In any case we do not get farther back than about 1730 for potato-planting in Scotland, whereas in England, by 1684 the recommendations of the Royal Society had been largely adopted, especially in Lancashire, where the first serious beginning seems to have been made. On the other hand, the cultivation has not extended so rapidly in England as in either Ireland or Scotland.
The annual crop of Ireland is estimated as, on the average, equal to about one thousand three hundred and twenty pounds per inhabitant; that of Scotland, about three hundred and ninety pounds; and that of England, about one hundred and twenty pounds. Germany is the next largest producer to Ireland, and also the next largest consumer—the crops being equal to about one thousand and sixty pounds per head. Holland and Belgium each produce about five hundred and eighty pounds, and France about five hundred and fifty pounds, of potatoes per inhabitant per annum.
It is curious that, although Spain and Italy were the first cultivators and users in Europe, the product of each of these countries is now only about fifty-five pounds per head.
The annual value of the entire potato crop of Europe may be stated at about one hundred and sixty million pounds; and that of the United Kingdom at about one-tenth of this total. That of North America is about twenty million pounds more; and it is a curious instance of the vagaries of time that the Solarium tuberosum is now known in America as the 'Irish potato,' to distinguish it from the batatas, or sweet potato.
All this immense development of cultivation does not complete the topographical record of our tuber. It has been introduced into India, and is now successfully cultivated both in Bengal and in the Madras Presidency. It has found a home in the Dutch East Indies and in China; and its tastes and habits are affectionately studied in Australia. But as in the tropics it has to be grown at an altitude of three thousand feet, or more, above sea-level, it can never become so common in hot countries as in Europe.
It is not only as a food-plant that the potato has secured the respect and affection of mankind. Starch is made from it both for the laundry and for the manufacture of farina, dextrin, etc. The dried pulp from which the starch has been extracted is used for making boxes. From the stem and leaves an extract is made of a narcotic, used to allay pain in coughs and other ailments. In a raw state the potato is used as a cooling application for burns and sores. A spirit is distilled from the tuber, which in Norway is called 'brandy,' and in other places is used for mixing with malt and vine liquors. Many of the farinaceous preparations now so popular in the nursery and sick-room are made largely of potato-starch; and in some places cakes and puddings are made from potato-flour.
To the potato are also ascribed properties of another kind. The folklore of the plant is meagre, considering its wide distribution, but there are a number of curious superstitions connected with it. In some parts there is a belief that it thrives best if planted on Maundy Thursday; in others, that if planted under certain stars it will become watery. In Devonshire the people believe that the potato is a certain cure for the toothache—not taken internally, but carried about in the pocket. It is by several writers mentioned as a reputed cure for rheumatism in the same way; only it is prescribed that, in order to be an effective cure in such cases, the potato should be stolen. Mr. Andrew Lang mentions an instance of faith in the practice of this cure, which he came across in a London drawing-room. He regards this belief as a survival of the old superstitions about mandrake, and as analogous to the habit of African tribes who wear roots round the neck as protection against wild animals.
The value of the potato as food has been much discussed; but it seems to rank next to the plantain, and a long way behind either rice or wheat. The author of the Chemistry of Common Life has pointed to the remarkable physiological likeness of tribes of people who live chiefly on rice, plantain, and potato. The Hindu, the negro, and the Irishman are all remarkable for being round-bellied, and this peculiarity is ascribed to the necessity of consuming a large bulk of food in order to obtain the requisite nourishment.
It is not, of course, the root of the plant which we consume. The tubers known to the table are the swollen portions of the underground branches, and the so-called 'eyes' are really leaf-buds. It is by cuttings from these tubers, however, that the plant is mostly propagated. About three-fourths of the weight of the potato is water, and this may explain the injurious effect which excessive rainfall has on the crops. The disease which attacks the plant, and has been the cause of Irish famines, past and prospective, is a species of fungus, which first attacks and discolours the straws, and then spreads downwards to the tubers, increasing the quantity of water in them, reducing the quantity of starch, and converting the albumen into casein.
When this disease once appears it is apt to spread over wide areas where the same climatic influences prevail, and when the disease appears in any strength the crops are rapidly rendered unfit for human food. The trouble of the Irish peasantry of the West is that they have no alternative crop to fall back on when the potato fails. Their plots are too small for cereals, and they cannot be persuaded to cultivate cabbages and other vegetables along with their tubers. It is thus that, when the day of tribulation comes, the potato appears to be really a curse rather than a blessing to agricultural Ireland.