THE DEVELOPMENT OF SOME SPECIES OF AGARICS 229 
becomes older the hyphae are more loosely interwoven (Fig. 7). Its 
further growth is provided for by means of branching and elongation 
of its elements. 
Pileus Primordium. — At the time the stipe fundament is delimited 
from that of the pileus, the apical hyphae grow upward and spread 
out in all directions. In this feature it is similar to that of Clitopilus 
noveboracensis, which is described below. The hyphal elements are 
long, slender and terete. This is the pileus primordium (Fig. 84). 
By continued radial and diverging growth of its elements the pileus 
fundament increases in size (Figs. 72, 77). This gives rise to a hemi- 
spherical body which is delimited from the stipe by the annular groove 
(Figs. 72-74). Further epinastic growth causes the margin to curve 
inward toward the stipe (Fig. 76). At this time the plant has assumed 
a beautiful and symmetrical form. In Figure 77, the pileus has en- 
larged and the margin has become so strongly involute that the edge 
turns upward against the gills. The hyphae do not grow out from 
the margin of the pileus nearly so strongly as in Clitopilus novebora- 
censis. 
Hymenophore Primordium. — The hymenophore fundament is 
differentiated in the annular groove between the pileus and stipe and 
stains deeply. This area develops in a radial manner, following the 
centrifugal growth of the pileus, characteristic of the Agaricaceae. 
This area consists of short hyphae perpendicular to the surface of the 
annular groove. It becomes more dense by interpolation of new ele- 
ments which are formed by digitate branching of the primordial 
hyphae. 
Palisade Layer; Origin and Development of Primary Lamellae. — As 
the hymenophore becomes more compact by intercalary growth, the 
cells themselves increase in size. The end of the hyphae reach the 
same level and form an even palisade layer, as shown in Figure 78. 
A higher magnification is show^n in Figure 85. The hyphal elements 
that compose this layer are longer than those of the other species 
described in this paper, and are comparatively slender. 
As the elements increase in number and size, the resulting pressure 
is partly relieved by the level palisade layer bulging out into radial 
fold-like ridges. These ridges are the gill fundaments. In this 
species, as in Clitopilus noveboracensis, they occur first on the stipe 
very near the angle between the latter and the lower surface of the 
pileus (Fig. 79). Later the gill salients of the primary lamellae appear 
