3°4 



BIOLOGY AND ITS MAKERS 



his energies to the study of pathogenic protozoa and of some 

 bacteria. He observed the successive stages of generation 

 of some micro-organisms of birds and other animals, and 

 in 1905, he clearly demonstrated the spirochaete of syphilis 

 {Treponema pallida) the existence of which had previously 

 been made known by Siegel. 



Fig. 94a. — Fritz Schaudinn, 1871-1906. 



His researches were thorough as well as brilliant, and it is 

 largely owing to his influence that the importance of proto- 

 zoology is recognized as a special division of biological study. 



Bacteria and Nitrates. — One further illustration of the 

 connection between bacteria and practical affairs may be 

 mentioned. It is well known that animals are dependent 

 upon plants, and that plants in the manufacture of protoplasm 

 make use of certain nitrites and nitrates which they obtain 



