. Plant studies; an elementary botany. Botany. THE GREAT GEOUPS OF 259 and reddish-brown) making them very attractive. They show the greatest variety of forms, branching filaments, ribbons, and filmy plates prevailing, sometimes branching very profusely and delicately, and resembling mosses of fine texture (Figs. 222, 223, 224, 225, 226). The differen- tiation of the thallus into root and stem and leaf-like struc- tures is also common, as in the Brown Algae. 174. Reproduction.—Eed Algas are very peculiar in both their asexual and sexual reproduction. A sporangium pro- duces just four ase
. Plant studies; an elementary botany. Botany. THE GREAT GEOUPS OF 259 and reddish-brown) making them very attractive. They show the greatest variety of forms, branching filaments, ribbons, and filmy plates prevailing, sometimes branching very profusely and delicately, and resembling mosses of fine texture (Figs. 222, 223, 224, 225, 226). The differen- tiation of the thallus into root and stem and leaf-like struc- tures is also common, as in the Brown Algae. 174. Reproduction.—Eed Algas are very peculiar in both their asexual and sexual reproduction. A sporangium pro- duces just four asexual spores, but they have no cilia and no power of motion. They can not be called zoospores, *<}' therefore, and as each spo-. Fig. 227. A red alga (Cattithamnion). show- ing sporangium (A), aDd the tetraspores discharged (B).—After Thuret. Fig. 22K. A red alga (?7matton) ; A, sexual branches, showing antheri- dia (a), oogonium (o) with its trich- ogyne (7). to which are attached two spermatia Is); B, beginning of a cystocarp (o), the trichogyne (t) still showing; C. an almostmature cys- tocarp (d), with the disorganizing trichogyne it).—After Knt. rangium always produces just four, they have been called tetraspores (Fig. 227). Eed Algse are also heterog- amous, but the sexual process has been so much and so variously modified that it is very poorly understood. The antheridia (Fig. 228, A, a) develop sperms which, like the tetraspores, have no cilia and no power of motion. To dis-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
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