1902] BINUCLEATE CELLS IN HYMENOMYCETES 5 
readily isolated and show a basipetal habit of branching, very 
well represented in the figure (737, p. 301) of De Bary’s Hand- 
book (4). The successive development of such erect hyphae and 
their becoming interwoven and pressed together results in the for- 
mation of the hymenial layer. At first these erect fertile hyphae 
can be readily isolated and studied in the living condition, as was 
done by the older authors, the entire system of branches from a 
single main trunk being thus very easily and accurately worked 
out, as shown so well in the figure referred to above. In stained 
sections, too, these earlier tree-like fertile branches stand out 
with beautiful distinctness, and show basidia in all stages of 
development, and with their nuclei in all conditions. The order 
of succession in the development of the basidia can be traced 
with perfect accuracy. Later, as the hymenial layer becomes more 
dense, these individual twig systems can be no longer differen- 
tiated, though there is no question that the further development 
consists in nothing more than the pushing up of additional erect 
hyphal branches among those earlier developed. The species 
investigated forms a delicate frost-like growth on the surface of 
very well rotted logs, and should be collected in damp weather. 
The substratum was so soft as to offer no special resistance in 
cutting, and it was therefore possible to take off thin slices of 
the substratum several millimeters square and fix them with 
practically no disturbance of the fungus. 
The mycelium was found ramifying through the decayed 
wood cells in all directions. The peculiar clamp connections, 
described by Hoffman (7) between adjacent cells of a hypha, 
were abundant. In fact, they seemed to be present at one or 
both ends of nearly every cell. Brefeld (1) has described these 
clamps in Coprinus as originating in a tube which pushes out 
from the end of one cell, bends over, and fuses with the end of 
the next adjacent cell. Brefeld finds that before the clamp 
tube fuses with the second cell it is separated from its parent 
cell by aseptum. Later he finds also that a second septum is 
put in, replacing the walls broken down in the fusion. The 
mature clamp is thus cut off by a septum from each of the two 
