Pistachio. The nut of the pistachio (Pistachia vera) is used very largely for flavoring purposes and also for food. The tree is a native of Syria but has been cultivated in southern Europe for many years. The nut produced in America, though somewhat larger than the native Syrian fruit, has not half so high a palatable value. The pistachio is grown to some extent in the southern part of the United States and also in California. The kernel of the fruit is green in color and has a flavor which in some respects is reminiscent of almonds. It is used chiefly in this country in the manufacture of confectionery and ice creams.

Walnuts (Juglans nigra L.).—The American walnut grows wild over a very large portion of the country, especially the middle section west of Maryland to the Mississippi river. The walnut tree is especially abundant along the Ohio river, where it forms in the early summer a dense foliage. The trees often attain a very great size, reaching a diameter as great as five feet.

The walnut trees grow only on rich soil, hence, unless the country was very hilly and unsuitable for cultivation, the walnut forests were the first to fall before the axe of the pioneer. Later the demand for walnut lumber completed the devastation of the walnut forests, until now very often in the regions where fifty years ago the trees were extremely abundant a large walnut tree is rarely seen. The walnut lumber has peculiar lasting powers, and on account of its natural color and grain is of the highest value for building and ornamental purposes. The early farmers in the Ohio valley made their rail fences out of walnut trees. The wild nut grows in a dense kernel and is covered with a thick pericarp which is green even at the time when the fruit is ripe. After a frost when the fruit naturally falls from the trees the outer covering disintegrates. When the nuts are gathered by boys the outer covering is usually beaten off with clubs. It contains a coloring matter of a brown or brownish-black tint

GENERAL DISCUSSION.

427 which the early housewives used for dying homespun cloth. The bark of the tree also contains to a greater or less extent the same coloring matter. The kernel of the walnut, that is, the edible portion, is extremely rich in oil and protein and has a very pleasant taste. Like other nuts the walnut is best during its first winter, since on longer keeping the oil tends to become rancid and the fruit unpalatable.

White Walnut (Juglans regia L.).-The white walnut, commonly known as the English walnut, is grown very extensively in France. All the departments of south central and southeastern France grow these walnuts as a valued crop. The best walnut orchards are at an altitude of from 600 to 900 feet. Only the outer or exposed limbs produce perfect nuts. In planting the most important precaution is to give the trees plently of room, 15 yards is about the usual distance at which they are planted. The trees are cultivated and fertilized with manure and commercial fertilizers every two or three years. A bearing orchard of these white walnuts in France is worth from four to five hundred dollars per acre and may yield a revenue of from seventy-five to one hundred dollars a year per acre. The nuts ripen from the middle of September to the end of October. These nuts are used largely in America as a food, for which purpose the kernels are carefully extracted in halves, commonly known as "walnut halves." In France an excellent table oil is expressed from the dry nut which for many culinary purposes is valued as highly as olive oil. After extraction the oil cake is used for stock food. The white walnut is supposed to have been originally introduced from Persia, though it is commonly known as the English walnut. In the United States the butternut tree is commonly known as the white walnut.

The composition of the kernel of the dry walnut is shown by the following data:

General Discussion.-A brief description has been given above of the principal edible nuts used in the United States, accompanied by a statement of their chemical composition. The character of the food products is well

shown by the analytical data. Nuts as a whole are extremely oily substances and contain next in importance as a food material, protein. Alone they constitute an unbalanced ration in which the fat and protein are abundantly present at the expense of the starch and sugar. For this reason an exclusively nut diet cannot be recommended, as it surely tends to unbalance the ratio and to disturb the digestion in the great majority of cases. There are doubtless individuals of a peculiar temperament who can thrive on a diet of nuts alone, but such a case is exceptional. On the other hand the value of the nut as a food is undeniable, both as a nutrient and as a pleasant condimental addition to the food. The large percentage of oil in nuts also in many cases is beneficial from the well-known effect of oil in promoting the digestive activities, mechanical and otherwise. Nuts should be eaten in as fresh a state as possible, especially those of a highly oily character. Rancidity not only spoils the taste but interferes largely with their dietetic value. On account of the high amount of oil, nuts are preeminently a heatforming food and thus can be eaten very freely by those engaged in vigorous bodily exercise and during cold weather. They also form a food especially useful during periods of extreme exertion, since by their combustion they furnish abundant stores of heat and energy.

