144 HOUSEHOLD BACTERIOLOGY 



the daily newspaper, for which the discovery overnight 

 of a new "serum" seems to furnish an item of per- 

 petual interest. 



The reasons for this failure are in part evident to 

 experts in this field, in part are still very obscure, and 

 are too technical to be entered upon here. But the 

 eager and toilsome search goes on with such inspira- 

 tion as is ever his who deals with these urgent prob- 

 lems of life and death, and at any moment the key to 

 the riddle may lie in our hands. 



It would be interesting, did the scope of this article 

 permit, to look at the means by which the body pro- 

 tects itself against infection, not by neutralization of 

 poisons, but by the actual destruction of the poison 

 producers the bacteria themselves. Suffice .it to say 

 that here also, in this bacteria-destroying phase of 

 immunity germicidal immunity, it is called the body 

 does not command new forces or mechanisms, but 

 makes use of those which are maintained for its daily 

 service, but which in the emergency it wields to new 

 ends and with exalted energy. 



OTHER METHODS OF PROTECTION. 



When it was found that it was not possible at once 

 to secure antitoxic sera for other infectious diseases 

 in the w^ay which had been so successful with diph- 

 theria, the attempt was made to obtain protection in 

 some other way. The leading idea in these researches 

 was to find a method of adapting man to pathogenic 

 germs without exposing him in the process to the 



