460 BOTANICAL GAZETTE [NOVEMBER 
hymenophore primordium is perpendicular to the point of their origin, whether 
over the upper end of the stem, in the angle between stem and pileus, or on the 
undersurface of the pileus. Their course is parallel, although in the angle of the 
furrow there is more or less of a convergence in their growth direction. At 
first these hyphae are very slender and terete, but later they become stouter 
blunt. From the time of their origin they form a palisade layer whose 
surface is, in general, level until gill formation begins. In the majority of the 
species, the ends of the hyphae soon reach the same level. Their “register” 
is even, and the surface compact; but in Hygrophorus miniatus and H. nitidus 
the palisade for some time is not compact and the hyphae do not register evenly. 
The even register of the palisade hyphae is delayed in these species for some 
time after the origin of the gill salients 
During the early stages of aciooiiei of the hymenophore there is a 
strong epinastic growth of the pileus margin, causing it to curve downward and 
inward. This is particularly strong in most of the species, less so in Entoloma 
ais Didkoheork and less so in Hygrophorus nitidus. The gill salients are formed by 
the more rapid downward growth and extension of the subjacent tissue in 
regularly spaced radial areas. The development advances in a peripheral 
direction from the stem toward the margin of the pileus.. The growth direction 
is perpendicular to the morphological undersurface of the pileus, and the situa- 
tion from this oo can readily be understood when the pileus margin is 
wae incurv 
4 cables layer, which eventually becomes the hymenium, the ele- 
in are multiplied by branching of the subhymenial elements. In the 
species of Hygrophorus in particular, and to some extent also in Entoloma 
 ninhsine ei the pressure of the i i palisade loosens up the elements of 
a zone of less density. This peculiarity 
is well shown also i in Siphaks chrysophylla and Clitocybe cerussata studied by 
BLIZzZARD.? 
In both these papers dealing with gymnocarpous forms, it is shown that 
the origin and the general course of development of the hymenophore corre- 
sponds with that of angiocarpous forms of the Agaricus type. It is further 
shown that there is a tendency in the early stages of development for a supet- 
ficial zone of the pileus, here of quite limited extent, to be arrested in growth, 
sometimes quite regularly and normally. The regular course of development 
being thus shifted to a slightly interior zone presages the later evolutionary 
_ type of development presented by the angiocarpous forms, where the origin and 
differentiation of stipe and pileus primordia are shifted permanently to the 
interior of the young basidiocarp primordium, with a more or less well marked 
external zone, the blematogen.—Gro. F. ATKINSON 
* BuizzarpD, A. W., The development of some species of agarics. Amer. Joe 
Bot. 4:221-240. pls. 6-11. 1917. 
