ORGANIZATION OF THE BACTERIA. 45 
other, so as to leave between them greater inter- 
vals. The masses sometimes attain a diameter of 
several centimetres. 
The gelatinous substance in which the bacteria 
are included seems to be produced by a thicken- 
ing and jellification of this cell-membrane, or by a 
secretion from their protoplasm, but the latter 
view seems more plausible than the former (De 
Lanessan). 
It is commonly the spherical bacteria (JJicro- 
coccus) and the microbacteria (Bacteriwm) which 
are found in this state. 
The filiform bacteria and the spirilla are never 
found in gelatinous masses (Cohn). Ray-Lankes- 
ter, however, claims to have met the Spirilum 
tenue, in the form of zoogloea, and Klein the Syi- 
riullum undula and rosaceum (Warming). 
The form of Zooglea, properly so called, gelat- 
inous and thick, has never been found by Warm- 
ing in infusions of sea-waier. 
According to the terminology of Billroth the 
zoogloea are called gliacoccos and gliabacteria 
(from yAva, mucus substance). 
3. Form of Mycoderma. — In certain cases, the 
bacteria unite on the surface of the water, or of 
the liquid in which they are developed, to form a 
thick layer, a sort of membrane. This production 
called mycoderma by Pasteur is a sort of zooglea, 
but differs from it by the absence of the interme- 
diary mucus substance. The bacteria are, how- 
ever, motionless, although living, since they come 
to the surface to be in contact with oxygen, which 
is necessary to them. 
