DIVISION OF MICROSCOPY.

The exhibit of the Microscopist, Dr. Thomas Taylor, consists of about 500 water-color drawings, a large proportion of which represents the leading types of the genera of microscopic fungi; another section of the exhibit presents the results of original investigations upon chemical tests for flax, cotton, ramie, silk, wool, hair, and both animal and vegetable cellulose; and still another series, illustrating the principal vegetable starches to the number of about 100 varieties. These drawings present highly magnified views of all these microscopic objects, including those most important in economic mycology, especially the fungi commonly known as molds, so destructive to vegetation. The edible and poisonous mushrooms are distinguished in one class of these drawings.

The importance of the mushroom as an article of diet has never been properly understood in the United States, nor is it generally known how abundant our supply of edible mushrooms is. Many of those popularly supposed to be poisonous are not merely innocuous but highly nutritious, containing, as they do, many of the elements of animal food.

In France, Germany, and Italy the mushroom forms so important a part of the food of the people that one distinguished writer has spoken of it as the "manna of the poor." In Transylvania the oyster mushroom is so abundant, and is so largely used, that tons of it may often be seen in the markets; and in some parts of Germany the Morel mushroom is so popular that the people, finding it to grow best on a soil treated with wood ashes, were accustomed to burn down portions of the forests in order to secure favorable spots for its cultivation-a practice which the Government ultimately found it necessary to interdict. It is hoped that the collection of drawings, which has been made with so much care by Mr. Taylor, will serve to call public attention to the value of the mushroom as an article of food, and at the same time furnish means of discriminating between the poisonous and the edible varieties of the plant. Particular pains have been taken to represent the last-named class of plants as fully as possible, a number of collectors having been employed for the purpose in various parts of the United States. Among these may be mentioned Professor Peck, of New York, who, in that State alone, gathered specimens of no less than 80 species of mushrooms, including several which are new to science. The specimens furnished by Professor Peck are admirably copied and colored to nature; and there

are also a number of excellent photographs, made from specimens furnished by various collectors, representing different genera and species of the same class of plants.

Another series of drawings illustrates the action of pear-tree blight, showing the effects of the chemical changes which take place in the interior structure of the tree under the attacks of the fungus to which this disease is due. The disease of plum and cherry trees, known as "black-knot," is illustrated in a similar manner, some of the drawings exhibiting it as it appears to the naked eye, while others show in detail its distorted, woody structure. The fungus which produces it is also shown at various stages of its growth.

The fungus Peronospora infestans, which causes potato-rot, is illustrated in the various stages of its growth. There is also a series of drawings of its "resting-spores," recently discovered by Professor Worthington Smith, and so named from the fact that they remain for months in a stationary condition, or, in other words, rest for that time without germinating.

There is an interesting series of drawings representing, as seen through the microscope, the mold of bread, cheese, jellies, &c., and illustrating their habits of growth, a knowledge of which may often be useful in preventing beer or milk from souring, and wine or bread from becoming "ropy."

One of the most curious of the cryptogamic plants is the Protococcus nivalis, which we believe was first found by Captain Parry during his northern exploration, and to which was given the name of "red snow,” from the fact that it gives its own red color to the surface of the snow on which it grows. This singular little plant is represented by several drawings of exquisite finish and color.

The fibers of hemp, flax, jute, ramie, esparto grass, and Australian flax, as well as wool, silk, calf's hair, and the hair of the Cashmere and Angora goats, are exhibited as seen through the microscope, both in their natural condition and under various forms of chemical action. In the course of his investigations on this subject, Dr. Taylor has discovered a number of new chemical tests by which the presence or absence of certain of these fibers, in every fabric, may be determined. This series of drawings will, therefore, be of considerable interest to manufacturers of textile fabrics, to dealers in that class of goods, and to the Government, which, besides being an extensive purchaser of clothing for the Army and Navy, is largely interested in determining correctly the materials composing the fabrics which pass through the customhouses.

The investigations to which these drawings relate are still in progress; but the great majority of the drawings relate to the leading families, orders, and genera of cryptogamic plants or fungi, of which by far the greater number are microscopic in size. The latter are often visible to the naked eye when massed together in large numbers, presenting in some

cases the appearance of a pigment on the surfaces of the plants upon which they fasten. In such cases the microscope sometimes reveals millions of spores to the square inch. The ravages of these minute vegetable organisms are incredible in their extent. The potato has, at times, been threatened almost with extinction. Grasses have been affected by them, and the cereals throughout large districts have at times suffered blights so serious and often repeated that the farmer has been almost ready to abandon their cultivation in despair. Fields of hops, vineyards and orchards have withered under their blighting touch, and in lower latitudes they have assailed coffee plantations, and groves of orange, lemon, and olive trees, with equally fatal results. Even the lordly forest trees have not in all cases escaped their devastating influence, and at the present moment many of the stately maples in the public grounds of our cities are withering under the insidious attacks of these minute destroyers. In short, there is hardly any department of agriculture, horticulture, or forestry that can claim exemption from their ravages; and the importance of a correct knowledge of their characteristics, modes of propagation and development, and the conditions under which they tend to flourish or decay, can hardly be overestimated. As a contribution toward the dissemination of such knowledge, the collection just described must be regarded as possessing a high practical value.

No large collection of well-executed drawings of cryptogamic plants has heretofore existed in this country; but by the assistance of Dr. M. C. Cooke, of London, and others, Dr. Taylor has supplied the defect in an admirable manner, and has formed a collection which will be of permanent value to mycological science. The drawings, nearly all of which were made from nature for the special purpose to which they are now destined, exhibit a high degree of delicacy and finish.

