DEVELOPMENT OF EXOGENOUS SPECIES OF AGARICS 47 
As soon as the young ridges begin to form, certain deeply staining 
elements make their appearance among the unstained ones of the 
original palisade (figs. 89 and 99). They grow rapidly and soon 
outstrip the others. Later on (figs. 91-95, 100) the unstained elements 
become completely lost amongst the deeply stained ones, which 
appear now to be young basidia. Is it not possible that the earlier 
unstained hyphae represent sterile paraphyses? A somewhat similar 
condition in Cortinarius cinnamomeus (15, Plate XI, fig. 48) suggests 
a like interpretation for the thin zone on the outside of the deeply 
stained hyphae. In the median section of this later series (fig. 91) 
we see the surface view of one of the primary gills. It is interesting 
to note that the palisade layer formed on the stem is developing into 
the decurrent tooth of the gill. Figures 92-95 represent longitudinal 
sections of the same fruit body. As one progresses outward, secondary 
salients are now making their appearance between the primary ones. 
Figure 100 is an enlargement of a portion of figure 94 and shows the 
young basidia pushing out from the surface of the gill just previous to 
the development of the sterigmata and spores. In figures 96 and 97 
the fruit body is practically mature. 
Entoloma grayanum Pk. 
(Figs. 101-120) 
Early Stages. — The development of E. grayanum may be con- 
sidered somewhat more briefly, inasmuch as it follows very closely 
the method of development described for E. flavifolium. The youngest 
button (fig. loi) has already become sufficiently well differentiated 
to make distinguishable the primordial regions of stem and pileus. 
On the surface there is also a layer of tissue which appears to result 
from the disorganization of the superficial cells, indicating an early 
stage in the retreat of pileus development from the surface to the 
interior of the young fruit body. The hyphae making up the fruit 
body are very compact and take the stain with the greatest difficulty. 
As the plant increases in size, its tissues become more open and the 
irregular primordium of the hymenophore makes its appearance in 
the groove formed by the arching out of the pileus (figs. 103-105). 
This very soon becomes organized into the even palisade layer shown 
in figures 106-110, which becomes very compact and remains incon- 
spicuously stained (fig. no) as in the former species. 
