. Fecundation in plants. Plant embryology; Plants, Sex in; Karyokinesis. COLLEMA. 127 gyne are smaller in diameter than those of the ascogonium, and their number varies in the species examined from six to twenty-four, A sharp demarkation between trichogyne and ascogonium does not exist. The end of the trichogyne which projects above the surface of the thallus is generally short and cylin- drical or flask-shaped. In rare cases it ends in two short and nearly equal branches. The free surface of this end cell is covered by a viscid sub- stance which facilitates the adherence of the spermatia that
. Fecundation in plants. Plant embryology; Plants, Sex in; Karyokinesis. COLLEMA. 127 gyne are smaller in diameter than those of the ascogonium, and their number varies in the species examined from six to twenty-four, A sharp demarkation between trichogyne and ascogonium does not exist. The end of the trichogyne which projects above the surface of the thallus is generally short and cylin- drical or flask-shaped. In rare cases it ends in two short and nearly equal branches. The free surface of this end cell is covered by a viscid sub- stance which facilitates the adherence of the spermatia that escape in large numbers during moist weather from the flask-shaped male organs, the spermagonia. Baur ('98), who studied Collema crispum, confirms Stahl's observa- tions, and gives additional informa- tion concerning details of cell struc- ture. The terminal cell of the trich- ogyne in Collema crispum, which projects above the surface of the thallus, is much larger than the other cells of this organ, being longer, somewhat swollen at the middle, and terminating in a point (Fig. 50, B). It is also provided with a viscid coating. Each cell of the entire carpogo- nium possesses a nucleus of the typi- cal structure. The transverse walls between the cells are not broken down, though each reveals a small pit, such as is present in the trans- verse septa of vegetative hyphae. In four cases Baur found empty spermatia attached to the end of the trichogyne, whose cells showed the same signs of degeneration described by Stahl. The cells in the upper part were collapsed, the cross-walls much swollen, and no nuclei could be seen in them. The septa between the lower cells of the trichogyne were clearly broken down. Each cell of the ascogonium contains at first one nucleus, and since each gives rise to ascogenous. Fig. 50.—Carpogonium of Collema crispum, (After Baur.) A, mature carpogonium; trichogyne ends in large receptive cell which projects above surface of thallus. B, receptive cell w
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