—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 preëminently a heat-forming 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 or 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 mushrooms.
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.