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 (Micro- 

 coccus) and the microbacteria (Bacterium) which 

 are found in this state. 



The filiform bacteria and the spirilla are never 

 found in gelatinous masses (Cohn). Kay-Lankes- 

 ter, however, claims to have met the Spirillum 

 tenue, in the form of zoogloea, and Klein the Spi- 

 rillum undula and rosaceum (Warming). 



The form of Zoogloea , properly so called, gelat- 

 inous and thick, has never been found by Warm- 

 ing in infusions of sea-water. 



According to the terminology of Billroth the 

 zooglcea are called gliacoccos and glidbacteria 

 (from yXi'a, mucus substance). 



3. Form of My coder ma. 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 zooglcea, 

 but differs from it by the absence of the interme- 

 diary mucous 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. 



