The question often asked is: By what rule do you distinguish between edible and poisonous mushrooms? The answer usually surprises the questioner--there is no general rule. All such rules which have been given are false and unreliable. The quality of each was learned, one at a time. Sweet and sour apples alike grow on large and small trees, may be red or green, large or small, oblong or globular, and no visible appearance gives the least clue to the quality. In a few genera certain rules may be applied, as in Clavaria--all not bitter or tough are edible. But such generalizations are each limited to its own genus. The toadstools containing deadly poisons are thought to be confined to one genus of the gilled kind--Amanita, and to Helvella esculenta, now Gyromitra esculenta, to which are charged fatal results. The poisonous qualities of Gyromitra esculenta are not proven. Recent testings of this species prove it to be harmless and of good quality. By far the greater number of species contained in Amanita are notable for their tender substance and delicious flavor. By their stately beauty and unusual attractiveness both the poisonous and harmless kinds are seductive. Any toadstool with white or lemon-yellow gills, casting white spores when laid--gills downward--upon a sheet of paper, having remnants of a fugitive skin in the shape of scabs or warts upon the upper surface of its cap, with a veil or ring, or remnants or stains of one, having at the base of its stem--in the ground--a loose, skin-like sheath surrounding it, or remnants of one, should never be eaten until the collector is thoroughly conversant with the technicalities of every such species, or has been taught by one whose authority is well known, that it is a harmless species. This rule purposely includes the renowned Amanita Caesaria, everywhere written as luscious. I regard it as the most dangerous of toadstools, because of its close resemblance to its sister plant--the Amanita muscaria--which is deadly. In the description of these species, other forcible reasons are given. Another deadly species--the Amanita phalloides--is frequently mistaken by the inexperienced for the common mushroom. Safety lies in the strict observance of two rules: Never eat a toadstool found in the woods or shady places, believing it to be the common mushroom. Never eat a white- or yellow-gilled toadstool in the same belief. The common mushroom does not grow in the woods, and its gills are at first pink, then purplish-brown or black. If through carelessness, or by accident, a poisonous Amanita has been eaten, and sickness results, take an emetic at once, and send for a physician with instructions to bring hypodermic syringe and atropine sulphate. The dose is 1/180 of a grain, and doses should be continued heroically until the 1/20 of a grain is administered, or until, in the physician's opinion, a proper quantity has been injected. Where the victim is critically ill the 1/20 of a grain may be administered. In every case of toadstool poisoning, the physician must be guided by the symptoms exhibited. Professor W.S. Carter, by numerous exhaustive trials upon animals, has proved that atropine, while valuable as against the first, is not an antidote for the late effects of the greater toadstool poisons. (See his chapter on toadstool poisons, especially prepared for this work.) There are other species which contain minor poisons producing very undesirable effects. These are soon remedied by taking an emetic, then one or two doses of whisky and sweet oil; or vinegar may be substituted for the whisky. A few species of fungi are innocuous to the majority of persons and harmful to a few. So it is with many common foods--strawberries, apples, tomatoes, celery, even potatoes. The beginner at toadstool eating usually expects commendation for bravery, and fearfully watches for hours the coming of something dreadful. Indigestion from any other cause is always laid to the traditionary enemy, fright ensues, a physician is called, the scare spreads, and a pestilential story of "Severe Poisoning by Toadstools," gets into the newspapers. The writer has traced many such publications to imprudences in eating, with which toadstools had nothing to do. The authoritative analysis of several common food species by Lafayette B. Mendel, of Sheffield Laboratory of Physiological Chemistry, Yale University, is given, and will correct the popular error about the great nutritive value of fungi, arising from previous erroneous analyses. While species are reported as found in certain localities, it by no means follows that their growth is confined to these places. A species reported as found in the Adirondack mountains, unless belonging to the few peculiar to northern regions and high altitudes, is reasonably sure to be more plentiful in a like habitat south and west of them. South it will appear earlier and its season last longer. Size is largely dependent upon latitude and may vary greatly in the same group. Temperature, moisture, favorable nourishment are important factors in growth. Each species has its favorite habitat, and will thrive best upon it. There are few things under the sun upon which fungi do not grow. Their mission is particularly directed toward converting decaying matter, or matter which has accomplished its work in one direction, into usefulness in another. They are the wood-choppers, stewards, caterers of the forest, converters in the fields and chemists everywhere. They can not assimilate inorganic matter because of the absence of chlorophyl in their composition, but in organic matter they are omnivorous. When they feed on dead substances they are called saprophytes; when their support is derived from living tissues, parasites. Scores of species of fungi were found in the forests, ravines and clearings of the West Virginia mountains from 1881 to 1885 inclusive, and eaten by the writer years before he had the opportunity to learn their names from books or obtain the friendly assistance of experts in identifying them. He knew the individuals without knowing their names, as one knows the bird song and plumage before formal introduction to the pretty creatures that charm him. After he was able to get European publications upon the subject, and by their aid trace the species he had eaten to their names, descriptions and qualities, he was surprised to read that many of them were warned against as deadly. As informed by these books, he properly ought to have died several times. It soon became evident that authors had followed one another in condemning species, some because they bore brilliant hues, others because they were unpleasant when raw (just as is a potato), rather than investigate their qualities by testing them. Here was a realm of food-giving plants almost entirely unexplored. The writer determined to explore it. Instead of the one hundred and eleven species then recorded by the late Doctor Curtis as edible, my number of edible species now exceeds his by over six hundred.