CHAPTER V. TYPE OF THE ASCOMYCETES AND 



RHODOPHYCE^E. 



Within recent years our knowledge of the sexual process in certain 

 of the higher fungi, the Ascomycetcs, has been greatly advanced by 

 the classical researches of Harper. These researches have inaugurated 

 a sort of renaissance in the study of the sexual process in the fungi ; 

 for within the last decade the doctrine of sexuality in the Ascomycetes 

 as advanced by De Bary has been strenuously denied in some 

 quarters, especially among the mycologists of the Brefeldian school, 

 and the view that no sexual reproduction at all occurs in this group 

 had gained considerable ground. 



Harper's work upon certain Perisporeacece and Discomycetes leave 

 no doubt concerning the true sexual process in those groups, and it is 

 reasonable to expect that further research will bring to light the 

 presence of sexual reproduction in other genera in which the existence 

 of sexuality seems far more questionable. 



In the development of the sexual organs and in the behavior of the 

 egg-cell, there is represented here a type of sexual reproduction very 

 different from that known in other fungi and in the green algae. The 

 closest parallel is found in the Rhodophycece and in certain lichens. 

 There is certainly a striking and suggestive resemblance between the 

 structure of the sexual organs and the process of development subse- 

 quent to fecundation in Spharotheca, Pyronema and Collema on the 

 one hand, and in such forms of the red algae as Batrachospermum 

 and Nemalion on the other. It is not improbable that further research 

 will reveal a tolerably well connected series from forms like Sp/iczro- 

 theca to the remarkably complex Diidresnya, and we may accept 

 without much reserve the view that the great groups to which these 

 representatives belong represent related phylogenetic series. In this 

 chapter, therefore, I shall present the sexual process in Sphcerotheca, 

 Pyronema, Collema, Batrachospermum and Dudresnya as repre- 

 sentative of the type of sexuality in the Ascomycetes, including that 

 form in lichens, and in the Florideae. 



What follows concerning Sphcerotheca and Pyronema is based 

 exclusively upon the studies of Harper ('95, '96, 1900). 



SPH^ROTHECA. 



Both antheridia and oogonia of Sphcerotheca arise as lateral branches 

 of neighboring mycelial filaments, the development of the oogonium 



