No. IO.] FRESH-WATER ALGJE. II 



family have a disagreeable odor, giving rise to unpleasant 

 odors and tastes in drinking-water. 

 There are two orders, as follows : 



Order I. COCCOGONE.E. Plants unicellular or colonial, 

 not truly filamentous ; commonly embedded in a gelatinous ma- 

 trix, more rarely free-floating. 



Order II. HORMOGONE.E. Plants filamentous ; filaments 

 single or branched, generally consisting of one or more rows 

 of cells within a sheath, attached to a substratum, or free- 

 floating. 



ORDER I. COCCOGONE^E. 



The Coccogonese, the lowest form of the Algae, are 

 unicellular or colonial. The colonies vary much in size and 

 shape, and the cells, which are of various forms, are disposed 

 in a variety of ways in the usually hyaline and structureless 

 envelope. Multiplication is usually by simple cell division. 

 Rounded asexual spores have been found in some species, 

 formed inside the wall of the mother-cell. 



FAMILY I. CHROOCOCCACE-fE. 



This family is composed of unicellular forms of Algae which 

 divide and form daughter-cells ; often many generations are 

 involved in one mucilaginous envelope. The envelope varies 

 from firm and lamellose to hyaline and diffluent. The cells 

 often contain red, orange, or violet pigments. The members 

 of this family have been thought to be stages of filamentous 

 Algse, and Wolle so regarded them ; but more recent algologists 

 give them a distinct place of their own. 



Key to Genera. 



i. Cell division in only one direction 2 



Cell division in two directions at right angles, form- 

 ing plate-shaped or irregular masses . .Merismopedia* 

 Cell division alternate in the three directions of space 4 

 2. Cells with thin membrane, without a gelatinous or 

 mucous envelope, single or hanging together in 

 thick rows Sxnechococcus 



