MU COR ALES 



267 



possessing an envelope, it shows an essential relationship with 

 species of the Piptocephalaceae. The zygospores and chlamydo- 

 spores have never been seen to germinate, but sporangial ger- 

 mination has been observed (Walker, 1923: 245). The genus has 

 been considerably misunderstood, the term ascus having been 

 apphed to the sporangium as well as to the zygospore and 

 chlamydospore by various authors. Atkinson (1918: 1) regarded 

 the genus as constituting an interesting type between the Zygo- 

 mycetes and the Protoascomycetes, and states that it affords 



Fig. 96. — Endoyone upp. (a) Zygospore; its origin from gametangia, and 

 enveloping hyphae of sporocarp (fruit body) shown, (b-f) Stages in zygospore 

 formation, (g) Portion of sporocarp in section showing peridium and spores, 

 some of the latter immature. {After Thaxter 1922.) 



strong evidence of the Phycomycete ancestry of the Ascomycetes. 

 The genera Sphaerocreas, Sclerocystis, and Glaziella, known only 

 in the chlamydospore condition, resemble the chlamydospore- 

 producing species of Endogone sufficiently to indicate a relation- 

 ship between the various genera. They differ chiefly in minor 

 structural features of the fruit body. Whether these four 

 genera should be regarded as constituting a separate family 

 of the Mucorales related to and somewhat higher than the 

 Mortierellaceae is perhaps open to question, but in the present 

 state of knowledge it seems very likely that the group should 

 be incorporated in the Mucorales. 



