526 
W. H. SAWYER. JR. 
left when the former became differentiated from the primordial tissue, 
loosens, probably because of partial cessation of growth, and forms 
a thin layer with many interhyphal spaces extending over the surface 
of the pileus (figs. 17 and 19). As the plant approaches maturity the 
erect hyphae of the universal veil (figs. 18, 19) become aggregated into 
little tufts or clumps that form the erect, dark scales covering stem and 
pileus, so characteristic of this species. 
A peculiar and interesting feature of the blematogen is its double 
character over the margin of the pileus, as shown in the left side of 
figure 14 and in figure 15. The outer layer is characteristic of the 
universal veil elsewhere on the plant, being composed of large, thick- 
walled cells that radiate outward in loose arrangement. The inner 
portion, however, is very different in appearance. The hyphae are 
slender, with abundant protoplasm and thin walls. Instead of grow- 
ing outward in loose structure they lie closely side by side and passing 
up over the edge of the pileus margin become ingrown with the pileus 
surface an appreciable distance above its free edge. Kniep (10) has 
demonstrated that in hyphal threads bearing clamp connections, the 
growing end always lies in the direction in which the obtuse angle, 
formed by the junction of the cross wall of the hypha and the cross 
wall of the clamp, opens. These inner blematogen hyphae bear nu- 
merous clamp connections, whose walls all form angles opening upward ; 
therefore these hyphae could not have grown down from the pileus, 
but must have had an upward direction of growth. Furthermore, in 
the section shown in figure 16, the free ends of some of these hyphae 
may be seen interlacing with the threads of the pileus surface just above 
the margin of the latter. It is probable that the growth of this inner 
layer is slow, and its union with the pileus is due to the active outward 
and downward growth of the hyphae belonging to the latter, which 
interweave with the threads of the former. A duplex blematogen has 
been described by Miss Douglas in Cortinarius anfractus and C. ar- 
miUatus (8), differing, however, from the condition here in that the 
outer layer in these two species is thin and compact, while the inner 
part is loose and floccose. 
The Marginal Veil 
The marginal veil is very poorly developed in this species, as com- 
pared with Agaricus rodmani (5), Armillaria mellea (3), Agaricus 
comtnlus (2), species of Hypholoma (i), and other species. After the 
