112 THIRTY-EIGHTH REPORT ON THE STATE MUSEUM. 
The peculiar character of this genus, and one which gives to it its 
name, is the milky juice which pervades the flesh and especially the 
lamellze of the species. It is generally white, like milk, but in some 
species it quickly changes color on exposure to the air, and in a few 
it is always colored. In some instances it is colorless or watery, but 
such plants are regarded by Fries as degenerate or abnormal from 
growing in very wet places. In very old specimens, or in very dry 
weather, the milk is often more scant than usual, and it sometimes fails 
entirely. Its presence may generally be ascertained by cutting or break- 
ing the pileus or the lamellz. It is better to seek it in the latter, in- 
asmuch as it generally flows more freely from them, especially in small 
species, than from the pileus and stem. Insome species of Mycena a 
similar milky or colored juice exists, especially in the stem, but these 
are abundantly distinct from the Lactarii by their small size, campanu- 
late pileus and slender, hollow, cartilaginous stem. In the genus Russula 
the size, shape and texture of the species is the same as in Lactarius, 
but the milky juice is wanting, though the acrid taste may be present, 
so that the presence of the milk and the fleshy stem is sufficient to dis- 
tinguish these plants from all other Agaricini. 
The pileus is fleshy in all the species, but in some it is thin. Even 
when thick and compact its texture is brittle, so that it 1s easily broken. 
It is variegated in many species by more highly-colored concentric 
bands or zones, a character always wanting in the allied species of Rus- 
sula. The margin of the pileus 1s at first inflexed or involute, and the 
pileus itself more or less convex, but with advancing age the margin be- 
comes spreading or elevated, and then the pileus, being depressed in 
the center, presents an obconic or funnel shape. Sometimes the pileus 
is convex, but umbilicate or centrally depressed with its earliest appear- 
ance, in other instances it is broadly convex or nearly plane, and fur- 
nished with a small umbo or papilla. 
The lamellz are at first adnate, but by the change in the shape of the 
pileus, which comes from its expansion and the elevation of the margin, 
they become more or less decurrent. It is not uncommon to find them 
branched or forked, especially near the inner extremity. In color 
they are generally white or whitish, but this is often varied by yellowish 
or reddish tints as they become mature. ‘They often change color where 
cut or bruised, even when the milk remains unchangeable. In some 
species they become pruinose or dusted by the spores when old, in others 
they remain naked. 
The stem in many species is short and comparatively thick, in others 
its length equals or exceeds the diameter. of the pileus. It may be 
equal in diameter throughout its entire length, or become gradually 
narrower either toward the apex or toward the base. In some species 
it is always solid or merely becomes spongy within when old, in others 
it may be either spongy within or hollow, and that too in different indi- 
viduals of the same species. When it is stuffed in the young plant it is 
likely to be hollow inthe old. In many of the species individuals some- 
times occur in which it is eccentric. 
The spores are globose or broadly elliptical, and more or less rough 
or echinulate, and they vary but little in size in the different species. 
Still by their slight variations in size and color they sometimes afford 
good specific characters, and should by no means be neglected in the 
study of the species. 
