Page:The American Cyclopædia (1879) Volume XIII.djvu/789

 POTATO 765 . 2.-Branch b deyelopcd upon it. That this is the real nature of the tuber is shown by the fact that under favor- able circumstances the branches above ground will take on a similar development. As it has been cultivated for generations with a view solely to the im- provement of the tu- bers in size and num- ber, the other parts of the plant have dimin- ished ; in the natural statethe portion of the plant above ground is large and vigorous, while the tubers are small and few; in cultivation the tuber has been developed to such an extent that the stems are com- paratively weak, and many varieties do not flower and produce seeds. The vine, as it is popularly called in this country (in England the haulm), in the different cultivated kinds, pre- sents considerable variety in size and vigor, while the leaves differ in the amount of sub- division and also in their color. The flowers in some varieties are twice as large as in oth- ers, and vary from white and bluish white to a handsome light purple; the berry, or seed ball, usually about an inch in diameter, is yel- low or purplish. In common with many other solanums, the herbage and fruit of the potato contain the alkaloid solanine, an exceedingly active poisonous principle, four grains of which will kill a dog ; an extract prepared by evap- orating the juice of the herb has been used in medicine as a narcotic in doses of one eighth to one half grain. The foliage of the potato may be regarded as poisonous, but the danger- ous principle does not exist in properly grown and carefully kept tubers; these are mainly starch, and this, wherever it occurs, or how- ever acrid and poisonous may be the plant producing it, is always wholesome. But sola- nine is developed in the sprouts which form upon the tubers, and in the skin of the tuber when exposed to the light; some varieties have a tendency to form potatoes so near the surface that they become exposed by the wash- ing away of the soil; such tubers are green where exposed, and are very acrid and unfit for food ; the same thing happens when pota- toes after digging are long exposed to light; any sense of acridity in the throat after eat- ing potatoes indicates that they have been im- properly kept, and should- be rejected. The potato may be multiplied in three ways: by division of the tuber, the ordinary method in cultivation; by cuttings of the stems, which take root readily in a proper propagating frame, a method sometimes resorted to for the rapid multiplication of a rare variety ; and by seed. The first two processes only subdivide the individual, while from the seed new varie- ties are obtained; several of the newer and 679 VOL. xiii. 49 most valuable varieties now in cultivation, but which differ greatly in size, form, color, and time of maturing, were from the seeds con- tained in a single seed ball, which had been saved by the merest accident. The seeds are sown in a hotbed in February or March, and when danger of frost is over the plants are transferred to the open ground. At the end of the season the tubers are of good size and have their qualities sufficiently manifested to show whether it is worth while to give them further trial. Within the past ten years more new varieties have been produced than in all previous years. In ordinary cultivation small potatoes are planted whole; those of mode- rate size are cut into two or three pieces, or good-sized tubers are cut into single eyes. The first named method is habitually followed only by careless farmers ; in case of scarcity of seed (as the tubers for planting are called) small refuse potatoes may be used without any per- ceptible change the first season, but the con- tinuous planting of small tubers year after year tends to diminish the size of the whole crop. If a whole large tuber be planted, a few of the shoots which start first will appropriate all the nutriment, and a large proportion of the eyes will remain dormant. The object is to give each bud or eye sufficient nutriment to sustain the growth of the shoot until it forms roots. Good- sized, well formed potatoes cut to single eyes are the best ; in cutting care is taken to give each eye as much of the tuber as possible. Where it is desired to make the most of a rare kind, the eyes are sometimes divided into two or three pieces ; as each eye usually has several buds, this division is practicable. The end of the potato nearest to the plant is called the stem end, and the opposite the seed end ; at the seed end the eyes are much more numerous than elsewhere, and, being more excitable than the others, start first. In the experiments of Dr. F. M. Hexamer of New Castle, N. Y., out of 100 potatoes planted whole, 98 started from the seed end. His ex- periments show that the potato, like other branches, has the power of producing adven- titious buds ; he peeled 70 potatoes so that no eyes were visible, and planted them in sepa- rate hills; half the number produced shoots and ripened a crop, and out of 80 hills plant- ed with pieces without eyes, but having their portion of skin, 13 grew, and in every case the sprout started from the cut surface. When a potato is placed in sufficient heat to excite growth, but under circumstances unfavorable to the development of leafy branches, a singu- lar transference of nutriment takes place ; the starch and other principles of the old tuber, which in favorable conditions would have been expended in producing shoots, here produce new tubers ; and it is not unusual to find late in spring, at the bottom of a barrel or bin where light has been completely excluded, specimens with small new potatoes attached to them. In this way gardeners sometimes