112 Thirty-eighth Report on the State Museum. 



The peculiar character of this genus, and otte which gives to it its 

 name, is the milky juice which pervades the flesh and especially the 

 lamellee 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 lamellae. 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. In some species of Mycena a 

 similar milky or colored juice exists, especially in the stem, but these 

 are abundantly distinct from the LactariLby 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 is 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 is 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 lamellae 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 in the 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. 



