594 POTATO is not known ; the object evidently is to secure a method of propagation independently of the seed. Starch and other matters are stored up in the tubers, as in the perisperm of a seed, and in due season are rendered avail able for the nutrition of the young shoots when they begin to grow. The young shoots, in fact, derive their nourishment from the parent tuber until by the produc tion of roots and leaves they are enabled to shift for themselves. When grown under natural circumstances (without being earthed up, as is usually done by the cultivator) the tubers are relatively small and close to the surface of the soil, or even lie upon it. In the latter case they become green and have an acrid taste, which would probably render them objectionable to predatory animals or insects, and which certainly renders them unpalatable to human beings, and, in consideration of the known poisonous qualities of many Solanacese, might probably cause them to be unwholesome. Hence the recommenda tion to keep the tubers in cellars or pits, not exposed to the light, for the green colouring matter is, in this case, developed in the tubers independently of the direct action of light on the leaves. Among the six hundred species of Solanum less than a dozen have this property of forming tubers, but similar growths are formed at the ends of the shoots of the common bramble, of the Convolvulus sepium, of the Helianthus tuberosus, the so-called Jerusalem arti choke, of Sayittaria, and other plants. Tubers are also sometimes formed on aerial branches, as in some Aroids, Begonias, <tc. The production of small green tubers on the haulm, in the axils of the leaves of the potato, is not very unfrequent, and affords an interesting proof of the true morphological nature of the underground shoots and tubers. The so-called fir-cone potatoes, which are elongated and provided with scales at more or less regular intervals, show also very clearly that the tuber is only a thickened branch with " eyes " set in regular order, as in an ordinary shoot. The potato tuber consists mainly of a mass of cells filled with starch and encircled by a thin corky rind. A few vessels and woody fibres traverse the tubers. The chief value of the potato as an article of diet consists in the starch it contains, and to a less extent in the potash and other salts. The quantity of nitrogen in its composition is small, and hence it should not be relied on to constitute the staple article of diet, unless in admixture with milk or some other substance containing nitrogen. Letheby gives the following as the average composition of the potato Nitrogenous matters 2 1 Starch, &c 18 8 Sugar 3 2 Fat... .. 0-2 Saline matter - 7 Water . ...75 100-0 a result which approximates closely to the average of nineteen analyses cited in How Crops Grow from Grouven. In some analyses, however, the starch is put as low as 13*30, and the nitrogenous matter as 92 (Deherain, Cours de Chimie Agricole, p. 159). Boussingault gives 25 2 per cent, of starch and 3 per cent, of nitrogenous matter. Warington states that the proportion of nitro genous to non-nitrogenous matter in the digestible part of potatoes is as 1 to 10 6. The composition of the tubers evidently varies according to season, soils, manur ing, the variety grown, <fcc., but the figures cited will give a sufficiently accurate idea of it. The " ash " contains on the average of thirty-one analyses as much as 59 8 per cent, of potash, and 19 1 per cent, of phosphoric acid, the other ingredients being in very minute proportion. Where, as in some parts of northern Germany, the potato is grown for the purpose of manufacturing spirit great attention is necessarily paid to the quantitative analysis of the starchy and saccharine matters, which are found to vary much in particular varieties, irrespective of the con ditions under which they are grown. The origin and history of the potato are better known than in the case of many long-cultivated plants. It is to the Spaniards that we owe this valuable esculent, " optimum benigni Numinis donum, dapes grata diviti, pauperi panis," as it has been called by an eminent botanist. The Spaniards met with it in the neighbourhood of Quito, where it was cultivated by the natives. In the Cronica de Peru of Pedro Ciea, published at Seville in 1553, as well as in other Spanish books of about the same date, the potato is mentioned under the name " battata " or "papa." Hieronymus Cardan, a monk, is supposed to have been the first to introduce it from Peru into Spain, from which country it passed into Italy and thence into Belgium. Carl Sprengel, cited by Professor Edward Morren in his biographical sketch entitled Charles dr VEsduse, sa Vie et ses CEuvres, and to which we are indebted for some of the historical details given below, states that the potato was introduced from Santa Fe into England by John Hawkins in 1563 (Garten Zeitung, 1805, p. 346). If this be so, it is a question whether the English and not the Spaniards are not entitled to the credit of the first introduction ; but, according to Sir Joseph Banks, the plant brought by Drake and Hawkins was not our potato but the SWEET POTATO (see below). In 1587 or 1588 De 1 Escluse, better known under the Latinized appellation of " Clusius," received the plant from Philippe de Sivry, lord of Waldheim and governor of Mons, who in his turn received it from some member of the suite of the papal legate. At the discovery of America, we are told by Humboldt, the plant was cultivated in all the temperate parts of the continent from Chili to New Granada, but not in Mexico. Nearly a hundred years afterwards, in 1585 or 1586, potato tubers were brought from North Carolina and Virginia to Ireland on the return of the colonists sent out by Sir Walter Raleigh, and were first cultivated on Sir Walter s estate near Cork. The tubers introduced under the auspices of Raleigh were thus imported a few years later than those mentioned by Clusius in 1588, which must have been in cultivation in Italy and Spain for some years prior to that time. Be this as it may, the earliest representation of the plant i.s to be found in Gerard s Herbal, published in 1597. The plant is mentioned under the name Papus orbicidatus in the first edition of the Catalogus of the same author, published in 1596, and again in the second edition, which was dedicated to Sir Walter Raleigh (1599). It is, how ever, in the Herbal that we find the first description of the potato, accompanied by a woodcut sufficiently correct to leave no doubt whatever as to the identity of the plant. In this work (p. 781) it is called " Battata Virginiana sive Virginianorum, et Pappus, Potatoes of Virginia." Gerard says "The roote is thicke, fat and tuberous ; not much differing either in shape, colour or taste from the common Potatoes, saving that the rootes hereof are not so great nor long ; some of them as round as a ball, some ouall or egge-fashion, some longer and others shorter ; which knobbie rootes are fastened unto the stalks with an infinite number of threddie strings. ... It groweth naturally in America where it was first discovered, as reporteth C. Clusius, since which time I have received rootes hereof from Virginia otherwise called Norembega which growe and prosper in my garden, as in their owne native countrie. " The "common Potatoes" of which Gerard speaks are the tubers of Convolvulus batatas, the Sweet Potato, which nowadays would not in Great Britain be spoken of as common. Evidently the author attached great importance to the potato, for in the frontispiece to his volume he is represented with the flower and foliage of the plant in
his hand. In his opinion it was, like the common potato,