SPECIES DESCRIBED BY VARIOUS WRITERS. 213 



Spirillum leucomelaneum, Koch. A rare 

 form observed in water covering rotting algse. 

 Dark and glass-like spaces alternate in the spi- 

 rillum, resulting from a regular arrangement of the 

 dark granular contents. 



Myconostoc gregarium, Cohn. The threads 

 are very thin, colourless, unarticulated, but fall 

 apart into short cylindrical links when dried. 

 They form gelatinous masses 10 17 /x, in diam. : 

 singly, or heaped into slimy drops on water in which 

 algse are decomposing. They have been considered 

 to be the zooglcea form of Spirillum unduia, and by 

 others a phase in the development of Cladothrix 

 dichotoma. 



Spiromonas volubilis, Perty. Colourless, 

 transparent cells, 15 18 /x, long. Rapidly motile, 

 and revolving round a longitudinal axis. They 

 occur in marsh water, and putrefying infusions. 



Spiromonas Cohnii. Colourless cells, con- 

 sisting of i \ spirals, with both ends acutely pointed 

 and provided with a flagellum. Breadth of the 

 cells 1*2 4 //,. They occur in water containing 

 decomposing matter. 



Monas vinosa. Round or oval cells of about 

 2 '5 /x in diam., often united in pairs. Their motion 

 is slow and tremulous, and the cell substance pale- 

 red, with dark grains interspersed. Flagella have 

 ngt been observed. They were observed in water 

 with decaying vegetable matter. 



Monas Okenii. Short cylindrical cells, 5 /u. 



