The Tuberaceæ are subterranean fungi. The common truffle so much prized by epicures is a good representative. It is found a foot or more under the surface of the earth, and of such value is it that in some countries pigs are trained to hunt it from its hiding place. It is one of the few foreign growths apparently not taking kindly to our country. Efforts have been made to import and cultivate it, but without success. It is possible, even probable, that it may yet be found in America by assiduous search. I have said that there is but one way to distinguish the edible from the non-edible fungi; that is by mastering the characteristics of each species one by one. There are signs which point to the evil and those which point to the good, but they must be used as signals, not directors. A nauseous, fetid odor should condemn a species as non-edible at once. Those having the flavor of flour or fresh meal are generally accepted as worthy of trial. Slimy, water-soaked, partially decomposed plants, or those impressing one as unpleasant in any way, should never find their place upon the table. Do not eat of any toadstool, unknown to the collector, beyond the careful and systematic testing required to determine whether it is edible or not. A few species have a serious charge remaining against them; that of partiality. They unmistakably signify with whom they will agree and with whom they will not. These are notably Clitocybe illudens, Lepiota Morgani, Panæolus papilionaceus, all specialized in their places in the text. Other species have hereditary taints upon their reputations. Most, if not all of them have stood present tests and relieved themselves of suspicion. But, alas that it should be so! The stigma must rest upon them for yet a while and until their defenders are so numerous that their purity, without a smirch, is popularly proclaimed. Wherever wood grows and decays as it will, Polyporus, Panus, Lenzites, Schizophyllum and kindred genera stand prominently forth in countless numbers. The great majority of them are inedible because of their woody substance. A few are valued as food. Very many of them yield their soluble matter and flavor when boiled, and in this way make excellent soups and gravies, just as flax-seed and the bark of the slippery elm yield succulent matter. These, however, are not, with a few exceptions, mentioned in this book. Numbers of Clavarieæ and Hydneæ are in the same category. M.C. Cooke tersely says: “Fruits that are not peaches or apricots may be very good plums.” In the introductions to genera their attributes are given; under “Instructions to Students” every guide to identification and selection will be found.