300 



BOTANY. 



398. Until StahFs researches* showed the existence of 

 sexual organs in Collema, they were entirely unknown among 

 lichens. He discovered, deeply 

 imbedded in the tissue of the 

 plant, an organ composed of a 

 spirally coiled hypha- branch, and 

 a vertical 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 



Fig. 20fi.-Vertical section of 

 mall 



1 portion of the thallus of Col- 

 Uma Jacobcefolium, showing the 

 colorless branching and jointed hy- gpemiatia adhering to the pro- 

 phse, the Nostoc-like gonidia, and a i -r 



spermagonium, from which gperma- lecting portion of the tricho- 

 tfa are escaping. Magnified.-After J 



Tuiasne. gy n e ; 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 

 place as follows : 

 " The cells of the 

 ascogonium first of 

 all increase in size, 

 and then undergo 



,. . . Fig. 207. Sexual organs of Colleina >ntcrophyllvm. A, 



division ; as a re- section of thalli..-*; a. a, hyphte: ft, b, the Notoc-like 



suit of this, 



crrvifnl t- U, coalescence or a gpermatitim, 



spiral arrangement A ii the figures magnified, B and c 



of the cells be- After8t hl - 



comes less and less conspicuous, for the cells gradually sepa- 



* " Ueber die Geschlechtliche Fortpflanzunjf der Collemaceen," 1877 

 (On the Sexual Organs of tin- Colleni in-a-). A brief synopsis of Stahl's 

 results appeared in the Qr. Jour, of Mic. Science, October, 1878. 



,-, gor.idia ; c. ascogonium ; <7, the exst-rted trichogyne. B, 

 tne the spermatia, b, surrounding theexMTted trichoayae, a. 

 coalescence of a Bpermatium, 6, with trichogyne, a. 

 - a much more than A 



