DEVELOPMENT OF EXOGENOUS SPECIES OF AGARICS 
41 
acid, cleared in cedar oil and embedded in 52° paraffine. Sections were 
cut from 5-7 microns in diameter and stained with basic fuchsin and 
carbol fuchsin. 
Hygrophorus miniatus Fr. 
(Figs. 25-47) 
Young Stages. — Fruit bodies up to i mm. in length show no differ- 
entiation of tissues (fig. 25). The buttons are more or less conical 
and composed of compactly interwoven hyphae about 1.5 in diameter 
with conspicuous nuclei. A number of the fruit bodies, in about this 
stage of development, show, distributed throughout the tissue, other 
hyphae which are considerably larger in diameter and which have a 
strong affinity for the stain. They are possibly in the process of 
disintegration or are food-storage hyphae. They are also found in 
vsome of the later stages but have completely disappeared by the 
time that the hymenophore primordium is organized. It was sug- 
gested by Professor Atkinson that they probably function as nutritive 
elements for the other rapidly growing hyphae. The young buttons 
elongate very rapidly and become flask-shaped with long, pointed necks. 
Differentiation of the Fundaments of Pileus, Stem and Hymenophore. 
— Later the fruit bodies undergo considerable broadening at the apex, 
leaving a decided groove, which separates the nearly oval pileus funda- 
ment from that of the elongate stem (fig. 26). In this latter region 
the primordium of the hymenophore later appears (fig. 27). The 
delineation of the pileus and the stem regions is not due to differences in 
the nature of their tissues but, as in the case of Mycena subalcalina, to 
the growth and rapid multiplication of the hyphae of the pileus funda- 
ment, which exhibit a strong tendency to turn outwards and down- 
wards. Certain ones at the top of the stem and on the under side of 
the pileus show this inclination more strongly than the others and 
become directed outward in a nearly perpendicular direction to the 
tissues from which they arise. They are narrower than the elements 
at the pileus margin, have sharp ends, and become very numerous by 
successive branching. These hyphae constitute the primordium of the 
hymenophore (fig. 27). 
Development of the Gills. — Differing from the condition found in 
the majority of forms, developing according to the Agaricus type, thus 
far studied, the appearance of gill salients precedes the formation of a 
definite, even palisade layer. While the elements of the primordium 
