1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCETES 



363 



comparative summary 



the 



b 



views on the 



phytogeny 



the A 



The adherents to the doc 



of the red algal origin of the Ascomycetes interpret the 

 of contact in three different ways : first, sac fungi with 



highly developed 



(sterilized archicarp) of the 



Collema tvDe with red aljrae like certain of the existing forms 



Nemalion. or some of the higher forms 



veyella, etc. ; second 



sac 



fnng 



with 



highly 



;y of Har- 

 developed 



trichogy 



sterilized archicarp) of the Poly stigma 



type with hypothetical trichogyne algae representing the com- 

 mon stock for the origin of both groups ; third, sac fungi with 

 simple generalized copulating gametes of the Gymnoascus 

 type with hypothetical algae having a simple procarp repre- 



& 



the stock from which both 



.-> 



According to 



the two fi 



interpretat 



ginated. 



the sac fung 



have been derived through highly developed and specialized 

 forms from either quite highly developed and specialized red 

 algae, or both groups from a common trichogyne algal stock, 

 and then by degeneration have slid backward from complex 

 and specialized structures to simple, generalized and primi- 

 tive ones. The third view which recognizes a simple procarp, 

 without regard to a trichogyne, as the important character of 

 the hypothetical stock, is far more comprehensible. 



But if we must go back to some hypothetical ancestor, which 

 cannot be represented by any known red alga, for the source 

 of the sac funeri it is far more reasonable to search for one 



& 



m 



another fungus line, where, in 



arc known forms 



the light of 



day 



ledge, there 



much like the sexual organs of simple, known forms of the 



A 



But we are not vet in a position to name 



known phycomycete 1 as a probable ancestor of the A 

 cetes, though it appears very likely that the ancestral stock 

 possessed phycomycetous characters. 



x Lotsy ('07) suggests Cystopus; Miss Dale ('03) in her study of Gymnoascus 

 suggests Basidiobolus; Nienburg ('14), Monoblepharis; while Dangeard ('07) 



suggests Myzocytium vermicolum as the prototype of the higher fungi. 



