THE GREEN ALGAE OF NORTH AMERICA 137 



production by cell division in all directions, cells separating 

 or joined in small families, forming irregular gelatinous masses ; 

 also by akinetes and by ordinary cells developing cilia and be- 

 coming motile ; sexual reproduction by biciliate gametes. 



A genus in which have been included at various times a mul- 

 titude of forms which had no character in common but that of 

 single cells contained in a general gelatinous mass. Many of 

 these supposed species have been found to be stages of growth 

 of Ulothrix, Chaetophora and other genera ; indeed a Palmella- 

 stage is recognized in the development of a large part of the 

 green algae. Only one species can now be considered as a dis- 

 tinct organism in itself. 



P. MINIATA lyeiblein, 1830, p. 338; Wolle, 1887, p. 193, PL 

 CLXII, fig. 10 ; Chodat, 1894, p. 587, PL XXII, figs. 1-15. 

 Cells varying much in size, 3-40 //. diam., colored by haemato- 

 chrome, orange-, brick-, or blood-red, or yellow, solitary or 

 united 2-8, forming irregular gelatinous masses ; membrane 

 thick, hyaline, more or less distinctly lamellate, diffluent ; spor- 

 angia 10-12 /u. diam., each producing 4-8 zoospores ; or a single 

 cell developing to a biciliate zoospore-like form ; sexual repro- 

 duction by gametes similar to the smaller zoospores. In moist 

 places, generally distributed. Fig. 23. Europe. 



Var. AEOUALIS Nageli, 1848, p. 67, PL IV. D, fig. 2 ; Wolle, 

 1887, p. 193, PL CLXII, fig. 10 ; P. B.-A., No. 1314. Cells of 

 nearly uniform size, 12-15 P- diam.; color brick-red, easily 

 changing to green ; wall thinner and less distinctly lamellate 

 than in the type. Cal. Europe. 



2. BOTRYOCOCCUS Kiitzing, 1849, p. 892. 



Cells ovoid-cuneate with rounded ends, radiately arranged in 

 rounded colonies, united in botryoidal masses by a gelatinous 

 coating, free or attached. Chromatophore covering the cell 

 wall, without pyrenoid ; asexual reproduction by cells becom- 

 ing biciliate and motile ; they soon come to rest, divide, and 

 take a red color ; in these cells gametes are formed, which by 

 conjugation form a spherical zygospore, whose further develop- 

 is unknown. 



B. BRAUNII Kiitzing, 1849, p. 892 ; Wolle, 1887, p. 195, PL 

 CXXIV, figs. 1-4; P. B.-A., Nos. 263, 1177. Family about 

 i mm. diam., botryoidal and more or less lobed, at first green, 

 later brownish-red ; cells ovoid or irregular, about 6 ^ diam. 

 Floating in stagnant fresh water. Fig. 24. Mass., N. J., Cal. 



Europe. 



