SYSTEMATIC AND DESCRIPTIVE. 333 



Here we may add some little-known species, which 

 possibly belong to this group. 



Sphserotilus natans. Cells 4 9 /* long, 3 p thick, 



united in a gelatinous sheath to form threads. The cells 

 comprise rods and cocci-forms ; the cocci are set free, and 

 develop into rods, which again form threads. In the last a 

 false branching has been observed. The plasma of the 

 cells breaks up into minute, strongly refractive portions, 

 which develop into round spores, at first of a red, and 

 afterwards a brown colour. They occur in stagnant and 

 flowing water contaminated with organic matter, and form 

 floating flakes of a white, yellow, rust-red, or a yellow- 

 brown colour. 



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 //, in diameter, singly or heaped into slimy drops on 

 water in which algae are decomposing. 



Spiromonas volubilis, Perty. Colourless, trans- 

 parent cells, 15 1 8 fju long. Rapidly motile and revolving 

 round a longitudinal axis. They occur in marsh water and 

 putrefying infusions. 



Spiromonas Cohnii. Colourless cells, consisting 

 of i^ spirals, with both ends acutely pointed and provided 

 with a flagellum. Breadth of the cells 1-2 4 p. They 

 occur in water containing decomposing matter. 



The following species is described last, so that it may 

 stand between the cladothrix group of bacteria and the 

 hyphomycetous fungi given in the appendix which 

 follows. It is attached provisionally to the former for 

 reasons stated below, but there is need for further inves- 

 tigation before its position is established, as there is still 

 some doubt as to the true life-history of the fungus. 



