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). Ray-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 

 zoogloea are called gliacoccos and glidbacteria 

 (from y\la, 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 zooglcea, 

 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. 



