Practical knowledge of the results of cross-fertilization may almost be said to date from the latter work. This knowledge has been extended and epitomized in Focke's "Die Pflanzen Mischlinge." Darwin's two works here cited may safely be counted the cap-stone of a century of progress in science of horticulture. In another branch of this science, a monumental work has recently appeared in De Candolle's "Origine des Plantes Cultivees." This book, with the discussions which it has aroused, gives us a compendium ■ of the known ancestral forms of cultivated plants, and is highly suggestive of future progress.

This science- of horticulture is many sided, and sometimes ill-defined. The better part of it may be expressed in the phrase, "Variation of plants under culture and selection." In many cases, the effects of the simplest operations of culture are not well understood. The mere accident of variation in soil may be found to modify plants, sometimes profoundly. Sandy soils tend to produce high colors and high flavors, in consequence of their greater warmth. Peaches are nearly always richer in color and flavor on such soils than on wetter and stronger soils, other things being equal. Squashes often show remarkable differences when grown upon different soils, and these differences can sometimes be perpetuated for a time by seeds. The writer has produced from the same parent squashes so dissimilar, through the simple agency of a change of soil in one season, that they might readily be taken for distinct varieties. Peas are known to vary in the same manner. The ends of a row of peas, sown of the same kind, last year gave the writer marked variations, due to differences in soil. Many well known varieties are less distinct than were the two extremes of this planting. Light soils also tend to shorten the period of growth. Upon such soils plants mature earlier, and are consequently hardier.

This is one of the earliest lessons which the fruitgrower masters. It is not known if this character, attained from soil, is transmissible to offspring. Light soils tend to make most plants smaller. Pea growers characterize soils as "good" and "viney." Upon the latter sort the plants run to vine at the expense of fruit, and their offspring, for two or three generations, have the same tendency. Light soils decrease the tendency to vary. Of many plants, seedsmen secure best seeds from such soils. These seeds are more likely than others to "come true," to reproduce their parents closely. Upon heavy and rich soils varieties tend to "break," or to assume various forms ; and this "breaking" is the inception of new varieties. Our general knowledge of the influences of soils upon plants, of which these illustrations are trifling examples, is wholly fragmentary.

Change of latitude often works great change in cultivated plants, and yet the change is so obscure as to lead good observers to declare that acclimatization does not exist. The most apparent effect of removal through degrees of latitude appears in the stature of the plant. Northward, plants are smaller, dwarfer than southward. Corn is a familiar example. In Canada and the Northern Stales the species is represented by the flint or "Yankee" corns, while in the Middle or Southern States the varieties are all dents. In Canada the average height of corn is six feet, against twelve feet in the Gulf states. Moreover, recent experiments show that flints become dents, and vice versa, in a few generations, through a simple change of latitude. As a rule, dwarf plants are relatively more productive than large ones, and as more plants can be 'grown upon a given area, it follows that they give greater total yields in field culture. But there must be a point beyond which dwarfing is unprofitable, as diminutive plants can produce little. In other words, there must be for each species a most profitable ratio of size of plant to quantity of fruit. Experiment can determine this ratio, and must then seek to produce it.

In general, transfer in latitude seems to be the readiest means to accomplish this object. When the latitude of most profitable production is determined for each species, the plant can there be propagated for dissemination elsewhere. Variation in reference to latitude is apparent in many directions. Color, flavor, habit of plant, and even variability itself, all are modified in many ways through laws of latitude, altitude and climate which we cannot yet announce.

Plants respond in a wonderful manner to man's care through direct selection. "Like produces like " is to the gardener a law of circumstances and conditions. If the phrase were strictly true, we should expect no improvement in varieties. We should still know only the old Cherry tomato and the single white or pink petunia. When once a species begins to vary, is " broken," man's power over it is marvelous. In a score of ways it responds to his touch. Yet, strangely enough, there are few explicit laws known concerning plant breeding by simple selection. It is tolerably well known that the character of offspring is determined by the character of the parent as a whole, rather than by that of any individual part which we may desire to improve. Small tubers of potatoes from large or productive hills give larger yields than large tubers from small hills. An experimenter labored in vain for many years in the endeavor to improve the tomato by selecting seeds from best fruits, but when he began to select seeds from fruits of best plants success came rapidly.

So it appears that even so simple a matter as "selecting the best" may result in poor practice.

Darwin's work on Fertilization in the Vegetable Kingdom suggests an attractive and profitable field of horticultural inquiry. His experiments refer particularly to the immediate effect of cross-fertilization upon the productiveness of the fertilized plants, and they first called attention to the great importance of crossing to the plant itself. But it is only a step from this labor to the larger one of producing new and distinct varieties through crossing and hybridization. Lindley wrote that "hybridizing is a game of chance played between man and plants." It has now become a tolerably successful practice, however, and is a subject of common discussion ' among the better cultivators. Notwithstanding this, and the elucidation of many recent experiments, Lindley's phrase is not yet outgrown. Even the best of operators assume no exact knowledge. We simply know that if a cross or hybridization is affected between varieties or species of given char acters, the offspring will likely combine more or less of the features of both, in varying degrees.

Many examples of remarkable results of cross-breeding are proof that there are great possibilities in it for the horticulturist.. Common literature is full of the assumed achievements of the practice, yet, in fact, our vegetable and fruit plantations know remarkably few good crosses and hybrids. In ornamental plants instances are common, and among the orchids they are numerous and commercially important. Many suppose, and with reason, that all or nearly all plants are capable of great improvement through amalgamation. There is certainly more reason to hope for great results of cross-breeding among vegetables than among animals, for the reason that domesticated kinds are far more numerous. It may be a surprise to many to learn that the world still possesses great numbers of wholly wild species of plants which give promise of yielding important edible parts if once brought under the hand of the cultivator. In fact, there is every reason to believe that more edible fruits and kitchen vegetables are still unknown to cultivation than are now grown by man. Dr. Masters declares that "there are more vegetables to be had for the search than are at present in use.

The difficulty is rather in overcoming the prejudice against new edibles and in getting them cultivated, than in discovering them.*' There are only about 250 species of plants cultivated for food for man among civilized peoples, yet the United States possesses within its borders certainly 75 wild species worthy of cultivation and improvement. In truth, America has so many wild plants of economic promise, that it appears to be safe to say that if the cradle of the race had been rocked in the Mississippi valley, the world would now have been far richer than it is in edible plants. Already our own woods have given us great treasure. All our grapes of out-door culture, all our raspberries, blackberries, cranberries, best gooseberries, and possibly our strawberries, have been improved from wild plants of our woods and fields. A new race of plums and of currants, indigenous to our soil, are now gaining prominence. And the untried resources in the way of wild grapes, plums, cherries, whortleberries, currants, gooseberries, and other things, are numerous. It is certainly not a bold prophecy to say that another century will bring many species of fruits into common use of which we now know nothing.

The last half century of progress in American horticulture is of itself sufficient warrant for such statement.

One of the best measures of the status of a science is to be found in its vocabulary. Judged by this measure, the science of horticulture is yet in first infancy. Its terms are for the most part vague and inadequate, and many important conceptions and operations, capable of expression in a substant-ive, must be conveyed in a bungling phrase. It is not to be supposed that this meagre vocabulary means that the laws of horticulture are past finding out, or that ability is lacking to discern them. It only illustrates the fact, patent in so many directions, that the best talent has been given to agricul-tural professions less freely than to others.

L. H. Bailey.