REPRODUCTION OF THE LICHENS. 441 



Koiber), the aseogoiiia are formed in immediate proximity 

 to the sperniogonia, but in other respects they resemble 

 those of Collema, and their subsequent history is the same. 



It appears from these observations that tlie development 

 of the apothecia of lichens is the result of the fertilisation of 

 carpogonia by means of spermatia. CoUema pulposum 

 affords nej^ative evidence in support of this statement, for in 

 large thalli of this Lichen Stahl was unable to find any 

 sperniogonia, and at the same time he failed to detect any 

 indications of developing apothecia. His investigation of 

 Syiiechoblastus concjlomeratus , of Leptogium Hildenbrandii 

 and microscopicum, and of such heteromerous lichens as 

 Parmelia stellaris and puherulenta completely confirmed 

 the above conclusions. 



The resemblance existing between the apothecia of lichens 

 and the fructifications of ascomycetous fungi had long been 

 remarked. Now that the development of the apothecia has 

 been completely traced, and their origin from the colourless 

 filaments only of the thallus (except in so far as the gonidia 

 of the thallus give rise to hymenial gonidia) has been placed 

 beyond doubt, there is sufficient evidence to justify a classifi- 

 cation which places lichens among the Ascomycetes in the 

 class Carposporeae. Collateral evidence is obtained by a 

 comparison of the mode of fertilisation of the carpogonia of 

 liihens with that of the Floridea. In both groups the sexual 

 cells are completely differentiated, and in both the male 

 cells are not motile. Stahl very naturally suggests the 

 propriety of calling the male cells of the Florideae not 

 anlherozoids, but spermatia. 



The evident sexuality of the lichens has an important 

 bearing upon the vexed question of the sexuality of the 

 Avhole group of the Ascomycetes, to which they are now 

 attached. The carpogonium of Ascobolus furfuraceus'^ , one 

 of the Discomycetes, resembles in some respects that of 

 Collema, and the resemblance of the ascogonium of 

 Eurotium" and of Sordaria^ to that of Collema is most 

 striking, but the carpogonium of the lichen is peculiar in that 

 it possesses a trichogyne. In the above-mentioned Ascomy- 

 cetes fertilisation is effected not by spermatia, but by a kind 

 of conjugation of the ascogonium with another filament, the 



^ Janczewski, " Morph. Uuters. ijb. Ascobolus furfuraceus." 'Bot. 

 Zeitir.,' 1871. 



^ De Baiy, 'Eurotium, etc., nebst Bemerkungen iiber die Gescblecli s- 

 organe der Ascomyceteu,' 1870. 



' Gilkinet, ' Kech. Morphol. sur les Pyreaomycetes,' J, Sordariees, 1874:. 



