There is a species of Russula (R. emetica) very common in woods, easily recognized by its smooth scarlet top, white gills, and white stem and by its biting acridity, which, though recorded as poisonous by some authors, is considered edible by others. This mushroom, R. emetica, has been subjected to chemical analysis by Kobert, who finds in it muscarin, cholin, and pilz-atropin in varying proportions. Kobert states that in Germany it is "rightly" considered poisonous, though eaten in Russia, and ascribes the fact that it is not deemed poisonous in the latter country to the manner in which it is there prepared, the poisonous alkaloid being in greater part eliminated by parboiling the mushrooms, and not merely pouring off the water, but carefully squeezing it out of the parboiled fungi.
To the presence in this mushroom of the neutralizing alkaloid "pilz-atropin" in varying proportions may also be attributed in some measure the safety with which it has been eaten under certain conditions. R. fœtens and other acrid Russulas, as well as Lactars, have been known to produce severe gastro-enteritis.
Considering the foregoing, it would seem the part of prudence at least to avoid such of the Lactars and Russulas as have an acrid or peppery taste.
I think it would be a wise precaution to pour off the water of the first boiling in the case of all mushrooms about which there is a particle of doubt, whether recorded as poisonous or not.
Lactarius torminosus Fries. Cap fleshy, at first convex, then expanded, at length depressed in the center, slightly zoned, margin turned inwards, pale ochraceous yellow, with flesh-colored mottlings; downy or hairy; gills whitish, changing to pinkish yellow, narrow and close together; stem equal, stuffed or hollow, pallid or whitish; milk persistently white and acrid. In woods and fields. Specimens have been collected in New York, Massachusetts, Maryland, and Virginia. Cap 3 to 5 inches, stem 2½ to 4 inches.
Lactarius pyrogalus. Cap fleshy, slightly zoned, smooth, even, and moist, depressed in the center, grayish, or cinereous; gills white or yellowish, thin, not crowded; stem short, stout, stuffed, or hollow, sometimes slightly attenuated towards the root, pallid; flesh white or whitish; milk white and extremely acrid, copious. Borders of woods and meadows. This mushroom is sometimes called the "Fiery Milk Mushroom."
Lactarius uvidus Fries. Cap thin, convex, then plane, and slightly depressed in the center, sometimes showing slight umbo, viscid, zoneless, smooth, dingy gray or pallid brown, margin turned inwards; gills narrow and close together, white or yellowish, when cut or bruised turning a purplish hue; stem stuffed or hollow, viscid, smooth, equal or slightly tapering towards the cap, white; milk white, changing to lilac, acrid. Height 2 to 4 inches. Cap 2 to 4 inches broad. In woods.
Lactarius turpis Fries. Cap viscid, compact, zoneless, greenish umber, margin clothed with yellowish down; gills thin, paler than the cap; stem hollow or stuffed, stoutish, short, viscid, olive color, slightly attenuated towards the base; milk white, acrid. Fir woods.
Lactarius plumbeus Fries. Cap fleshy, firm, dry, somewhat hairy, varying in color, usually some shade of brown; gills yellowish, thin, and close together; stem solid, equal, lighter in color than the cap; flesh white; milk white and acrid.
Lactarius vellereus Fries. Fleecy Lactarius. Cap compact, convex or umbilicate, zoneless, minutely downy; margin reflexed, gills white, distant, arcuate; stem short, solid, pubescent; milk white, acrid, somewhat scanty. In woods. Whole plant white.