Lutman—Life History and Cytology of the Smuts. 1199 
however, trace the origin of the binucleated cells in the develop¬ 
ment of the carpophore. 
The fusion of the two nuclei in the basidium and the later di¬ 
vision of the fusion nucleus has been followed in great detail by 
Wager, Maire, Ruhland, Juel and others. The division to form 
the four nuclei which pass into the basidiospores is supposed to 
be the reduction division. 
Harper (21) was able in Hypochnus to trace a series of bi¬ 
nucleated cells from the hymenium back into the mycelium in 
the sub-stratum. 
Neither Maire or Harper found the origin of the binucleated 
cells. Miss Nichols (32) working on this problem came to the 
conclusion that in some species the mycelium becomes multi- 
nucleated, very soon after the spore germinates. She found no 
definite point at which the multi-nucleated condition of the cells 
passed over into the binucleated condition. 
The binucleated condition of the young ascus has been re¬ 
cently shown by Maire (31) to extend in Galactinia succosa into 
the ascogenous hyphae in the sub-hymenium for several cells at 
least. This would seem to indicate that the binucleated condi¬ 
tion in this species at least is working back into the earlier cells 
of the sporophyte. 
Several of the yeasts show conjugations similar to those of 
the conidia or promycelial cells of the smuts. Barker (1) has 
described two cells of Zygosaccharomyces Barkeri as fusing, the 
nuclei also fuse and then eight endospores are formed. Guiller- 
mond (17, 18) has further described such nuclear and cytoplas¬ 
mic fusions in a number of species of yeasts in some of which it 
occurs prior to spore formation while in others the spores fuse 
on germinating. 
The difficulty in working out the nuclear phenomena in the 
entire life cycle of the smut is very great. The saprophytic 
parts of it are in most cases easier to get than the parasitic 
stages, especially the earlier stages of parasitism. It is fre¬ 
quently difficult to detect the fungus in the host until it is too 
late to find out much about mycelial conditions especially in 
those species in which the mycelium simply breaks up into the 
