THE WORLD OF MICROSCOPIC LIFE 57 



the enormous development of bacteriology is one 

 of the most striking features in the history of the 

 nineteenth century, a history especially noteworthy 



, -. •»iJ.~'V.-; v \.-'. 



• •-.,v-.>.-iV 



Fig. 6. A Test Tube Plugged With Cotton and Showing 

 a Bacterial Colony Growing in the Culture Medium 



for the advance of science. For over a century and 

 a half following their discovery by Leeuwenhoek, 

 the great importance of bacteria was practically 



