PHYCOMYCETOUS AFFINITIES 307 



spores having been obtained. Juel (1921) attempts to homolo- 

 gize the chlamydospore in this group with the fertile cells of 

 the ascogenous layer in the Exoascaceae. Gaumann (1926) 

 and Gaumann and Dodge (1928), following this conception, 

 embrace the two families in the single order Exoascales. To the 

 author there seems to be no justification for this point of view, 

 inasmuch as the spore sac of Taphrina and Exoascus is clearly 

 an ascus of a high type. As treated here the Protomycetaceae 

 are regarded as of unknown relationship. They may represent 

 an isolated hne of development with a phycomycetous ancestry, 

 but there is no sure basis for their inclusion in the Ascomycetes. 

 Until their nuclear history is better understood it would be futile 

 to attempt to treat the group more definitely. 



Of the famihes included by Schroter in the Hemiascomycetes 

 the Ascoideaceae alone remain for consideration. Two genera 

 Dipodascus Lagerheim (1892) and Ascoidea Brefeld (1891) were 

 incorporated in the family by Schroter, two others, Oscarhrefeldia 

 Holtermann (1898: 6) and Conidiascus Holtermann (1898: 23), 

 were added by Lindau. There is insufficient evidence to show 

 that any two of these four genera are in fact closely related. 



The genus Dipodascus was based on a single species and is 

 still monotypic. This species, D. alhidus Lagerheim, was first 

 discovered by its author in Ecuador growing in a shme flux from 

 one of the Bromeliaceae. He obtained it in pure culture, and 

 studied it in the living state. Nine years later it was found 

 again by Juel (1902 a) in Sweden, where it occurred in a similar 

 exudation from a wounded birch. Apparently only these two 

 widely isolated collections have been made. Subcultures from 

 Juel's material were widely distributed, and the fungus was 

 studied in many institutions. The writer carried it in culture 

 through many transfers over a period of years, but it has now 

 died out, and is apparently no longer available in culture else- 

 where. Probably it is not uncommon in nature, but if reisolated 

 it should again be made widely available. 



The fungus forms a white mat of profusely branching, septate 

 hyphae, composed of multinucleate cells. At the tips of some 

 branches oval, unicellular, multinucleate, hyaline oidia are 

 formed. A definite sexual process occurs, numerous gametangia 

 being formed over the mycelium. The gametangia arise in 

 pairs as short lateral outgrowths from adjacent cells of the same 

 hypha, or are cut off as terminal cells on different hyphae. In 



