CLASSIFICATION OF THE BACTERIA. 61 
phenomena of reproduction by fission or by 
spores, as the only character which can serve to 
establish our natural genera; but, unfortunately, 
this has only been ascertained for a small number 
of bacteria, the Bacillus anthracis, for example. 
The genera of bacteria cannot have the same 
significance as among animals and superior vege- 
tables ; they can only be established in accordance 
with the most prominent characters, reserving the 
feeble modifications of these generic forms as 
specific characters. | 
Are there distinct, well-defined, species among 
the Bacteria ? 
The microscopists have given the most diverse 
opinions upon this subject. Miller, Ehrenberg, 
Dujardin, Davaine, have admitted the specific dis- 
tinction of the numerous vibrioniens which they 
have described. Davaine, however, raises some 
doubts as to the absolute value of the species 
established in his time. “Those which are de- 
scribed to-day by the classifiers,’ he says, “ ought 
to be considered as the expression of types under 
which are hidden a certain number of distinct 
species.” 
Cohn dwells still more upon the impossibility, 
in which we are to-day, of distinguishing with 
certainty genera and species among the bacteria. 
However, he is convinced that the bacteria are di- 
vided into species as distinctly as the other plants 
and inferior organisms. It is only the imperfection 
of our means of observation which makes it impos- 
sible to recognize these differences. ‘This is above 
