66 BAGTEBIOLOOY. 



to be destroyed are of such a character that they com- 

 bine with the disinfecting agent to form insoluble pre- 

 cipitates; these so interfere with the penetration of the 

 disinfectant that many bacteria may escape its destruc- 

 tive action entirely and no disinfection be accomplished, 

 though an agent might have been employed that would, 

 under other circumstances, have given entirely satisfac- 

 tory results. 



In the destruction of bacteria by means of chemical 

 substances there occurs, most probably, a definite chem- 

 ical reaction — that is to say, the characteristics of both 

 the bacteria and the agent employed in their destruction 

 are lost in the production of an inert third body, the 

 result of their combination. It is impossible to say 

 with absolute certainty, as yet, that this is the case; but 

 the evidence that is rapidly accruing from the more 

 recent .studies upon disinfectants and their mode of 

 action points strongly to the accuracy of this belief. 

 This reaction, in which the typical structures of both 

 bodies concerned are lost, takes place between the agent 

 employed for disinfection and the protoplasm of the 

 bacteria. For example, in the reaction that is seen to 

 take place between the salts of mercury and albumi- 

 nous bodies there results a third compound, which has 

 the characteristics neither of mercury nor of albumin, 

 but partakes of the peculiarities of both ; it is a com- 

 bination of albumin and mercury known by the indefi- 

 nite term "albuminate of mercury." Some such 

 reaction as this occurs when the soluble salts of mer- 

 cury are brought in contact with bacteria. This view 

 has recently been strengthened by the experiments of 

 Geppert, in which the reaction was caused to take place 

 between the spores of the anthrax bacillus and a solu- 



