102 WISCONSIN PHYTOPLANKTON 



Lemmermann follows Wille in placing the alga as a synonym of 

 Braun's old genus Gloeococcus but I prefer to follow G. S. West's 

 practice and consider the two genera distinct. The ordinary vegetative 

 condition is easily recognized but the rather rare palmella stage may be 

 mistaken for one of the limnetic Tetraspora species. 



TETRASPORA Link 1809. 



Colonies macroscopic or microscopic ; attached or free-floating ; gelat- 

 inous ; spherical, cylindrical, expanded, or variously lobed. Cells spher- 

 ical, generally in groups of four towards the periphery of the homo- 

 geneous, hyaline, gelatinous colonial envelope. Sometimes irregularly 

 distributed within the gelatinous colonial envelope. Chloroplast cup- 

 shaped, parietal ; sometimes diffuse ; with one pyrenoid. Each cell with 

 two or four long, hyaline, gelatinous bristles (pseudocilia). 



Asexual reproduction by the direct metamorphosis of vegetative cells 

 into biciliate zoospores. 



Sexual reproduction by a division of vegetative cells to form 4r-8 

 bilciliate zoogametes that fuse in pairs. 



TETRASPORA LACUSTRIS Lemmermann. PL 19, Figs. 5-6. 



Bot. Cent. 76: 152. 1898; Forschungsbr. a. d. Biol. Stat. zu Plon 7: 118, pi. I, 

 fig. 13. 189'9. 



Colonies microscopic; spherical, elongate, or irregular in shape; al- 

 ways free-floating. Cells spherical, generally in groups of four and 

 with pseudocilia 6-8 times as long as the diameter of the cell. Chloro- 

 plast single, cup-shaped, and parietal ; with or without pyrenoids. (Eu- 

 planktont). 



Diam. cells 7-10 p.; diam. colonies up to 300 p.. 



Crawling Stone (sss), Fence (rrr), Long (3) (sss), Mud (2) (sss), Pike 

 (rrr). 



Small colonies frequently resemble palmella stages of Spliaerocystis 

 Schroeteri but Tetraspora may be recognized by the pseudocilia. In 

 case of doubt it is always advisable to stain with safranin to bring out 

 the pseudocilia. 



GLOEOCYSTOPSIS G. M. Smith 1916. 



Cells elongate-cylindrical, with rounded ends and more or less curved. 

 Cells aggregated in fours or eights within a homogeneous gelatinous 

 sheath. Colonies spherical to ovoid and composed of an indefinite num- 

 ber of these aggregates. Colony not enclosed by a gelatinous sheath. 



