114 BACTERIOLOGY. 



sources of carbon were used, other nitrogen 

 salts might be employed. 



Bacteria, then, are able to construct their 

 body substance out of. various kinds of nu- 

 trient materials and also to produce the 

 organic pigments, or fermentation products 

 or poisons especially characteristic of individ- 

 ual species, and they are able to do this either 

 analytically or synthetically with almost equal 

 ease. This ambidextrous metabolic power 

 exists among bacteria to an extent known as 

 yet among no other living things, and these 

 organisms consequently occupy physiological- 

 ly even more than morphologically a kind of 

 intermediate place between animals and plants. 

 We know, of course, that every animal and 

 plant cell works analytically as well as syn- 

 thetically and that the earlier abrupt distinc- 

 tion between animals and plants, according to 

 which the former were supposed to be mechan- 

 isms adapted for oxidation, the latter mechan- 

 isms for reduction, does not exist. Neverthe- 

 less, the differences between the two groups 

 are considerable. 



Among bacteria themselves differences in 

 this respect may be remarked. While cer- 

 tain species appear able to work synthetically 

 just as easily as analytically, there are some 

 kinds which are better adapted to the one me- 



