122 
Mycologia 
thickness above and below the cavity, but at this stage when the 
hymenium begins to form in the ceiling of the cavity, as it were, 
the portion above becomes thicker while the portion below (the 
volva) becomes thinner. Peck (3) says this portion above the 
pore-bearing layer is in two strata, an outer thicker one and an 
inner thin stratum. Just when these strata of the fundamental 
tissue are differentiated is not known. In these later stages an 
appendage appears inside of the volva and protruding from 
around the hymenophore. This has been figured by Peck (3) 
and is imperfectly shown in some of the sections in the accom- 
panying plate. It is probable that this appendage is not a con- 
stant characteristic. In some specimens it does not extend wholly 
around the hymenophore but forms irregular, tuberculose projec- 
tions. In other specimens it appears as a very low ridge encir- 
cling the pore-bearing layer. As the volva becomes thinner, it 
grows downward in the portion near the attachment of the sporo- 
phore. Here it becomes very thin and the ostiole of the volva 
is formed. This is always very close to the tree trunk. 
Until nearly the time when the ostiole is formed, the whole 
sporophore is very fleshy and water}\ Now it begins to shrink 
somewhat by the loss of water and the texture becomes soft- 
corky and still of a white color. The tubes become yellowish to 
almost cinnamon. The shrinking of the whole sporophore causes 
a cracking of the resinous crust, which often scales off. In the 
old sporophores this leaves the Avhite surface glabrous, but often 
anastomosingly rimose. The development of the sporophore as 
observed from free-hand sections is illustrated by the series of 
median vertical sections on plate 159, while the mature sporo- 
phores with well-developed ostioles are shown on the same plate. 
More detailed work on the development of this peculiar poly- 
pore should be done to determine the histological development 
and formation of (a) the primordium of the pore-cavity, (&) the 
primordium of the hymenium, (c) the thin interior stratum of the 
sporophore, of which the appendage mentioned above is the pro- 
jecting edge, (d) the constancy of this projecting appendage, 
and (e) the ostiole of the volva. 
Pure cultures of the fungus were made from the tissue of the 
young sporophores. Potato hard agar was used as a medium. 
