1896 THE MICROSCOPE. 99 



Every form of life, whether animal or vegetable, flour- 

 ishes best under certain conditions as to temperature and 

 food, or soil. To this law micro-organisms, of course, 

 conform, and the presence of certain substances in the 

 nourishing medium is essential to the growth of both 

 bacteria and bacilli. Thus, disease-producing microbes 

 do not thrive well if proteicls and some organic salts aie 

 absent ; or if the nourishing material is distinctly acid. 

 Nevertheless, there is reason for believing some putre- 

 factive germs — which must be near relatives to certain 

 pathogenic organisms — are capable of rapid growth in 

 acid medium. In addition, many pathogenic organisms 

 remain inactive unless they are exposed to a certain de- 

 gree of heat — about the temperature of the human body 

 appears to suit them best — but their growth is quite 

 rapid until from 86° to 100° Fahr. is reached. Heat 

 above 140° Fahr. arrests the growth of many adult mi- 

 cro-organisms, and it may destroy some of them, al- 

 though it probably has no influence upon the spores of 

 the bacilli. 



An " antiseptic " is a substance capable of creating a 

 condition unfavorable to the growth and activity of mi- 

 cro-organisms. 



A " germicide " is a substance which will destroy the 

 vital action and the reproductive power of micro-organ- 

 isms. If, after pathogenic micro-organisms have been 

 placed in a , nourishing medium to which carbolic acid has 

 been added, upon the medium being exposed to such con- 

 ditions of heat and moisture as are favorable to the vital 

 activity of the organisms, the growth is retarded, the 

 conclusion is often reached that the carbolic acid is a 

 germicide, and that the disease-creating power of the 

 microbes has departed for ever. This reasoning is 

 fallacious, because the vital action of the organisms may 

 simply be retarded, in a manner similar to that by which 

 the application of cold inhibits microbic growth. In 



