1902] BINUCLEATE CELLS IN HYMENOMYCETES 9 
apical basidium is more than half developed the cell beneath it 
pushes out a new baSidium (jig. ¢) which grows up beside the 
first. Later a second (fig. 3), and in some cases even a third, 
basidium may bud out on different sides and just beneath the 
basal wall of the first basidium. This gives the appearance ofa 
stalk cell bearing a cluster of basidia at its apex. Since these 
basidia are pushed out successively, however, and their formation 
consists essentially in a process of cell division, the whole clus- 
ter represents really a basipetal series. The stalk cell becomes 
successively, at least as far as the nuclei are concerned, the 
sister-cell of each developing basidium as it is cut off. At the 
same time, from cells below the stalk cell of the first basidium 
lateral branches may be given off and grow to a length of from 
one to several cells, according to the level at which they arise 
from the main axis. Still further branchlets may arise from the 
cells of these lateral branches. In the end the apical cells of 
all these branches become basidia, and just beneath the septa 
which cut off these basidia one or two further basidia bud out. 
The basidium terminating the main axis of such a system is 
always the oldest and ripens first. The clusters produced on 
the lateral branches push up to the height of the main ax's, but 
not higher, and ripen successively. The whole process is easily 
understood from a study of De Bary’s figure and figs. 2-4, 7, 9, 
ro. With reference to their method of branching, we may 
compare such hyphal systems with their basidia to a flat topped 
cyme among the flowering plants. 
The entire fruit body of Hypochnus is composed thus of a 
_ series of such cymosely branched hyphal systems, whose 
branches are intricately interlaced and packed together. Such 
a hymenium is strictly a compound structure made up of a 
series of similarly branching fertile hyphae. The only unity to 
be found in it lies in the fact of its possible origin from a single 
mycelium produced by the germination of a single basidiospore. 
As a matter of fact, it is highly improbable that such unity as 
this ever really exists in any given case. It is much more likely 
in the majority of cases that mycelia from different spores are 
