100 THE MICROSCOPE. July 



order to sustain an assertion that the carbolic acid was 

 anything more than a very mild antiseptic (if it is that), 

 another experiment is necessary. The microbes must be 

 removed and placed in a fresh nourishing substance. If 

 they should then cease to grow, notwithstanding the 

 presence of favorable conditions of heat and dampness, 

 the conclusion would unquestionably be justified that 

 the carbolic acid had injured or destroyed their vital 

 activity. 



Before a substance is pronounced a "germicide," bac- 

 teriologists take still greater precautions. After the 

 germs have been exposed to tlie action of the hypotlieti- 

 cal germ-destroyer, they are introduced into the bodies 

 of suitable animals — such as are believed to be especially 

 susceptible to the disease under observation — and if, 

 after the- lapse of sufficient time, and repeated trials, the 

 disease fails to make its appearance, the substance may 

 be pronounced a germicide, as far as that particular mi- 

 cro-organism is concerned. In cases involving microbes 

 producing spores, the supposed antiseptic cannot be re- 

 garded as possessing any valuable germicidal properties 

 unless it destroys the activity, not only of the adult or- 

 ganisms, bat also of the spores. 



It has already been mentioned that an abundant sup- 

 ply of oxygen is injurious to the activity of disease- 

 producing micro-organisms ; and this fact alone is suffi- 

 cient reason for keeping our houses well supi)lied with 

 fresh air, both in winter and in summer. A waler- 

 closet ought to be an apartment by itself (not a bath- 

 room) of which the window cannot be fully closed, for if 

 it can be shut there is sure to be some ignorant person 

 who will shut it, thus enabling the noxious gases to 

 circulate through the house. 



The following facts seem worthy of attention. 



Sporeless micro-organisms are destroyed in one and 

 one-half hours at a temperature a little above 212° Fahr 



