The perpetuation of the greater portion of the known species of plants is directly by their seeds, which in their wild state they perfect with great uniformity; but when cultivated, the vital forces are often disturbed, and a portion is directed into other than the natural channels. The effect of this we see in the double flower, and the increased size of many of our fruits. The seeds of so-called improved plants in a great measure become abortive, and we can no longer depend upon them as a means of reproduction, not only because of the want of vitality which naturally belonged to them, but in the course of cultivation there has been such an intermingling of species, as well as variations, that scarcely any variety of cultivated fruit will reproduce an exact counterpart of itself from seed. Therefore we have to resort to other modes of propagation to perpetuate any particular variety. But this disposition among cultivated plants to change from their normal character is often turned to valuable account, for to this variableness we are indebted for many of the estimable fruits and flowers now in cultivation.

It is therefore of the highest importance that the propagation from seed of those plants which are so variable when multiplied in this manner should not be overlooked.

Seeds when perfect contain the rudiments of a plant, together with a peculiar substance which is accumulated at the time of their formation, and designed as food for the embryo plant during its germination; consequently when seeds are to be preserved for any length of time, it is important that they be not exposed to any conditions that will destroy either the germ or that food which is stored up with it for its future use. Under what particular circumstances seeds will preserve their vitality the longest, it is very difficult to determine, as some varieties will remain sound for years, while with others a few days is sufficient for their destruction. This diversity in the vitality of seeds is not wholly confined to any particular genus, but is observable in different species of the same. For instance, the seeds of the sugar maple (Acer saccha-rinum) may be preserved in a cool, dry place for one or two years, and then be made to grow; while the seeds of the silver maple (Acer dasycarpum), if subjected to the same exposure, would lose their vitality in a few weeks.

But there are other things that serve as a guide in the propa-tion of these two species; by observation we learn that the seeds of most of those trees, like the silver maple, which ripen in the early part of the season, if placed in the soil so soon as ripe, will make sufficient growth to withstand the cold of the ensuing winter; while the seeds of the sugar maple, which ripens late in the season, do not germinate until the following spring, even when planted in the autumn. So far as relates to plants indigenous to any locality, it may be taken as a rule, that the proper time for planting the seeds is as soon as they are fully matured.

A cool and moderately dry atmosphere is the best in which to keep most kinds of vegetable or tree seeds, although some will retain their vitality for a long time if immersed in water, provided it is kept at an even and low temperature. This is doubtless owing to the peculiar structure of the seeds, and the exclusion of air and heat therefrom. Those varieties of seeds that are covered with a hard silicious or horn-like covering may be preserved in air-tight cases made of glass or metal, and a similar plan may be adopted with some of those kinds that are naturally dry and are covered with a thin porous covering like the seed of the common onion. But seeds that are of a watery nature, if entirely excluded from the air and exposed to a temperature much above 32°, will soon decay. I am confident that a cool and regular temperature is of more importance than anything that may happen to them hygrometrically; for we find seeds that have been buried deeply in the earth remaining unchanged for many years, yet so soon as they are brought to the surface, where air, moisture, and heat act together upon them, they immediately germinate.

If supplied with the requisite moisture, all seeds grow more readily when near the suface of the soil than when buried deeply, for the reasons just given; therefore we should endeavor to so place them in the soil that the air and heat can reach them, but at the same time exclude the light, for seeds do not require light to assist them in germination.

In aquatic plants the case is reversed to some extent, for they usually sink to the bottom and become buried in the mud, from which they germinate, sending their stems and leaves to the surface, their seeds obtaining the requisite amount of heat from the soil below. But here we again meet with variations from any general rule, because the seeds of some aquatic plants are light and float on the surface, and germinate in this position, the roots descending to the soil, if the water is not too deep. Usually, however, light seeds are thrown upon the shore, and there take root, and their under-ground stems stretch out into deep water.

The proper depth to cover seeds depends very much upon their size and power of throwing up their stems. It has often been observed that seeds should be covered with a depth of soil equal to their diameter; that is, if a seed is one half inch in diameter it should be covered with one half inch of soil, and without doubt this would be the proper depth, provided the requisite amount of moisture could be always maintained; but as it is difficult to do this, especially when seeds are sown in the open ground, this rule is not of general application.

Neither can there be any rule given as to temperature, for some seeds will germinate at two or three degrees above the freezing-point, while others require a heat from 80 to 100°. When seeds have once started to grow, they can not be again reduced to a dormant state without causing their destruction; this should be always borne in mind, for from this cause alone more seeds are annually destroyed than from any other; as they are hidden in the soil, we are apt to neglect giving them an ample supply of moisture at the time of their greatest need. The soil in which seeds are sown should be made fine and permeable, not only to admit air and heat and to retain moisture, but so that the radicle or young root may penetrate the earth without hindrance, and allow the stem to grow upright unimpeded. The soil should be made deep, and of such a nature that the young plant will receive a constant and regular supply of moisture. Nature serves as a guide to us in many of the operations connected with the art of propagation, yet it should be remembered that the sowing of seeds and the planting of trees by man is an artificial operation instead of a natural one; and we follow nature only when it serves our purpose, or as we are compelled to by natural laws.

For nature is so plastic that she allows us to mold her gifts into forms that suit our wants and tastes, confining us only within certain limits, which it is difficult for man to determine. Nature perfects and likewise destroys, and thus that equilibrium is preserved which is observable throughout the vegetable kingdom. If we scatter seeds in every instance exactly as is done by nature, we should not make more than one in ten thousand grow. The wild apple-tree that perfects its thousands of seeds, drops them upon the earth inclosed in a covering that soon decays, and the peculiar acid which it contains, or which is generated while undergoing this decay, destroys the seeds within; not a seed grows unless it is freed from its prison either by its fall or by the aid of insect or animal. This shows the wisdom of nature, for if every seed should grow, the struggle that would be constantly going on between offspring and parent would be such as to prevent the full development of either. This lesson which we learn by observing the apple may serve to guide us in our operations when we come to propagate it and other species of like nature.

For it shows that although nature may fully develop and perfect her fruits, yet she leaves it to us to encourage those varieties which we desire, and by the assistance of art we may multiply these with such rapidity that all our wants may be fully supplied. [to be continued.]