40 
GERTRUDE E. DOUGLAS 
pileus grows very rapidly (fig. 2). Its texture is at first similar to 
that of the stem, since its hyphae, as mentioned above, are but the con- 
tinuation of those of the stem which have bent outward under the 
influence of epinasty. By growth and branching new elements are 
being continually added, especially at the margin of the pileus. When 
the primordium of the hymenophore appears, followed by the level 
palisade layer with its compact row of parallel hyphae, the pressure 
causes the subhymenophore tissue to become stretched, looser and 
more open in texture. We noticed in the earliest stage a layer of more 
deeply staining tissue over the surface of the fruit body (fig. i). It 
persists throughout the early stages and appears to be composed of 
enlarged hyphal cells (in fig. 6, 4 in diameter) which have been chem- 
ically changed or injured as they have grown through the substratum. 
They persist for a time in loose tufts, finally disappearing with the 
maturity of the plant. 
Development of the Stem. — As the plant grows, the stem elongates 
rapidly and at the same time grows in thickness by the interpolation 
of new elements, which intertwine with each other but which take a 
general longitudinal direction. On the surface they bend strongly 
outward (figs. 1-I3) instead of uniting to form a compact layer as 
they do in many forms with a smooth stem. The villous stipe of the 
young growing plants is due to this circumstance. 
Hygrophorus 
Collection and Preparation of Material. — Three species have been 
studied. The material used in the study of H. miniatus came from 
two different collections. Pieces of a decayed stump, containing 
young fruit bodies, were brought into the laboratory from McGowan's 
woods, near Ithaca, in October, 1915, and from these the young fruit 
bodies were chosen. Another collection was made by Mr. Blizzard 
at Seventh Lake, Adirondack Mts., N. Y., during August, 1916, 
from which the early stages in the development of the gills were 
obtained. The specimens of H. horealis were collected by Professor 
Atkinson and the author from rich leaf mold where numerous scat- 
tered mature plants were growing, in the sphagnum moor at Mallory- 
ville, N. Y., during August, 1914. H. fiitidtis plants were found grow- 
ing in rich soil by the edge of Eighth Lake, N. Y., in August, 1916. 
The material of all three species was fixed in medium chromo-acetic 
