12 THE BACTERIA. 
new transformations, metamorphoses produced, ac- 
cording to some savants, favored, according to 
others, but, without contradiction, accompanied 
by the development of bacteria;’ and, without 
wishing to attribute to these organisms a finality 
which is repugnant to our monistic conception of 
the universe, it may be said that it is thanks to 
them that the continuation of life is possible on 
the surface of the globe. 
But, if these studies are full of interest, their 
field is so vast that we cannot flatter ourselves 
that we have passed over the whole of it with 
equal care. ‘The little time that has been ac- 
corded us for the composition of this thesis will 
be our excuse for the inevitable imperfections 
which will doubtless be found in our work. 
1 The bacteria: such is the subject which has been imposed upon us ; 
but it is certainly useless to give the reasons which have caused us to 
study not only the bacteria properly so called, taking the word in its 
most restricted sense, but all the organisms which are comprised under 
the names of bacteria, vibrios, schizomycétes, schizophytes, ete. 
