ATKINSON: THE GENUS ENDOGONE 13 



Empusa iEntomopthora) fresenii, Empusa rhizospora, sepulchralis, etc., 

 Endogone sphagnophila and lactiflua. 



4. Progression in the direction of selection of sex nuclei. In 

 Endogone lactiflua one sex nucleus is selected from among all the 

 potential ones in each gamete. This illustrates how the situation in 

 Dipodascus, Eremascus fertilis and in Endomyces has arisen. This 

 situation is presaged in some of the lower zygomycetes in the degener- 

 ation of some of the gamete nuclei in Rhizopus, Sporodinia and Zygo- 

 rhynchtis, if w^e may accept the account by Moreau (191 1, 1913). 

 In Endogone sphagnophila there are many potential and many func- 

 tional nuclei in the gametangia and these are carried on into the 

 young germinating, or progressive zygote. This type illustrates a 

 situation which has been retained in those ascomycetes with multi- 

 nucleate gametangia as in Monascus, the Gymnoascaceae, Ascodesmis, 

 Pyronema, etc. 



5. The postponement or moving forward of the moment of nuclear 

 fusion from the gametangia to the new outgrowth, or progressive 

 zygote. The examples are the same as those given in paragraph 3. 

 In the zygomycete alliance Endogone lactiflua represents the most 

 progressive stage in these directions of any known species, unless 

 Dipodascus should be regarded as a phycomycete. The sex pair of 

 nuclei is organized by the migration of the antheridial nucleus into 

 the oogone. The pair then migrates into the new outgrowth where 

 the sex nuclei lie side by side in the resting zygote, or fuse, in one 

 variety. As Bucholtz (1912) points out there is wanting here only 

 the conjugate division of the nuclear pair to parallel the situation in 

 the ascogenous hyphae of the true ascomycetes. 



From the situation reached by progression in these directions, by 

 members of the zygomycete alliance, there is but a small gap over 

 which to bridge in reaching the protoascomycetes. The principal 

 steps may be indicated as follows: 



1. Free cell sporulation of the progressive zygote of Endogone. 

 This alone would place this zygote in the category of a generalized 

 ascus, and Endogone would become a fit member of the protoascomy- 

 cetes. Intersporal substance present in the sporangium of some 

 phycomycetes during sporulation may possibly presage typical free cell 

 sporulation. Other steps toward the true ascomycetes are indicated 

 in the following. 



2. The omission of a period of rest by the progressive zygote and 

 the immediate free cell sporulation of the same. This step alone 

 would reach the level of Dipodascus, Eremascus, Endomyces magnusii, 

 etc. 



3. Vegetative growth of the zygote and postponement of free cell 



