12 MORPHOLOGY OF THE BACTERIA. 
The spherobacteria include only the genus Jf- 
crococcus. 
g. Micrococcus, Cohn (Hallier emend. — Micro- 
spheria, Cohn, ante). 
Cells colorless, or scarcely colored, very small, 
globular or oval, forming by transverse division 
filaments of two or several articles, in form of 
chaplet, or united in numerous cellular families, 
or in gelatinous masses, all deprived of move- 
ment. 
The species are divided into three physio- 
logical groups : — 
a. M. Chromogenes. 
b. M. Zymogenes. 
ce. M. Pathogenes. 
Section (a): Micrococcus CHROMOGENES. 
The pigmentary bacteria grow in the state 
of Zooglea upon the surface of the substances 
which furnish them with nutriment. They are | 
always alkaline; all are avid of oxygen; their 
morphological characters are identical, and one 
can only distinguish them by their different 
coloring properties. 
According to Cohn, they are veritable spe- 
cies; for 1. Their pigments offer the greatest 
diversity as to chemical action and by spectro- 
scopic analysis, etc.; 2. Each species cultivated 
in the most diverse media produces always the 
same coloring matter. 
