IL. 
CLASSIFICATION. 
Tue earlier naturalists—Ehrenberg (1838), Dujardin (1841)— 
placed the bacteria among the infusoria; but they are now recog- 
nized as vegetable microérganisms, differing essentially from the 
infusoria, which are unicellular animal organisms. One of the prin- 
cipal points in differentiating animal from vegetable organisms 
among the lowest orders of living things is the fact that animal 
organisms receive food particles into the interior of the body, assimi- 
lating the nutritious portion and subsequently extruding the non- 
nutritious residue ; vegetable organisms, on the other hand, are 
nourished through the cell wall which encloses their protoplasm, by 
organic or inorganic substances held in solution. 
Ehrenberg (1838), under the name of vibrioniens, established four gen- 
era, as follows: 
1. Bactertum—filaments linear and inflexible. 
2. Vibrio—filaments linear, snake-like, flexible. 
3. Spirillum—filaments spiral, inflexible. 
4, Sptrochete—filaments spiral, flexible. 
Dujardin (1841) united the two genera Spirillum and Spirochete of 
reer and added to the description of the generic characters as fol- 
ows: 
1. Bacterium—filaments rigid, with a vacillating movement. 
2. Vibrio—filaments flexible, with an undulatory movement. 
3. Spirillum—filaments spiral, movement rotatory. 
It will be seen that this classification leaves no place for the motionless 
bacilli, such as the anthrax bacillus and many others, and does not include 
the spherical bacteria, now called micrococci. 
The classification of Davaine (1808) provides for the motionless, fila- 
mentous bacteria, but does not include the micrococci. This author first 
insisted that the vibrioniens cf Ehrenberg are truly vegetable organisms, 
allied to the algae. He makes four genera, as follows: 
Filaments straight or bent, ( Moving spontane- | Rigid Bacterium. 
but not in a spiral, ously, Flexible Vibrio. 
Motiouless, . Bacteridium. 
Filaments spiral, . : ‘ 3 : : ; Sprrillun, 
Following Davaine, the French bacteriologists frequently speak of the 
motionless anthrax bacillus as la bactéridie. 
Hoffman in 1869 included in_his classification the spherical bacteria, 
and pointed out the fact that motility could not be taken as a generic char- 
acter, as it was not constant in the same species and depended to some ex- 
tent upon temperature conditions, etc. 
