THE POTATO.

HISTORY AND HABITS.

The potato (Solanum tuberosum) is a native of the table-lands of the Andes of South America. Centuries ago it was found by travelers growing wild in Chili, at Cuzco in Peru, at Quito in Ecuador, and in the forests of Bogota in New Granada, 8,694 feet above the level of the sea. Potatoes have been cultivated at Quito from time immemorial, and are among the finest in the world. This city is situated on an extensive plain, at an elevation of 10,233 feet. The mean temperature of the climate throughout the year is about sixty degrees Fahrenheit, and varies from this but little at any particular season. The country has the appearance of perpetual spring. There are no sudden changes from heat to cold, no violent storms of rain and wind. The land is refreshed by distilling dews and gentle showers.

The soil of these table-lands, which are the uplifted beds of an ancient ocean, is generally composed of disintegrated rocks and shells, of the detritus of the monntains, and of vegetable mold, and belongs to the geological formation of the secondary or the tertiary period. It is, therefore, light, porous, and friable, and contains large proportions of sand,lime, and vegetable substances. It is also naturally well drained, though retentive of sufficient moisture, and, from its elevated and airy location, is cool and moderately dry.

Such is the native home of the potato, where it grows spontaneously, renewing itself from year to year from its tubers and seeds. It retains the verdure of its foliage unimpaired throughout the entire season, and when its tubers and seeds are fully matured, it dies, not of any injury from external influences, but because its period of life has terininated.

From this brief history of the habits of the potato, the following principles may be deduced: 1. That the location for its culture should be elevated and airy. 2. That the climate should be temperate, not subject to extremes of heat and cold, nor violent storms of wind and rain, having a mean temperature of about sixty degrees. 3. That the soil should be light, well drained, and composed of the proper proportions of sand, lime, and vegetable mold.

These principles lie at the foundation of the successful cultivation of the potato. If they are regarded, good crops may be expected; if they are neglected, the result will be poor crops, degeneracy, and disease of the plant. Although the potato is of tropical crigin, (tropical in its latitude though not in climate,) and has its favorite locality, in which it will grow with certainty and in perfection, yet such is its adaptability that it may be grown, by careful culture, with tolerable success, from Patagonia to Labrador, and from the Cape of Good Hope to Iceland.

DISEASES.

There are difficulties to be encountered in the cultivation of the potato, when removed from its native locality, which are unavoidable, and can be overcome only in part by a thorough knowledge of its origin and habits. The most formidable of those are the diseases of rust, curled

leaf, and rot. The first two are only the incipient stages of the latter, and the causes and remedies are the same in each.

It is generally believed that debility is a predisposing cause of the potato rot, and usually, if not always, preliminary to its attacks. It may be induced in various ways:

1. By planting small and imperfectly matured tubers.-Tubers may be small in consequence of the feeble constitution of the plant, or because they were formed late in the season, and, therefore, had not sufficient time to attain full size and maturity. It is a law well established in the vegetable kingdom, and also in the animal, that like produces like. By this it is not meant that the offspring will be exactly like the parent in every particular, but simply that it will more resemble it than any other variety. If, then, we plant a tuber which is small and the result of feeble growth, we cannot, by any principle of reproduction, expect anything, as a general result, but a small and feeble offspring. This may not always be fully realized at once, but sooner or later it will come.

In the case of imperfectly matured tubers it is well known by all that potatoes, when used before they are ripe, are unpalatable, hard, and watery. These qualities result principally from the absence of starch, which, according to the analysis of Professor Payen, made with seven varieties of the potato, constitutes about seventeen parts out of the twenty-six parts of the whole solid or dry matter contained in the tuber-seventy-four parts of the tuber being water. The starch, when converted into sugar by the process of germination, furnishes food for the young plant in the early stages of its growth, and before it has thrown out roots by which it may draw any nourishment from the earth.

Now, if the tuber does not contain a proper amount of starch, in consequence of its imperfect maturity, the young plant cannot get the necessary nourishment, and of course must be feeble and stinted during the period of its growth; and this shock to its constitution cannot be overcome by any amount of fertility of soil from which it may afterwards derive its food. Hence imperfection and debility will be the result, and a foundation will be laid for future disease. A remedy for this debility may be found by yearly selecting and planting full-sized and perfectly matured tubers.

2. By planting tubers cut very small.-Tubers are often cut into very small pieces, containing perhaps only one or two eyes at most. It is obvious that pieces so small can contain only a very small quantity of starch for the nourishment of the young plant. It must, therefore, struggle through this critical period of its existence in a starved condition, and we cannot reasonably suppose that it will ever be able to overcome this want of "a good start" at the commencement of life, by any subsequent cultivation, however good it may be. "Small potatoes," says C. E. Goodrich, "and those cut very small, are certainly very ob jectionable in a physiological point of view. The sprouts, until they are well out of ground, and their leaves expanded, draw all their food from the mother potato. If this is small, or has a great many eyes in proportion to its size, it cannot throw up strong shoots."

