THE STORY OF THE BACTERIA. 39 



cal compounds which result from their life 

 processes. We can apply to them various 

 chemical substances which are called germi- 

 cides, or disinfectants, and find out to which 

 of these and in what strength they most readily 

 succumb. 



In this way a large number of different 

 species of bacteria have been studied, and 

 these have been arranged in groups which 

 have some characters in common. So that 

 already, although the study of the bacteria by 

 the new methods is of very recent date, we 

 have the outline of analysis tables, something 

 like those made for the identification of the 

 higher plants in Gray's " Botany," for instance, 

 by the use of which the student can identify 

 certain of the better known forms which he 

 may come across in his studies. 



The nomenclature in bacteriology is still in 

 a rather chaotic condition, but a beginning has 

 been made. The term bacteria (singular, bac- 

 terium) applies to the whole class of organisms 

 of whatever shape. They are also sometimes 

 called " germs." Micrococcus is the generic 

 name of the most common forms of the spher- 



