170 PHYCOMYCETEAE 



tion below that of the Mucoraceae, but the occurrence of sporangioles 

 which are reduced to conidia in some forms would suggest a higher posi- 

 tion. This is also indicated by the formation of a dense hyphal protective 

 coat around the base of the sporangiophore in some species and around 

 the zygospores which are formed much as in Piloholus. Of the several 

 genera assigned to this family Moriierella is the only one that has been 

 fairly well studied. In addition to the spherical, many-spored sporangia 

 there occur in some species indehiscent, monosporous sporangioles ("con- 

 idia" or "stylospores"). The thirty or more species are mostly sapro- 

 phytic on vegetable matter or are weak parasites. In Haplosporangium 

 the main sporangiophores are more or less prostrate, septate and con- 

 stricted at the septa. From these segments arise tapering lateral branches 

 bearing terminally or also laterally one-spored sporangioles (in one 

 species) or two-spored sporangioles in H. bisporale Thaxter. No large 

 sporangia are produced and sexual reproduction is unknown. Dissophora 

 resembles a racemosely branched Mortierella. (Figs. 49, 58.) 



Family Endogonaceae. The twenty-six or more species at present 

 included in this family are grouped together on the basis of their sporo- 

 carps. These are loose or moderately firm sclerotium-like bodies a few 

 millimeters to 2-3 centimeters in diameter and produced in humus-rich 

 soil, leaf mold or among mosses. The interwoven hyphae are coenocytic 

 with occasional septa in the old hyphae. Scattered throughout the sporo- 

 carp are three types of reproductive bodies, but never all three in the 

 same sporocarp. In two species there are numerous sporangia. They have 

 a transverse basal septum as in Mortierella. They contain from 4-12 

 spores in one species and many spores in the other. In a dozen or more 

 species the reproductive bodies are thick-walled chlamydospores of var- 

 ious shapes and sizes. Some authors consider these to be azygospores. 

 True sporangia are entirely lacking. In a few species only zygospores are 

 formed in much the same manner as in Piptocephalis, with the suspensors 

 parallel and the zygospore budding out of the united gametangia or out of 

 the larger of the two. According to Bucholtz (1912) in Endogone lactiflua 

 Berkeley most of the numerous nuclei in each gametangium degenerate 

 leaving only one privileged nucleus and these unite in the zygospore. 

 Atkinson (1918) reports that in E. sphagnophila Atk. many pairs of 

 nuclei unite. In E. fasciculata Thaxter and E. occidentalis Kanouse both 

 chlamydospores and zygospores are present in the sporocarp. Miss 

 Walker (1923) obtained E. 7nalleola Harkness in pure culture and pro- 

 cured mycelial growth and sporangia of the Mortierella type but no sporo- 

 carps were produced nor chlamydospores nor zygospores. Miss Kanouse 

 (1936) succeeded in obtaining a culture from some of the mycelium in a 

 not quite mature sporocarp of E. sphagnophila. This produced a Mucor- 

 like mycelium bearing numerous sporangiophores and very closely re- 



