OVERHOLTS: DIAGNOSES OF AMERICAN PortAs—II 251 
less than 3 u in diameter. The second form is more character- 
istic of the plant as it grows in more protected situations, 
and here the narrow rigid hyphae give place, entirely or in part, 
to wider and nearly simple hyphae 3-5 » in diameter (TEXT 
FIG. 3). But all sorts of intergrading conditions exist so that 
neither on these characters nor on any others can the two forms 
be kept distinct. Then in coloration there is a nearly white form 
characteristic of plants where protected from the light, a gray 
or pallid form where exposed to considerable illumination, and 
finally a bright colored form with almost egg yellow hymenium 
whose relation to light I have not determined. This last form 
is more rarely met. I have specimens of it from New Jersey, 
Georgia, and Illinois. Through all these variations the hymenial 
characters are very constant (PLATE 14, FIGS. 3, 4). Spores are 
usually found in abundance (TEXT FIG. 3), even in crushed prep- 
arations of the hymenium, and often have a collapsed and empty 
appearance. 
Fic. 3. PorRIA MEDULLA-PANIS (Pers.) Cooke. A, B, Hyphae showing 
variations in amount of branching and considerable variation in diameter, 
the narrow, much branched ones being characteristic of the xerophytic form 
of the species; C, Spores. 
The species is closely related to P. subacida Peck, which shows 
the same microscopic characters as the form of P. medulla-panis 
with the larger hyphae. Other microscopic characters possesse 
by both are the large basidia, the ellipsoid spores, and the 
abundance of crystals in the tramal tissue. Yet I have admitted 
here no specimens from a coniferous substratum, though perhaps 
the thick form referred to in a previous paper by me (Bull. N. Y. 
State Mus. 205-06: 114. 1919) should really be included here. 
