642 



THE PHYLOGENY OF THE FUNGI 



have considered, it must be settled by further studies upon the various 

 types of sporangia in the Phycomyceteae and different groups of algae. 

 In the Phycomycetous hypothesis of the origin of the Ascomyceteae 

 there is presented the difficulty of accounting for the production of the 

 nonmotile sperms and of the trichogynes. Apparently very early in the 

 development of the Phycomyceteae sexual reproduction took place by the 



IN THESE THREE GROUPS OCCUR FORMS WITH 



FREE SPERMS AND TRICHOGYNES 



\ \ "LECANORALES 



PEZIZALES.ETC. 



( 



ERYSIPHALES 



MONASCACEAE 



ASPERGILLACEAE 



GYMNOASCACEAE 



ENDOMYCETACEAE 



ASCOIDEACEAE 



MUCORALES 



SPHAERIALES, PSEUDO- 

 SPHAERIALES, ETC. 



MYRIANGIACEAE 



ELAPHOMYCETACEAE. ETC. 



SACCHAROMYCETACEAE 



Fig. 207. Suggested lines of evolution within the 

 Ascomyceteae, following in the main the ideas of 

 Dangeard, Atkinson, Gaumann, Mez, et al. (After 

 Bessey: Mycologia, 34(4) -.355-379.) 



union of two equal-sized motile gametes, as in some of the Chytridiales 

 and Blastocladiales, by the union of two motile gametes of unequal size, as 

 in some species of Allomyces, or by the union of a flagellate sperm with a 

 nonflagellate egg, as in Monohlepharis. In all the other Phycomyceteae in 

 which sexual reproduction is known, this occurs by the union of two non- 

 motile cells (Olpidiopsis) or by the passage of nuclei and cytoplasm from 

 one gametangium to another one through a simple opening or through a 

 conjugation tube. In Dipodascus, Endomyccs, and most of the forms con- 