And further, admitting that the pieces are sufficiently large to contain all the starch necessary for healthy germination and growth, yet in many instances they suffer a partial decay before germination, while lying in the ground, and the starch is changed from its healthy condi tion, in consequence of the absorption of water and noxious substances, through the lacerated organs of the cut tubers.

The tuber is a thickened portion of a branch, growing out of the stalk

under ground, and having the power of retaining life for a time after the parent plant has perished. It is not a root. If a shoot of the common currant bush should thicken at the end and swell into a tuber, its woody substance being changed into nutritious matter, and its buds retained on the outside, it would precisely correspond with the tuber of the potato. The eyes of the potato are only the buds of the branch.

The buds of a shrub or a tree are connected with the woody tissue and pith of the branch, by the medullary rays, so that a circulation is constantly kept up between the interior and the surface. The buds (eyes) of the potato are connected with the interior of the tuber in a similar manner; and if the rootlets are cut the functions of the organs are impaired, and they cannot perform their offices of absorbing nutrition from the tubers as they would if they had not been injured, and, therefore, the young plant is weakened. It is true that the potato has naturally such vigor of constitution that it will grow even from a peeling not more than an eighth of an inch in thickness, but it must be apparent to every careful observer that, with such deficiency of support, it could not long maintain its health.

To guard against the danger of decay of the tuber in the ground before germination, it is covered with a coating which is nearly impervious to all fluids, so that the matter which is contained within is carefully preserved from contact with all substances which would unfit it for sup plying healthy nourishment for the young germ which it is intended to support. "The fact is," says C. E. Goodrich, "the potato has a less permeable skin than any other culinary root. This impermeability forbids the transmission of ordinary liquids through it; hence it is the last root to wither in the sun and the last to absorb moisture. The withering of potatoes in ordinary cases in spring is the result not of transpiration of their juices, but of their loss by germination.”

From these statements it appears evident that the greatest health and vigor of the plant are secured by adopting the course which nature pursues in reproducing the plant in its native locality, or by planting fullsized and perfectly matured tubers whole. "The custom of planting cut potatoes," says Professor von Martius, "instead of whole ones, should in no case be adopted, as without doubt it has exerted an influence in the deterioration of the race."

3. By long cultivation of the same variety.-It is generally believed that, by long cultivation of any variety of the potato, it at length becomes less prolific, and is weakened in its whole constitution. Although the fact of deterioration is admitted, there is much difference of opinion with regard to its cause. If the cause could be perfectly known, a very important step would be taken toward finding a remedy by which the debility might be removed.

Some persons suppose the reason of the deterioration to be, that the elements of the soil have been exhausted, and that the potato really becomes weakened for want of proper food; a part of the deterioration is also attributed to bad cultivation. It is said, in reply, that this is no doubt true to a certain extent, but that a change of locality and culture will not restore its original vigor. "I have in several instances," says T. A. Knight, "tried to renovate the vigor of old and excellent, nearly expended varieties of the potato, by change of soil and mode of culture, but I never in any degree succeeded."

In addition to this, it is contended that the deterioration is owing really to exhaustion of the vital energies of the plant, by reason of age; that all created beings, whether plants or animals, have a beginning, a maturity, and an end; and, although the end may sometimes be much

deferred by various artificial means, as good culture, &c., yet death is inevitable. John Townley thinks that the potato raised from the seed is in its prime or full maturity from the fourth to the tenth year, and after this it generally declines, and will, in the course of years, "run out," and finally become extinct. The power of propagating the potato from the tuber appears to be only a temporary device, by which a desir able variety may be continued beyond its annual period of life for a few years, or until other good varieties may be produced and perfected from the seeds.

It is asserted, further, that the renewal of a plant by a bud or a branch, as in the cultivation of the potato from the tuber, is only a continuation of the same organization, or old variety; that the earth in the case of the tuber, and the stock in the case of grafting a branch upon it, "can give nutriment only," and "not new life;" and that it is the seed, which has been influenced by the pollen, that originates a new plant which differs from all that have been created before it or will be created after it, being endowed with a vital principle peculiar to itself, and which no other plant of the same species, or any other species, can impart or perpetrate beyond a certain limited period of life. "The enlture of the potato constantly from the tubers," says C. E. Goodrich, "and almost never from the seed, added to the carelessness with which that cultivation has been conducted, has certainly tended to enfeeble it."

