is to be expected, since 

 there is no dissolved formaldehyde in the protoplasm; however, the 

 chemical compound between formaldehyde and protoplasm is so 

 stable and irreversible that it is not changed back by water or 

 ammonia. 



In summary, it has been shown in this chapter that 

 some very interesting efforts have been made to obtain a 



