. Botany for high schools and colleges. Botany. Fio;. 206.—Vertical section of a small portion of the thalius of Col- lema Jacobcefolium,, showing the colorless* branching and jointed hy- phffi, the Nostoc-like gonidla, and a speimagoninm, from which sperma- tia are escaping. Magnified.—After Tulasne. 398.—Until Stahl's researches* showed the existence of sexual organs in CoUema, they were entirely unknown among lichens. He discovered, deeply imbedded in the tissue of tJie plantj an organ composed of a spirally coiled hypha-branch, and a Ycrtical septate portion, which rises to, and projects a
. Botany for high schools and colleges. Botany. Fio;. 206.—Vertical section of a small portion of the thalius of Col- lema Jacobcefolium,, showing the colorless* branching and jointed hy- phffi, the Nostoc-like gonidla, and a speimagoninm, from which sperma- tia are escaping. Magnified.—After Tulasne. 398.—Until Stahl's researches* showed the existence of sexual organs in CoUema, they were entirely unknown among lichens. He discovered, deeply imbedded in the tissue of tJie plantj an organ composed of a spirally coiled hypha-branch, and a Ycrtical septate portion, which rises to, and projects above, the surface; the spirally coiled por- tion he called the ascogonium, and the vertical portion the tri- chogyne. The whole he regarded as a species of carpogonium (Fig. 207, A, c, and d). He observed spermatia adhering to the pro- jecting portion of the tricho- gyne ; some of these united them- selves to the trichogyne by means of a tube" {C, Fig. 207). The result of this coalescence was the withering and disap- pearance of the cells of the tricho- gyne, and the growth and devel- opment of the as- cogonium. The latter process takes I^lace as follows : '' The cells of the ascogonium first of all increase in size, and then undergo -,. . Fig. 207.—Sexnal organs of Collema microphyllvm. A, division ; as a re- section of thallns; rt, a, hyphaj; b,b, the Nostoc-like If -P +1^' +V. gonidia ; c. ascogonium;(?, the exserted trichogyne. B^ suit 01 tniS, tne the spermatia, &, surrounding the exserted trichogyne, a. Qm'ral Qwann-nvYionf ^' coalescence of a spermatium, b, with trichogyne. bpirai aiiangement ah the figures magnified, B and (7 much more than A.— of the cells be- ^ft^^^stahi. comes less and less conspicuous, for the cells gradually sepa- * " Ueber die Geschleclitliclie Fortpflanzung der Collemaceen," 1877 (On the Sexual Organs of the Collemaceae). A brief synopsis of Stahl's results appeared in the Qr. Jour, of Mic. Science, October, 1878.
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