172 PHYCOMYCETEAE 



Glaziella, produce only chlamydospores and differ from Endogone in their 

 arrangement in the sporocarp. To what family of Mucorales the Endo- 

 gonaceae are nearest is uncertain. The lack of columella in the sporangial 

 species has led some mycologists to suggest that the family is related to 

 the Mortierellaceae, especially since in E. lactiflua the enlarging zygo- 

 spore becomes surrounded, according to Bucholtz, by a tight weft of 

 hyphae as in Mortierella. This weft is lacking in E. sphagnophila in which 

 species the sporangium possesses a columella. Possibly the family is in 

 reality not monophyletic but represents an assemblage of more or less 

 unrelated species which agree only in the production of a sclerotium-like 

 sporocarp under certain environmental conditions. The earlier mycol- 

 ogists placed this family in various positions; among the Ascomyceteae, 

 in the Protomycetaceae, close to the Ustilaginaceae, etc., but Bucholtz 

 (1912) by his study of zygospore formation showed its affinity to be with 

 the Mucorales. (Fig. 59.) 



The genus Helicocephalum Thaxter (1891), with two or three species, 

 has the type of growth of Mucorales but whether it is related to any of 

 the foregoing families is uncertain until further study has been made 

 (see Drechsler, 1934). 



Order Entomophthorales. The Entomophthorales are fungi whose 

 mycelium is often much reduced. Upon germination of the spore the germ 

 tube is usually coenocytic but sooner or later septa appear which divide 

 it into plurinucleate or even uninucleate segments, forming a septate 

 mycelium in some genera or in other genera falling apart into the so-called 

 "hyphal bodies." These latter may multiply by fission. Of the five or 

 more genera two are saprophytic or rarely parasitic, one is parasitic in 

 the gametophytes of ferns, one in the Desmidiaceae, and the remainder 

 in the bodies of insects. The latter group includes the vast majority of 

 the known species of the order. Asexual reproduction is by means of 

 reduced sporangia (probably more properly sporangioles) which may be 

 uninucleate or plurinucleate and are shot off singly from the apex of a 

 somewhat club-shaped sporangiophore, except in the genus Massospora 

 in which they are produced internally in the body of the insect host. These 

 sporangia are usually called conidia, as in the homologous structures in 

 the Peronosporaceae and Mucorales. In many cases such a "conidium" 

 may produce another " conidiophore " and shoot off a secondary conidium, 

 and that may produce a tertiary conidium, and so on. The ultimate ger- 

 mination is by a germ tube except in the genus Basidiobolus in which 

 the conidium shows its true sporangial nature by producing internal 

 spores. Sexual reproduction is by the union of mycelial segments (or of 

 hyphal bodies) to form zygospores which may lie in one of the uniting 

 gametangia (Basidiobolus), between the suspensors (Conidiobolus), or later- 

 ally to the fusion cell or to one of the conjugating gametangia {Enlo- 



