CLASSIFICATION OF THE BACTERIA. 53 



uncertain : they may belong to the schizomycetes 

 or be of inorganic nature." 



Place of the bacteria among organized beings. 

 Distinction between animals and vegetables. — The 

 characters which serve to distinguish the inferior 

 animal organisms from the inferior vegetable or- 

 ganisms are of two orders, optical and chemical. 



A. The optical characters are drawn from the 

 general form, the movements, and the mode of 

 reproduction. 



The morphological characters have no value 

 except among the larger species of bacteria. If 

 we bring together a Spirillum and a Spirulina, 

 Kiitz., their affinities will be apparent to every 

 one. It is not the same for the large species of 

 Bacillus, of which the relations with the Oscilla- 

 toria are evident. The rod form seems very spe- 

 cial, but it does not necessarily imply the vege- 

 table nature of the organisms which possess it. 

 Finally, the spherical bacteria, — Monas and Mi- 

 crococcus, — resemble entirely by their form some 

 infusorial animals. 



Movement is not a more special character. It 

 is now well proved that it does not belong exclu- 

 sively to animals, and that it is met with in a cer- 

 tain number of the inferior vegetables. 



In fact, the anatomical characters are not al- 

 ways absolutely reliable ; but it is from these 

 alone that Cohn first, then Davaine, have recog- 

 nized the bacteria as vegetables. 



B. Chemical characters. Robin depends upon 



