a little more for digging. The variety controls the yield to a large extent, and there is much more likelihood of obtaining a 300-bushel crop from a variety capable of yielding 600 than from one whose maximum yield is 300 bushels. This fact is realized, and the high prices paid in recent years in Great Britain for seed potatoes of good quality, heavy yielding, and disease-resisting varieties are legitimate and proper recompense to the men who have the skill to breed such.

These new varieties are profitable to grow because there is an assurance that the crop will yield well, and that it will keep well; hence there is an opportunity to hold it until it can be sold at a profit. These farmers realize that the best is none too good, and that it is useless handling varieties that are out of date. The potato grower of Great Britain and Europe must be up to date if he is to stay in the business. High-priced seed receives more care in storage and is handled more intelligently, the seed-bed is better prepared, and the result is better farming. The farmer who grows such crops is a more thoughtful and better business man, as slovenly methods have to be abandoned.

Yield is influenced by the size and number of tubers at a root. Uniformity and good size are desired. Potatoes vary in size from almost nil to six pounds each or more. In Doe's Pride one plant set 21 tubers, varying in size between 1-10 ounce and 61⁄2 ounces ; in other words, one potato was 65 times larger than the other. In the East potatoes over 8 ounces in weight are large. Medium-sized tubers of merchantable value vary between four and eight ounces.

Sec

onds between two and four ounces, and tubers iess than this weight, are hardly worth picking up.

3. Ability to resist diseases. No varieties can be termed "disease proof," but many varieties are better disease-resisters than others. Stuart, of New Hampshire, found that the variety Hulett's Rust Proof was the only one that was disease-resistant out of several varieties, although the varieties Dakota Red, Green Mountain, New Queen, and Enormous showed some resistance. Hulett's Rust Proof falls below the requirements in other respects and is of little value, and in Minnesota has been found to be subject to disease. At Ontario Agricultural College, Carman No. 3 and Stray Beauty resisted disease well. At Minnesota Experiment Station, Rural New Yorker and Sir Walter Raleigh showed some resistance.2

4. The color of the skin and tuber. Many of the colored-skinned varieties of potatoes, and those showing a blush of pink—as, the Beauty of Hebron, Early Rose, etc.-belong to a type which have white blooms. They are generally early maturing, rather liable to disease, and of good quality, according to the American standard. The colored-skinned early varieties are generally more readily sold than the late ones, although in some districts colored-skinned potatoes are not objected to on the market. All colored-skinned potatoes

are not deficient in vigor. Some are among the best disease-resisting and best-flavored varieties, but the red color of some weak varieties has rendered some growers skeptical of all.

1 Minn. Bul. 87, p. 2.

Minn. Bul. 87, p. 10.

5. The nature of the skin. The skin may be thick, medium, or thin. Some growers claim that thickskinned varieties are of better quality than thin-skinned ones, but such correlation does not always exist. Potatoes grown on sandy soils usually have smoother skins than those grown on heavy loams. Some varieties develop a netted, or rough, skin as they mature in storage, although such may not be apparent at harvest-time. The rough, or netted, skin in these cases appears to denote maturity, and this may account for the common idea that a rough-skinned potato is of good quality. The size and type of netting (Fig. 20) varies with the variety, and the conditions under which it is grown. 6. The shape. Most of the recent introductions, exclusive of the Early Rose type, have had a tendency to partake of the flat-round or oval (Fig. 21). These shapes have been sought because such potatoes appear to be of better quality consistent with an economical shape and shallow eyes. The probable explanation is that in a flat-round or thinnish potato there is a greater surface in proportion to the bulk. The greater the surface the larger the percentage of the tuber taken up in the cortical layer and outer medullary layer (Fig. 18). These are the starch-bearing areas, and as they are increased the inner medullary layer, or pith, which has little starch, is diminished, thus rendering the potato more uniform. Whatever shape is desired can be be obtained, but a potato should be true to shape. The tendency of a tuber to become pointed or drawn out at the tip or butt end, especially if the variety is a flat-round or round, indicates lack of vigor (Fig. 21).

7. Depth and frequency of eyes. Deep eyes (Fig. 21), to some extent, are regarded as associated with robust

FIG. 21-THREE FAVORITE SHAPES OF POTATOES (Upper row, the broad surface; lower row, the narrow surface.) Beginning on the right, the small one is a flat-round; the center one, kidney; the largest one, on the left, elongated oval. Notice the shallow, wide eyes on the latter; they are the most desirable. The eyes of the flat-round

are too deep.

ness and, frequently, coarseness. They are wasteful in peeling. Deep eyes tend to hold moisture, which hastens decay when the potatoes are stored.

8. Time of maturity. In the Northern States pota