56 MORPHOLOGY OF THE BACTERIA. 
one studies the inferior species. The only char- 
acter which appears general is the presence of 
chlorophyll in the algze and its absence in the 
fungi. But, if we adopt this distinctive character, 
and apply it in all its rigor, we are obliged to 
separate in the inferior alge some forms very 
nearly related, and which do not differ from their 
relations except in this particular. And this is ex- 
actly what happens in the case of the bacteria. 
In truth, the bacteria, although entirely with- 
out chlorophyll, have numerous affinities as to 
form, movement, etc., with the oscillatoriacee, 
and, according as one or the other of these char- 
acters have appeared to predominate, the bacteria 
have been classed as algee or as fungi. 
It is thus that Davaine, Rabenhorst, then Cohn, 
struck above all by the resemblance of form, mode 
of grouping, and of multiplication, have placed 
the bacteria among the algzw. Cohn insists, above 
all, upon the affinities of the filiform bacteria with 
the beggiatoa and the leptothrix ; of the micrococ- 
cus, and of the bacterium, with the chroococcacee. 
He at first placed them at the commencement of 
this last series; but we shall see further on that 
in his last publications he has disseminated them 
among the oscillatoriaceze and the chroococcaceex. 
Robin and Nageli, on the other hand, insist 
rather upon the affinities of the bacteria with the 
yeast plants, which are incontestably fungi, and 
they include them in this class. 
Robin says expressly: ‘“ All the corpuscles de- 
scribed under the name of Bacterium termo, B. 
