[VOL. 2 



362 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



ascus in the entire group is a great obstacle in the way of 

 accepting a polyphyletic origin for the group. All things con- 

 sidered he is inclined to accept de Bary's view of their phy- 

 comycetous origin. 



The origin of the Ascomycetes from the Phycomycetes is 

 recognized by Dangeard ('07) through such forms in which 

 there is still a union of gametangia, Dipodascus and Ere- 

 mascus represent such forms in his scheme. The generalized 

 ascus resulting from the union of the gametangia of Dipo- 

 dascus he terms a ' ' sporogone. " From Eremascus, by re- 

 duction, forms like Endomyces arose, while the Ascomycetes 

 with ascogenous hyphae were derived from such forms as 

 Dipodascus by delayed nuclear fusion and the proliferation of 

 the gametangium into what he terms *'gametophores" (= as- 

 cogenous hyphae). The gametes then are formed in the 

 nuclear pair which fuses in the ascus. This terminology 

 arises from his persistent belief that the ascus is the egg. 

 Shorn of the change in terminology and his, perhaps, unfor- 

 tunate insistence on homologizing the ascus with the egg, his 

 interpretation of the relation which such a form as Dipodascus 

 bears to the Ascomycetes, has much merit. 



Nienburg ( '14) suggests the origin of the Ascomycetes from 

 the Phycomycetes through some such form as Monoblepharis. 

 He would find the evidence for this in the homology of the 

 archicarp of Poly stigma rubrum with such forms of Monoble- 

 pharis in which the stalk cell of the oogonium is an anther- 

 idium, and where the oogonium is terminated by one or more 

 sterile cells. The archicarp of Polystigma he interprets as 

 having two fertile cells at the base and prolonged into a long 

 sterile septate portion (so-called trichogyne) which forks, 

 sending a branch to either surface of the leaf. The basal 

 multinucleate cell is the antheridium. After pore formation 

 one nucleus migrates into the unicellular egg. Interesting as 

 this suggestion is, forms of Pythium (see de Bary, '81, '84; 

 Atkinson, '95) with intercalary oogonia and stalk antheridia 

 present a closer analogy to the archicarp of Polystigma as 

 described by Nienburg, but it is extremely doubtful if the 

 point of contact is to be sought through such structures. 



