312 



THE LOWER FUNGI— PHYCOMYCETES 



be related to Endomyces its ascomycetous character is still in 

 doubt. 



In recent years another genus has been described which 

 seems to fall near Dipodascus. It has been studied by Betts 

 (1912) and Claussen (1921) and bears the name Pericystis Betts. 

 It is based on a single species P. alvei Betts occurring in hives 

 of bees, where it causes a well known trouble termed chalk brood. 

 The fungus is heterothallic, and a multispored globose sac is 

 formed by the copulation of a pair of gametangia much as in 

 Dipodascus. The nuclear history is not known, but in general 

 aspect the fungus seems to be intermediate in type between 

 Dipodascus, Endogone, and Eremascus (Eidam, 1883). Its cyto- 

 logical study should prove very interesting. 



Fig. 112.- — Dipodasctis albidus Lagerheim. (a) Young progametangia. (b) 

 Fusion of gametangia. (c) Female gametangium showing fusion nucleus. 

 (d) Young ascus. (e) Mature ascus containing spores, (6, after Lagerheim; 

 c, after Juel; others from material.) 



All the members of the Hemiascomycetes, as that group was 

 conceived by Schroter, have now been discussed. The ascomyce- 

 tous character of several of these is much in doubt, but until 

 further investigation is carried on none of them may be placed 

 with complete assurance in the Phycomycetes. Only a few may 

 be regarded as constituting connecting forms between the two 

 groups. Of these Dipodascus albidus is the most unquestioned. 



Recently Gaumann (1926) has presented a scheme of classi- 

 fication in which the Ascomycetes are split into the two major 

 subdivisions Hemiascomycetes and Euascomycetes. In his 

 grouping the Hemiascomycetes include two orders, the Endomy- 

 cetales, embracing the Dipodascaceae, Endomycetaceae, and 

 Saccharomycetaceae, and the Exoascales, incorporating the 

 Protomycetaceae and the Exoascaceae. Immediately above 



