28° MORPHOLOGY OF THE BACTERIA. 
they are formed of a myriad of little bodies iso- 
lated or grouped, globular or linear, gifted or not 
with motion, sometimes colored. These variations 
constitute so many characters which require to be 
studied with some detail. 
§ 1. BacrErta In GENERAL. 
Form. — The bacteria, as understood to-day by 
most botanists, when considered in their separate 
state, are of two principal forms, — globular bod- 
les, or monads, and bodies more or less filiform, or 
bacteria properly so called. 
The globular bacteria comprise organisms round- 
ed, ovoid, sometimes elongating themselves into a 
tube (Warming). The Monas crepusculum of 
Ehrenberg may be taken as a type. This form 
includes also the JZicrococcus of Hallier, the M/- 
crosporon of Klebs, the round forms of the Amy- 
lobacter of M. Trécul, and perhaps the Microzyma 
of M. Béchamp. We will see farther on that 
these are very probably phases of development of 
the spores of bacteria, properly so called. 
The bacteria, not globular, present a greater 
diversity of form; they may be straight, undu- 
lating, or twisted in a spiral. 
The rectilmear bacteria are in some exactly 
cylindrical throughout their whole extent; and in 
this case they form very short cylinders, as in the 
Bacterium, Cohn, or cylinders of which the length 
is several times as great as the thickness, as in 
the Bactéridies (Bacillus ulna Cohn); others are 
