922, THE BACTERIA. 
cex, with several families with which the different 
genera of bacteria have many affinities. He rec- 
ognized, however, that the absence of chlorophyll 
approaches them, at least from a functional point 
of view, to the fungi. Upon this point we may 
say that for other botanists this character is de- 
cisive, and the bacteria are classed as fungi. 
M. Nageli, who takes this view, describes them 
under the name of Schizomycetes. Cohn divides 
the bacteria into four tribes, comprising six 
genera : — 
1. The Spherobacteria or globular B. 
2. The Microbacteria or rod B. 
3. The Desmobacteria or filamentous B. 
4, The Spirobacteria or Spiral B. 
We will return to this classification. 
In 1874, M. Th. Billroth, in his researches upon 
the Coccobacteria septica, expressed opinions en- 
tirely different from those of Cohn. According 
to Billroth, the bacteria differ considerably in 
form according to the medium in which they are 
placed and divers circumstances. He claims that 
they constitute but a single species, the Coccobac- 
teria septica. This vegetable organism can pre- 
sent itself under the form of globular articles 
(coccos) or under that of rods (bacterie). These 
two forms may reproduce themselves by becoming 
elongated and dividing transversely, or may pass 
the one into the other. Buillroth claims to have 
found both forms united in a single filament, a 