Many fads relating to foods flourish in various localities. Among them the school of dietetics, which advises a diet solely of nuts, is worthy of mention. It is true that life can be sustained for an indefinite time on a diet of nuts alone. If the nuts are sought in the forests and fields the good effects of the exercise and outdoor life are to be taken into consideration. There is no reason to believe, however, that the general condition of mankind, from a dietetic point of view, would be improved by an exclusive nut diet. The impossibility of supplying man with such a food product is also a factor in the discussion of the problem that should not be forgotten.

PART VIII.

FUNGI AS FOODS.

Mushrooms. Certain fungi growing wild cr in cultivated soils and having an expanded top on a hooded stem are known as mushrooms. The common form of mushroom (Agaricus campestris L.) grows wild over a large portion of the United States. It is especially abundant in the autumn, growing sometimes during the night after a warm rain, over large areas. When properly cooked it forms a delicious food and condimental substance, highly prized by connoisseurs and others. Belonging to the family of mushrooms, however, are many poisonous varieties which, when eaten inadvertently, often cause serious illness and sometimes death. For this reason mushrooms sold in the open market should be carefully inspected by experts authorized to see that the poisonous varieties are excluded. It not only requires a good botanist, but also one skilled in the practical differentiation of the different varieties by physical appearance rather than by botanical analysis, to properly separate the poisonous from the edible varieties.

Historical.-Mushrooms have been, since historical times, extensively used as human food. In a book written five centuries before the Christian era, Athenée, in his "Banquet of Learned Men," speaks of the poisoning of a mother and her three children by mushrooms. Hippocrates speaks of a girl who had been poisoned by mushrooms and who was cured by the administration of hot honey and by a hot bath. Theophrastes and Nicandre also speak of mushrooms and the poisoning that occurs therefrom. Both Cicero and Horace make reference to mushrooms. Horace advises that Epicureans should confine themselves to the mushrooms that grow upon meadows and refuse to eat all others on account of the danger from poisoning. Ovid also makes frequent allusions to mushrooms and speaks of the influence of warm rains upon their growth. Tacitus refers to the use of mushrooms for food, and Suétonius, in his "History of the Twelve Cæsars," relates that the Emperor Claudius was poisoned by a dish of mushrooms. It is, therefore, evident that from the earliest times mushrooms were extensively used and the poisonous properties of some of the varieties understood.

Production of Mushrooms.-As has already been mentioned, mushrooms grow wild over a large area of the United States. They are also cultivated very extensively, though not so extensively here as in European countries.

The best place for growing cultivated mushrooms is one where the light is excluded or diffused and where the temperature remains reasonably constant. Cellars, caves, and the artificial caverns made by quarrying are peculiarly well suited for the growth of different varieties of fungi, such as mush

rooms.

The art of growing mushrooms is not easily acquired. The directions given by the best authorities may be rigidly followed and failure ensue. The skill of the grower appears to be born, not made, and those who have acquired the art succeed where theoretical knowledge fails. For cultural purposes, the Agaricus campestris is most universally employed.

Soil. The soil best suited for the growth of mushrooms is one rich in decayed or decaying vegetable matter. Mushrooms are often found growing in localities where a log or stump has decayed or where the inorganic matter from the manure of cattle or horses has been distributed on the soil. Artificial beds for the growth of mushrooms are made up largely of organic manurial substances.

Spores.-Mushrooms are grown from spores. The mushroom produces a brown powdery material which consists of almost innumerable simple cells of ovate shape to which the term "spore" has been applied. A spore is not in the strict sense of the word a seed, but simply a cell which by proliferation produces the new fungus. Generally growers do not use these spores directly in seeding mushroom beds. Each complete spore, however, is, under favorable conditions, capable of proliferation or germination, producing a thread-like growth of a spider-web character which penetrates through the soil, prepared and manured, upon which a spore is germinated. This spiderweb-like growth, in the common language of mushroom growers, is called the spawn, more properly called the mycelium of the mushroom. When the conditions are favorable, there are formed on the threads of this mycelium small nodules, which are the earlier stages of the complete fungus itself. From the beginning of this growth until the final production of the mushroom two or three days or even a week may elapse. The earlier periods of this growth take place under ordinary circumstances, but the advent of a warm rain or other extremely favorable conditions causes the budding mushroom to grow at an enormously rapid rate. The mushroom may not be said to have a root, stem, and leaf, as is the case with an ordinary green plant, but is practically a single organism, assuming different shapes which are represented by the different varieties and species of growth.

Differing Varieties of Edible Mushrooms.-There is a very large variety of edible mushrooms differing in form, size, and shape from the Agaricus` campestris. In the Washington markets there are four principal kinds of mushrooms which are found growing wild in the vicinity of the city. These comprise the common mushroom-Agaricus campestris, the horse mushroom