HOW TO KNOW THE FRESH-WATER ALGAE 



427a (421) Cells globose, or hemispherical because oi recent cell di- 

 vision 428 



427b Cells some other shape 441 



428a Cells inclosed in mucilage and bearing a long gelatinous hair. 

 See Fig. 206 GLOEOCHAETE 



428b Cells not in a sheath which bears a hair 429 



429a Protoplasts occurring as bright blue-green, vermiform bodies, medi- 

 ately arranged or scattered within Oocystis-like cells (see Oocy- 

 sts, Fig. 85), inclosed by mother-cell wall. See Fig. 208 



GLAUCOCYST1S 



429b Cells not as above. 



430 



430a Cells solitary or grouped in small families of 2-4-8 (rarely as many 

 as 16) individuals, if more than 16, then in a flat plate 431 



430b Cells aggregate in larger numbers, inclosed by a mucilaginous 

 sheath 435 



431a Cells solitary or in pairs, without a gelatinous sheath. Fig. 312. 

 SYNECHOCYST1S 



Fig. 312. Synechocystis aquatilis Sauv. 



This is a rather rare species which is prob- 

 ably of more common occurrence than is evi- 

 denced by the records of it from this country. 

 There are globular cells, solitary or in pairs, 

 without a mucilaginous sheath being appar- 

 ent. The densely granular 'central' body of 

 the cells is more complex than for other gen- 

 era in the Chroococcaceae. 



Figure 312 



431b Cells inclosed by a mucilaginous sheath (sometimes indistinct). 

 432 



178 



