£902 | BINUCLEATE CELLS IN HYMENOMYCETES It 
The cells of the old hymenium, like those of the mycelium 
buried in the substratum, contain regularly two nuclei. These 
are usually placed rather close together, as noted above. The 
apical cells which are to form basidia contain regularly two, and 
only two, nuclei. I have found no exceptions to this rule, 
. though doubtless such occur as abnormalities, as. pointed out by 
Maire. The young basidium is also regularly separated from 
its stalk cell at an early stage, so that in Hypochnus there is no 
chance for such a migration of pairs of nuclei as Wager thinks 
probable. The conditions are especially favorable in Hypoch- 
nus for determining this point. In the subhymenial tissue of 
the agarics the hyphae are so densely packed, in many cases 
forming a pseudo-parenchyma, that it is difficult to trace the 
path of asingle hypha for any distance, or to determine just 
what the connections of the basidium at its base may be. In 
Hypochnus the loose branching makes it possible to determine 
just how and when each basidium has been formed and cut off, 
and it is certain for this case that Maire’s general statement that 
two, and only two, nuclei are cut off in the young basidium is 
true, as opposed to those of Rosen (13) and Wager (16). The 
stalk cells also contain two nuclei. The conditions just 
described are well illustrated in figs. 2, 3, and 7. 
Whether the two nuclei of the cell from which the basidium 
is cut off divide simultaneously, and whether simultaneous 
nuclear division (‘‘conjugate nuclear division” of Poirault and 
Raciborski [12]) occurs generally in the formation of new cells 
in the mycelium, I have been unable to determine with certainty. 
That this is the rule in the case of the binucleated cells of the 
rusts there can be no doubt. The work of Dangeard and Sappin- 
Trouffy (3) and Poirault and Raciborski (12) establishes this 
fact and I have been able to confirm for myself their results on 
this point. As to the details of the so-called conjugate division, 
however, the figures so far must be considered as very unsatisfac- 
tory. The evidence presented by Sappin-Trouffy and by Poirault 
and Raciborski is not at all convincing on any points further 
than that the nuclei lie side by side and divide simultaneously. 
