442 SYDNEY H. Vines. 



polHnodiuin ; coiif?eqiiently the formation of a trichogyne is 

 unnecessary. 



Doubt has, however, been cast upon this interpretation of 

 the coalescence of these two filaments. Van Tieghem ' 

 considers that, in Eurotium at any rate, this apparently 

 sexual act is merely an instance of a coalescence of hyphal 

 filaments which is by no means uncommon, and his observa- 

 tions upon Chsetotnium lead him to conclude that not only 

 is such a coalescence unnecessary for the formation of a 

 fructification, but that it tends rather to prevent it. Brefeld^ 

 also pronounces against the sexuality of the Ascomycetes. 

 He found that ascogenous hyphse removed from the deve- 

 loping fructification and cultivated in solutions of salts did 

 not form asci, but simply grew out into ordinary hyphal 

 branches. Stahl, in reply to Brefeld's arguments, points 

 out that the development of the one generation from the 

 other is not necessarily connected with the formation of 

 sexual cells or of spores. In mosses, for instance, Stahl ^ 

 and Pringsheim* have shown that the cells of the sporogoniam 

 will, under certain circumstances, grow out into protonemal 

 filaments upon which new moss-plants are developed. Here 

 the transition from the one generation (sporophore) to the 

 other (oophore) is effected independently of the spores. In 

 the ferns it appears, from the researches of Farlow,^ that the 

 prothallus (oophore) may produce a young fern (sporophore) 

 by simple budding without any formation of archegonia. 

 These facts suffice to overthrow the argument founded by 

 Brefeld upon his observations. 



The forms of ascomycetous fungi, studied by Van Tieghem 

 and by Brefeld (Peziza, Morchella), apparently do not 

 present that distinct origin from separate groups of hyphse 

 of the para[)hyses and of the asci, which is so prominent a 

 feature in the development of the apothecium of a lichen, 

 and their sexual organs are undeveloped. In the lichens, 

 and some other Ascomycetes, which may be regarded as 

 being the most perfectly developed forms of this group, the 

 evident differentiation accom{)an.ying the first ftnination of 

 the apothecium is accompanied by a well-marked sexuality. 



' ' Sur le dev. du fuit des ChtBtomcuiu et la prcLeudue scxualile des 

 Ascomycetes,' JS76. 



- '• Die Eutwickeluiigsgescliichte der Basidiomycetcii." ' Bot. Zeit., 

 1876. 



' " Ueb. Protonemabilduug aa dem Sporosoiiium der Laubiiioose." 

 ' Bot. Zeilg.,' 1876. 



* " Ueb. Sprossung der Moosfriichle, &c." * Jahrb. f. Wiss. Bot.,* 

 1877. 



* See this Journal, vol. xiv, 1874. 



