1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCETES 363 



Brief comparative summary of the above views on the 

 phytogeny of the Ascomycetes. — The adherents to the doc- 

 trine of the red algal origin of the Ascomycetes interpret the 

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

 highly developed 'Hrichogyne" (sterilized archicarp) of the 

 Collema type with red algae like certain of the existing forms, 

 Nemalion, or some of the higher forms in the vicinity of Har- 

 veyella, etc.; second, sac fungi with highly developed 

 * * trichogyne " (^ 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- 

 senting the stock from which both groups originated. 



According to the two first interpretations the sac fungi 

 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 fungi it is far more reasonable to search for one 

 in another fungus line, where, in the light of present-day 

 knowledge, there are known forms with sexual organs very 

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

 Ascomycetes. But we are not yet in a position to name any 

 known phycomycete^ as a probable ancestor of the Ascomy- 

 cetes, though it appears very likely that the ancestral stock 

 possessed phycomycetous characters. 



^ 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. 



