10 BROOKLYN BOTANIC GARDEN MEMOIRS 
there is first a nuclear fusion in pairs, perhaps some of the nuclei 
degenerating. If this is confirmed the situation in E. sphagnophila 
agrees in this respect with that in the Mucorales. It appears also that 
later, when the nuclei lie in a peripheral zone, they undergo at least 
one division. At the present stage of the investigation the possibility 
is not excluded that fusion of nuclear pairs does not occur. It is also 
possible that after the division of the nuclei in the peripheral zone of 
the zygote all but two may degenerate, the two selected ones later 
uniting to form the fusion nucleus. This would bring E. sphagnophila 
more nearly in line with the process in EF. lactiflua as described by 
Bucholtz, the selection of the sex nuclei being postponed to a late 
period in E. sphagnophila. I do not think, however, that this is the 
case, but am inclined rather to believe that there is multinuclear fusion 
in pairs,’ similar to that which takes place in the Mucorales as de- 
scribed by Gruber (1901) in Sporodinia, by Dangeard (1906) in Sporo- 
dinia, and by Moreau (1911-1913) in Rhizopus, Zygorhyncus and 
Sporodinia. That in certain species of Endogone there is fusion of 
but one pair of sex nuclei in the zygote, while in other species there 
may be fusion of several pairs of sex nuclei, is not incomprehensible 
in view of the nuclear process in fertilization in Cystopus (See Stevens 
1899, 1901), where in C. bliti and portulacae there are fusions of many 
pairs of sex nuclei in the egg, while in other species there is fusion of a 
single pair of sex nuclei. 
There is another feature in EF. lactiflua which is paralleled in 
certain of the Zygomycetes. This is the hyphal envelope which 
encloses each zygote. Crude tendencies to such an envelope are 
present in Phycomyces and Absidia of the Mucorales and in Empusa 
rhizospora of the Entomophthorales (Thaxter, 1888), while in Mor- 
tierella there is a well-developed envelope. In no other species of 
Endogone, however, is such an envelope around each zygote known, 
not even a rudimentary one. In this respect LE. lactiflua represents a 
more advanced stage of evolution, which is manifested also in the 
origin of the resting zygote as a distinct outgrowth of the larger 
gametange. This species may possibly represent the type of a distinct 
genus, so widely does it depart in these two respects from all the 
other known species. 
There is another feature, however, in which Endogone departs 
widely from any other known phycomycete. The mycelium and 
numerous zygotes (‘‘resting’’ spores or ‘“‘sporangia’’ in the partheno- 
genetic species) are united into a compact and distinct fruit body, or 
° According to Leger (1896) in Sporodinia grandis, and according to Miss McCor- 
mick (1912) in Rhizopus nigricans, all nuclei but two degenerate in the zygote, but 
this has not been confirmed. 
