. A handbook of cryptogamic botany. Cryptogams. 4)8 PROTOPHYTA Fig. 349.—Boiryo- coccus Braunii Kt2. ( X 400).. Fig. 350. — Urococcits instgnis Hass. (x 400). (From nature.) Botryococcus Ktz. consists of mulberry-like masses of thick-walled cells united together into colonies, with no investing membrane, or only a very slight one ; it is found in bog-pools, and is endowed with a rotating as,well as a free-swimming motion. It has possibly a genetic affinity with the Coenobiese. In Urococcus Hass. the endo- chrome is bright red, and the cell- walls throw off successive layers of mucilage, which
. A handbook of cryptogamic botany. Cryptogams. 4)8 PROTOPHYTA Fig. 349.—Boiryo- coccus Braunii Kt2. ( X 400).. Fig. 350. — Urococcits instgnis Hass. (x 400). (From nature.) Botryococcus Ktz. consists of mulberry-like masses of thick-walled cells united together into colonies, with no investing membrane, or only a very slight one ; it is found in bog-pools, and is endowed with a rotating as,well as a free-swimming motion. It has possibly a genetic affinity with the Coenobiese. In Urococcus Hass. the endo- chrome is bright red, and the cell- walls throw off successive layers of mucilage, which form together a cylindrical or fusiform stalk, com- posed, in some species, of a large number of distinct annular segments. Tetraspora Lk. is composed of cells associated together in large numbers in a single layer imbedded in a copious gelatinous envelope. It has no spontaneous motion, and is possibly allied to Merismopedia, and also appears to have affinities with the Ulvaceae. Gay (Bull. Soc. Bot. France, 1886, Sess. Extraord., p. 41) records in T. gelatinosa (Desv.) the formation of biciliated zoospores, one being produced from the contents of each cell, and afterwards becoming encysted into a resting-spore. In Palmodictyon Ktz. the gelatinous envelope is filiform and branched, and cell-division takes place chiefly in two directions only. The position of the following genera is very uncertain. Very little is known of their mode of reproduction, and they lack the copious gelatinous envelope which is characteristic of the family gene- rally. They are mostly but feebly endowed with spontaneous move- ments, and may probably be a resting condition of algse or protophytes classed under entirely different groups. Raphidium Ktz. includes several species very common in fresh water, and consisting of very narrow fusiform acuminate cells, usually curved, solitary or joined together in bundles, the cells being in the latter case united by their middle, Cell-division takes place in
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