Admitting that this view is correct, one remedy at least for the debility must be found in raising new varieties from the seeds of healthy plants. If vigorous varieties cannot be found at home, they must be obtained from their native locality. The seeds should be sown in beds or boxes like tomato seeds, in early spring, and then transplanted into well-prepared soil, where they may mature their tubers. It is recommended to set the stems deep, or about one-third in the ground, that they may not dry up, and that the tubers which grow from them may be properly protected. Some tubers of tolerable size will be formed the first year, and of full size the second. Only a few will prove worthy of being cultivated.

New varieties may also be produced by cross-breeding, which consists in fertilizing the pistils of the flowers of a desirable variety by the pollen of the stamens of another variety, the qualities of which we wish to impart to the former. From the seeds produced by the fertilized plant new varieties may be grown possessing, in some degree, the qualities. of both, and some may be better than either. It should be remembered, however, that all new varieties are not equally hardy, some, from a natural weakness of constitution, being more inclined to rot than others, and therefore inferior, in this respect, to some older varieties; but these cases are exceptional. If the practice of renewing the potato from the seeds at proper intervals should be adopted, the debility aris ing from long cultivation of the same variety would be avoided.

4. By cultivating in soils not containing the elements necessary for its growth. It is found, by'an analysis of the solid or dry matter of the tuber of the potato, that about forty-four parts out of one hundred are carbon; and of the one hundred parts of the ash of the tuber, about forty-eight parts are potash and twenty-one parts phosphates. It will be seen, therefore, that the elements which form a large portion of the solid part of the potato are carbon and potash. We have also previously shown that carbon and lime abound in the soil of the table-lands where the potato grows wild.

If these elements are wanting in the soil in which we desire to cultivate the potato, (and this can be ascertained by analyzing it,) they must be

supplied by artificial means, as the only proper remedy for weakness induced by a deficiency of nutritive elements. Carbon may be supplied in abundance from decayed vegetable substances, as leaves, turf, and muck; potash may be found in ashes, lime, and gypsum, and the phos phates in bones. All experience proves that these substances, combined in proper quantities with sand and loam, form an admirable soil for the growth of the potato; and preparing the soil in this way constitutes an important part of good cultivation.

5. By excessive stimulus from strong and concentrated manures.-It is a fact of common observation that plants which are subjected to high cultivation do not ripen and consolidate their tissues so thoroughly as those of more moderate growth. Fruit trees cultivated in rich gardens, and making large growth of wood, are certainly not capable of enduring so great climatic changes, without injury, as those which grow in poorer soils.

The case is the same with the potato. The tubers are inflated and watery, in consequence of a deficiency of starch, which should have been elaborated in the leaves, and properly prepared for plant growth; the organs are overworked and surcharged with stagnant matter, and the whole plant feels the delibitating influence. This effect may not appear in the first or the second year, cr indeed in many years; but, like the abuse of the human system by excesses of any kind, it will surely appear at some time. This anxiety to raise large crops, and to work the plant beyond its capacity by excessive stimulus, is very injuricus, and will, in the end, destroy it. Moderate stimulus produces a firm texture and vigorous constitution.

6. By effect of climate, or sudden alternations of heat and cold, and of wet and dry weather.-Few plants, even of those which are native, will endure great extremes of climate without injury. The potato, although a very hardy plant, is in some respects tender. The eficct of sudden cold after great licat is to paralyze the organs which elaborate the sap for the nourishment of the plant, and unfit them for performing the offices in the vegetable economy for which they were designed.

The pores (stomata) are the breathing passages of plants, and are found on the leaves and stems in great numbers. Through these the super fluous water taken up by the roots is eliminated. In wet weather they are open, and in dry nearly closed, to prevent too great evaporation. Too much wet after hot and dry weather, or excessive heat after drenching rains, has an effect very similar to too great cold. The spongioles of the roots, after heavy rains, absorb large quantities of water containing the nutritive clements very much diffused. The leaves and stems also absorb additional quantities, containing little or no nutrition. The elaborating organs become gorged with fluid, and the tissues tender. If a sudden transition to great heat and dryness occurs at this time, the pores are closed and evaporation is checked. The fluids are retained in a stagnant condition in the tissues, the elaborating organs are obstructed, the leaves become pale and sickly, and finally decomposition and disease ensue. The effect here described is often seen after heavy rains, blackening the foliage of the potato in every part.

Climatic influences cannot, of course, be entirely overecme, but the most natural remedy for the disease, resulting from want of adaptation of climate, is to cultivate this crop in that portion of the year which combines in the greatest degree, in any given locality, the conditions of uniformity of a proper temperature, serenity of atmosphere, and the requisite amount of moisture. From what we have learned of the habits of the potato, it appears that an average temperature of about sixty degrees