THE FRESH-WATER ALGAE 1 49 



104 (103, 105, 106) Cells single, spherical, or oval. Dictyosphaerium Nageli. 



Chromatophore single, parietal. Reproduction by internal division. 

 Fig. 160. Dictyosphaerium pulchellum Wood. X 570. (Original.) 



105 (103, 104, 106) Colonies much as in Dictyosphaerium except that the cells 



are in clusters of four which are held together by the rem- 

 nants of the mother-membrane Tetracoccus West. 



Some regard this as a young stage in Dictyosphaerium. 



106 (103, 104, 105) Cells clustered, grape-like, imbedded in the rather firm, 



often yellow gelatinous strands. . . Botryococcus Kiitzing. 



'^r^^mftS^yVi West's genus Ineffigiata is probably a Botryococcus where the gelati- 



Xr> ^ A>vr\ K^Yp nous envelop is somewhat contracted. 



CyQ In old cultures of Botryococcus, and often in nature, an orange 



^5^2^ or reddish oil is produced which gives the cells that color. 



The alga is found very frequently in pools, ponds, and lakes; it 

 has been known to form the water bloom on lakes of small 

 dimensions. 



\^Y^ Fig. 161. Botryococcus braunii KJitzing. X about 300. (Original.) 



107 (96, 102) Cells not at the surface of a gelatinous mass but distributed 



through it 108 



108 (109) Colonies cyHndrical, branching; gelatinous envelop somewhat 



rigid and often lamellate Palmodictyon Nageli. 



, - Cells in groups of two and four, the groups sur- 



S Q ® ® ^ ^ o -' rounded by gelatinous vesicles which are united to 



® ® o® ^ '^ - ^ " "* form the cylindrical colony, and give a more or less 



^ ^--o^ o'*' netted appearance to the gelatinous portion. Repro- 



. duction by means of resting spores with brown walls; 



^ - ^ these spores germinate and produce a new colony. 



/ West states that the outer coat often becomes very 



^ ' © ^ . ~ tough and of a brown color. Palmodictyon is a 



\ 0^_^' very rare alga in America, but Collins reports it 



-^ ^3 '*' **o ''' from Massachusetts. 



••^ , "> ^^ ' ' Fig. 162. Palmodictyon viridis YMUing. X 210. 



,,^ (After West.) 



109 (108) Colonies of no definite shape, of the shape of the individual cells, or 



more or less angled and showing a dark gelatinous layer be- 

 tween the cells. Cells often isolated no 



110(127,128) Colonies irregular m 



111 (120) Cells not in clusters "2 



112 (lis) Gelatinous envelop containing concentric lamellae about the 



ceUs "3 



