828 THE POPULAR SCIENCE MONTHLY. 



ON THE DESTRUCTION OF INFECTIOUS GERMS. 



By Dr. A. WERNICH. 



THE theory that contagious diseases as well as putrefaction and 

 fermentation are developed and propagated by the agency of 

 organisms allied to the bacteria has been widely accepted, and is sup- 

 ported by the results of recent investigations. It becomes, then, of 

 paramount importance to ascertain the most efficacious means of de- 

 stroying these organisms. 



With this object in view, these researches into the conditions under 

 which bacteria may be destroyed have taken three directions : 1. To 

 test an observation made by Ernst Baumann, that the putrefactive organ- 

 isms in the course of their action develop carbolic acid, a deadly poison 

 to them, and to inquire whether there are not other poisons to bacteria 

 developed in a similar manner ; 2. Investigations prosecuted during the 

 prevalence of the plague to ascertain whether a dry disinfection of 

 clothing and goods could be made effective wholly to destroy the in- 

 fectious organisms ; 3. Having transplanted active infectious organ- 

 isms from one substance to another to which they are suited, to arrest 

 them in the most rapid stage of their development, destroy them, or 

 cause them to perish. 



In order to make the experiments of real value, a sure means must 

 be found of knowing whether the organisms are alive or dead ; they 

 may seem dead when they are only passive. The only unfailing test 

 is afforded by the reproductive faculty : when reproduction ceases, and 

 can not be excited, the organisms may be considered dead. 



Particular investigators have doubted whether it is possible wholly 

 to destroy these lower organisms. Naegeli * says it can not be fully 

 done without the aid of heat, and even heat is not always equally 

 effective. They are generally more easily destroyed by heat when 

 moist than when dry, but even a boiling heat will not destroy some of 

 them when they are in fluids of a neutral reaction. The more acid 

 the reaction, the less is the degree of heat that is required. The 

 degree of heat required to destroy the germs of infectious diseases is 

 believed to be greater than it is practicable to apply by the dry process 

 to clothing and similar materials. The capacity of many of the organ- 

 isms to reproduce may, indeed, be destroyed by a more moderate tem- 

 perature, but a question remains concerning the germs or spores which 

 had been taken up into the materials and were carried away with them. 

 These are believed to have some kind of a coating which enables them 

 to resist what destroys the parent organisms. 



In order to test the value of the dry process as applied to infected 



* Die niederen Filze in ihren Beziehungen zu den Iufektionskrankheiten und der 

 Gesimdheitspflege, s. 201. 



