300 



BOTANY. 



398. — Until Stahl's researches* showed the existence of 

 sexual organs in Gollema, 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 

 Fig. 206.-Verficai section of a as a specics of carpogonium (Fig. , 

 Bmaflpoition of the thaiiiis of Col- ^07, A, c, and d). He observed/ 



lema Jacobatfohum, showing the ~" ' ' ^ ' "' / 



colorless branching and jointed hy- g-permatia adhering to the prO- 



phte, the Nostoc-like gomdia, and a r ^ ,n j_ • i 



speiTiagonimn, from which spernia- lectmg portion 01 the tricho- 



tia are escaping. 

 Tulasne, 



Magnified.— After 



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 

 place as follows : 

 " The cells of the 

 ascogonium first of 

 all increase in size, 

 and then undergo 



,. . . Fig. 207. — ^d'xnsXorga.n^ol CoUema Tnicrophyllvm. A f 



division ; as a re- section of thallns; a, a, hyphse ; ft, 6, the Nortoc-like- 



ij. jj XT,' 4.-U gor.idia ; c. ascogonium ; d, the exserted trichogyne. J5, 



SUltJ 01 tniS, tne the ppermatla, ft, surrounding the exsorted trlcliogyne, a. 



ov,i«„1 „««„«™„. J. 0, coalescence of a spermatinm, 6, with trichogyne. a. 



spiral arrangement a11 the figures magDifled, S and (7 much more than .A.— 



of the cells be- After Sta'il. 



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



* " Ueber die QescUlechtliche Fortpflanzung der Collemaceen," 1877 

 (On the Sexual Organs of the CoUemacese). A brief synopsis of Stahl's 

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



