128 TUFTS COLLEGE STUDIES, VOL,. II, No. 3 



i. Cells united in colonies. 2. 



2. Colonies of various form, cells motile when free, sometimes when 



in colonies. 3. TETRASPORACEAE. 



2. Colonies spherical, ovoid, or disk-shape ; cells normally always 



motile. 2. VOI/VOCACEAE. 



Family i. CHLAMYDOMONADACEAE. 

 Cells free, globose, ovoid, fusiform, or subcylindrical, rarely 

 attached by gelatinous threads, with 2 or 4 cilia ; chromato- 

 phore thick, cup-shaped, sometimes more or less split, with or 

 without one or more pyrenoids ; asexual reproduction by zo- 

 ospores, 2-8 formed in a vegetative cell, and similar to it in 

 form and structure, increasing to the normal size after leaving 

 the mother cell ; also by akinetes ; sexual reproduction by 

 gametes, similar to the zoospores, but usually smaller, some- 

 times 64 in a cell, in some cases with thick membrane ; in some 

 cases the male gametes are smaller than the female ; by the 

 copulation a spherical zygote is produced, usually red in color. 

 When germinating it becomes green and produces asexual 

 zoospores, in the same way as do the vegetative cells. 



KEY TO THE GENERA OK CHLAMYDOMONADACEAE. 

 i. Cells fusiform. 3. CHLOROGONIUM. 



i. Cells spherical to ovoid. 2. 



2. Protoplasmic threads passing through the cell wall. 



2. HAEMATOCOCCUS. 



2. No protoplasmic threads in cell wall. i. CHLAMYDOMONAS. 



i. CHLAMYDOMONAS Ehrenberg, 1833, p. 288. 



Cells globose, ovoid, or subcylindrical, with 2-4 cilia issuing 

 from the same point ; cell with thin, soft, rather close coating ; 

 chromatophore with one or more pyrenoids, and usually a red 

 stigma ; asexual reproduction by repeated division, usually 

 succeeded by the loss of cilia, or taking place during a Palm- 

 ella-stage ; sexual reproduction either between similar gametes, 

 or between male and female aplanospores. Fig. 13. 



Chlamydomonas forms are undoubtedly common in America, 

 as elsewhere, but little is really known as to their identity with 

 European species, which themselves are by no means all clearly 

 established. De Toni, 1889, gives 6 species with some detail, 

 and 10 "species minus notatae." Wille, 1900, notes that the 

 genus contains about 6 species, but does not name them ; 1903, 

 he gives 26 accepted and 23 doubtful species, of which very few 

 coincide with species described by De Toni. Wolle, 1887, 

 mentions as American, three species, one of them new. Miss 



