22 THE STORY OF THE BACTERIA. 



pieces and turning it over in new combination 

 to other forms of life. 



It was formerly believed that such lowly 

 organisms as the bacteria could spring at once 

 into being wherever in nature the conditions 

 were favorable, but this notion of spontaneous 

 generation has long since been given up, be- 

 cause it was shown to have depended upon in- 

 sufficient and crude observation. We now be- 

 lieve that every living thing comes from some 

 pre-existing living thing, be it man, beast, 

 plant, or cell, and this principle holds true as 

 well among the bacteria as among more highly 

 organized beings. 



There is an enormous number of different 

 species of bacteria, each one of which appears 

 to preserve its individual characters under all 

 the varying conditions and vicissitudes to which 

 it is subject. They are to be found every- 

 where in nature. Where putrefaction and de- 

 cay are going on they are most abundant, but 

 where any form of life can exist they are pres- 

 ent, either dry and inactive, or where moisture 

 and food are present, growing and multiplying 

 in such degree as their surroundings will per- 