Mushrooms, in their composition, more nearly resemble flesh than any other vegetable. Dr. Marcet proves that, like animals, they absorb a large quantity of oxygen, and give out in return carbonic acid, hydrogen, or azotic gas. Chemical analysis demonstrates the presence in their structure of the several components of which animal matter is formed, many containing sugar, gum, resin, fungic acid, various salts, albumen, adipocere, and ozmazone, "which last is that principle that gives flavor to meat gravy," according to Dr. Badham.

Fungi are applicable to other than culinary uses, though their most important use is the gastronomic one. To obviate the difficulty arising from the prejudice against the wholesomeness of any mushroom, Mr. Berkeley recommends a good quantity of bread to be eaten with them. He is of opinion that mushrooms are only indigestible when eaten alone or in imprudent quantity. Of course this remark applies equally to any sort of mushroom, though it is made with reference to the one in familiar

use.

As an indirect but very important article of diet, the tiny fungus known as yeast stands pre-eminent. It is composed of globular cells

which produce other cells with incredible speed, and the interchange of fluids on either side of the membrane is the cause of the fermentation. German yeast is formed of the dried globules. The Polyporus betulinus makes very superior razor strops, its substance containing minute crystals; the Polyporus squamosus is also good for this purpose, if cut from the tree in autumn, then flattened in a press, rubbed carefully with pumice, cut into slices, and each slice fastened to a wooden stretcher. The Polyporus fomentarius forms the amadou of commerce, formerly used only as "German tinder," but now applied by, at any rate, one medical practitioner in sheets to protect the backs of bedridden patients. Gle. ditsch relates that the poorer inhabitants of Franconia stitch it together and make garments of it. Polyporus ignarius is used as snuff in the north of Asia; Polyporus officinalis was formerly used as medicine, but is so employed no longer; Polyporus sulphureus furnishes a useful dye. Coprinus atramentarius may be made into ink; Amanita muscarius furnishes poison for vermin, and is an ingredient in some intoxicating liquors. Wood impregnated with the metallic-green spawn of the Peziza is of great value in the delicate inlaid work known as Tunbridge ware. A small fungus belonging to the Ascomycetes class, and known as ergot of rye, furnishes a powerful and useful medicine, though in the hands of the ignorant it is an extremely dangerous poison.

Mr. Berkeley suggests that decayed fungus would form good manure. Such being the case, it would be well worth the trouble to let the laborers' children collect them, and throw them into a heap like dead leaves for leaf-mold. Thus even the poisonous species might be utilized.

But to enable us to turn fungi to the best profit, we must learn to discern the good from the evil, and for this we must cultivate patience and close observation. General rules will not suffice us. The test of a silver spoon will not insure safety. Odor is a good guide; those smelling offensively must be avoided; those with savory or aromatic perfume are generally innocuous; but this test cannot always be trusted, for there are some poisonous and deleterious species which have no smell at all. Color stands for nothing, for the snowy whiteness which in some is the garb of innocence, serves others, as Dr. Badham says, as the mask for guilt. We shall do well to regard all milky fungi with suspicion, and avoid bringing them into our culinary experiments; also, we had better eschew those with a biting or acrid smell or flavor.

We labor under a general impression that all fungi are poisonous except our common mushroom. This is very far from being the fact. Many species now despised form valuable articles of food, and the greater number of the rejected ones are innocuous, or only deleterious in a slight degree.

Mr. Taylor proposes to make a collection of all the known edible mushrooms of the United States, of which descriptions will, from time to time, appear in the Monthly Reports of the Department of Agriculture.

Types of the following families, orders, and genera are exhibited. Group A, from 1 to 39 inclusive, represents types of the orders and genera of the family Hymenomycetes.

Group B, from 40 to 56, represents types of the order, and genera of the family Gasteromytes.

Group C, from 57 to 119, represents types of the orders and genera of the family Coniomycetes.

Group D, from 120 to 171 inclusive, represents types of the orders and genera of the family Hyphomycetes.

Group E, from 172 to 184 inclusive, is miscellaneous, consisting mostly of types of fungi destructive to vegetation.

172. Ecidium cornutum, Pers.

173. Cranberry, long vine, New Jersey.

174. Cranberry, short vine, New Jersey.

175. Various varieties of New Jersey cranberries.

176. Uredo effusa.

177. Ecidium of the ash.

178. Black knot of the cherry, Sphæria morbosa.

179. American grape fungus, Peronospora vitis viticola (Berkley & Curtis). 180. Orange leaf, covered with black fungus matter.

181. Exhibits a microscopic view of the fungus on the orange and orange leaf. This fungus destroys the commercial value of the Florida oranges when they are affected by it.

182. Arctic red snow, a cryptogamic plant. (See Micrographic Dictionary.)

183, 184 represent abnormal growths on the foliage of the maple and other trees, formerly supposed to be a fungus, which was named Erineum, but they are now considered to be only abnormal growths.

Group F, 185, consists of a series of photographs representing the connective tissue of the mammary glands of a scirrhus cancer. The object of the examination was to detect mycelium or spores of fungoid matter, if present, in the tissue. Portions of the cancer cells were treated with dilute boiling caustic potash until a thin film of it floated on the surface of the liquid. The film was next floated on a microscopic slide, and photographs made from it direet. In these preliminary experiments no fungus matter was observed.

Group G, from 186 to 211 inclusive, represents the results of a series of experiments on textile fabrics, fibers, etc.

Group H, from 212 to 320 inclusive, represents types of the family Ascomycetes.

Group I, from 321 to 324 inclusive, Physomycetes, after Worthington Smith.

Group J, from 1 to 29 inclusive, edible mushrooms, after W. Smith. Group K, from 30 to 60 inclusive, poisonous mushrooms, after W. Smith.

28 CEN, PT 2