The edible ones are white-spored, have hollow stalks, and are seldom more than two inches across the pale yellow or drab cap. which is often concave on top and raised in the centre. One class of gill-bearing fungi exude, when broken, a milky juice. The species of this kind belong to the genus Lactarius. Some have a very acrid juice, but one (Lacterius dcliciosus) is consid ered tery choice by mushroom lovers. It grows in damp woods in mountainous regions, but is not common in lowlands. It cannot be mistaken for any injurious species, as the milk exuded by it is always red with a tinge of orange, and slowly changes color to greenish. The fungus is a little lighter in color than the milk exuded by it.
Boletus is one of the most common genera. The species are rather difficult of identification and should not be eaten by a novice. Some of the Gasteromyeetes, for example, the puffballs (Ly eoperdon, giganicum and Lycoperdoe cgathi [orate), are common edible species. The former attains a diameter of ten inches or more has a smooth, white, kid-like surface when young, with a firm white or pale yellow flesh. The other is six inches in diameter, flattened and tessellated on top. and contracted at the base. In color it varies from white to brown. The puffballs should be taken while young and before the spores are developed. One species (Sclerodcrina vulyere), related to the ones just described, and suspected of being injurious, may be recognized by its tough, hard, yellowish-brown, warty exterior, and purplish-black interior mottled with white. Among the most highly prized of all the edible fungi are the morels and truffles (Tuber meleno spornm).
Since several species of mushrooms have not yet been proved harmless and since occasional eases of poisoning are still attributed to their use as food, the following rules, formulated by Farlow, are given as guides for the inexperi enced collector: "Avoid fungi when in the button or unexpanded stage; also those in which the flesh has begun to decay even if only slightly. Avoid all fungi which have stalks
with a swollen base surrounded by a sae-like or scaly envelope, especially if the gills are white. Avoid fungi having a milky juice, unless the milk is reddish." These rules are not absolute, because there are exceptions to them. but are safe for the novice to follow. See FUNGI, EDI BLE AND POISONOUS.
Alusunooms AS Fool). Since mushrooms and other edible fungi are often said to be nutritious food, to contain large' quantities of protein, and to rank close to meat as sources of nitrogenous material, extravagant statements have been made concerning them. When fresh, mushrooms have the following percentage composition: Water, 88.1; protein, 3.5; fat, 0.4; nitrogen-free extract, 6.0; crude fibre, 0.3; and ash. 1.2. Other edible fungi closely resemble them so far as analyses have been reported. Like all green vegetables, mushrooms have a high water content in propor tion to their bulk, and as regards protein con tent, they rank about the same as potatoes, to which they are decidedly inferior in food value, since they contain much less carbohydrates, and the nitrogen present is largely in the form of non-albuminoids. which are thought to have little food value. The numerous studies which have been made show that mushrooms arc not thor °uglily digested. Recent experiments show that "5 to 59 per (put. is indigestible. See Plates of EDIBLE AND POISONOUS FUNGI.