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and Claret potatoes. The Bermuda potatɔ was the only one that had a white flower, the flowers of all the other kinds being purple. This was the only variety that had a white skin, and was white fleshed. It was round in shape, more tender, and more delicate to raise than the others, and did not keep so well.'

George Don, in 1831, enumerates several English early varieties, and says that “none of the above sorts, when true, produce blossoms.”' ?

At Wyoming Experiment Station,' in 1895, out of 56 varieties grown 14 did not bloom, but in 1896 but 4 varieties failed to bloom out of 56, and only one variety, Blue Victor, failed to bloom in one of the two years. In other parts of the State all the varieties grown came into bloom. In New York, during 1904, the variety Blue Victor was profuse in its bloom, and bore abundance of seed-balls.' Out of 300 varieties I have followed closely, having grown many for several years, I find that it is seldom that a variety will not bloom at some time in its life, and I am sure that many of the heaviest-yielding varieties bloom as freely as those of inferior merit. At Wyoming Experiment Station the ten heaviest yielding varieties all came into bloom both in 1895 and in 1896, in experiments conducted in various parts of the State.

The fruit, or seed-ball, is a globular or short oval berry, either green or green tinged with violet, brown, purplish, or yellowish in color, and from three-quarters to one and a half inches in diameter. It contains

1 “Nat. His. of Carolina," by Mark Catesby, F.R.S., 2d ed. 2 Don's “Gardener's Dictionary,'' 1831-8, Vol. IV., pp. 400-406. • Wyo. Bul. 32, pp. 54-63.

small white kidney-shaped seeds embedded in the midst of a green and very acrid pulp (Fig. 3). These seeds are sown for the purpose of raising new varieties.

The main vertical underground stem varies in length with the depth of planting. This stem branches at intervals, and each branch enlarges at the end to form a tuber (Fig. 12). Usually from two to four roots start

from the vertical underground stem at the base of each tuberbearing branch, but roots may start where such branches are absent. This characteristic growth may be seen by growing a potato in a barrel half full of soil and manure, and watering it well; then, as the stem grows, place soil round it, thus increasing the length of the underground portion and the number of tuber-bearing branches. The tubers may be

formed above ground, and FIG. 4-KIDNEY-SHAPED

POTATO (Does Pride) whenever they are abundant Showing the alignment of in the axils of the leaves there the eyes, and that the terminai buds tend to start are few or none below ground. first. Note the short, thick,

The tuber is an underground desirable shoots.

stem, and the eyes on it are equivalent to the leaf buds on a stem of a young peach or ailanthus. They are arranged inore or less spirally in both cases (Fig. 4). From the eye a number of buds may start; hence, in the case of new and expensive varieties, the tubers may be split through the

[graphic]

eyes, if desired, and a shoot obtained from each half. As each shoot sets a root it may be broken off and transplanted, and another may start. By these means and great care a pound of seed tubers has been made to yield 2,558 pounds of potatoes in one season.

Historical Note.-The early history of the potato is obscure. The most authentic information I have secured is that Sir Robert South well, the President of the Royal Society of England, at the meeting held December 13, 1693, stated that the potato was brought into Ireland by his grandfather, who obtained tubers from Sir Walter Raleigh, after the return of his expedition from Virginia. This was in the year 1584. It is now believed that Sir Walter Raleigh fitted out this expedition, but did not lead it personally, and never was in Virginia.

Timbs' “Curiosities of History,” page 233, places the date of its introduction to the British Isles as 1586.

CHAPTER II

SOME CONDITIONS INFLUENCING GROWTH

AND DEVELOPMENT

It is common knowledge that a certain amount of heat and an adequate supply of air and moisture are essential for plant growth. All plants that have green leaves require light, in addition, to enable them to assimilate carbon dioxid from the air, dissociate it into its component parts, and elaborate the carbon into such complex substances as starch, sugar, and other carbohydrates.

Influence of Light on Yield.-E. Pagnoul' placed colored glass over different potato plants. Two plants under darkened glass elaborated 31 and 20 grams of starch respectively, while those under ordinary glass elaborated 170 and 110 grams; at the same time plants under normal conditions elaborated 223 and 361 grams. To the favorable influence of abundant light this writer attributes the large yield of potatoes in a season when the aggregate number of hours of sunshine is unusually large. At Wisconsin Experiment Station coldness and cloudiness were believed to be the causes of a poor yield.

The Amount of Moisture.—The amount of water the plant can obtain from the soil is closely correlated with the mode of development. If the soil is very dry, and particularly if the tuber is cut, the seed tuber may be so weakened by loss of moisture that it cannot grow. If a tuber has access to but a small amount of water, there will be little or no root development, with little formation of leaf shoots, but tubers will be formed. Advantage is taken of this fact when small early potatoes are required, the tubers being placed in sand, in a cellar, when small tubers will form, but none or few leaves. Under certain conditions, with an abundance or excess of moisture, numerous leaf shoots and roots appear, but no tubers. An increase in the supply of moisture in the air has been found to favor the development of leaves on the shoots, where only scales were formed in an insufficient supply of moisture.

1 E. S. R., V., p.116.

? Wis. Report, 1902, p. 188.

Respiration.—We may say that all plants breathe or take in oxygen and give off carbon dioxid. With potatoes this is a necessary function, and if checked, growth is injured. It is probable that light induces some conditions more favorable to increased respiration than darkness; hence, if the object is to store potatoes, it will be better to hold respiration at its lowest point and keep them in the dark. Respiration cannot go on without force or energy, and as this must be supplied, at least partly, from the tuber, it follows that active respiration will be attended by loss of weight, and this goes on very rapidly when the tuber sprouts.

If we wish to “sprout” tubers, the best conditions for doing so are still undetermined.

Influence of Temperature on Respiration.All plants have a range of temperature at which respi

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