Page:Popular Science Monthly Volume 37.djvu/393

Rh in the direction taken when placed under the favoring conditions of culture.

Garden plants illustrate with accelerated force the working of the universal law of compensation. Fruits not only enlarge, hut "become seedless. Therefore, the increase in the size and other modifications in the flowers of such plants as are grown for their blossoms is only in accordance with a general law. An augmentation of floral parts is only a step beyond the increase in size of parts already present, and may be largely a matter of convenience in the arrangement of the parts in the bud. When we remember that any augmentation in the petals, etc., would be seized upon by the gardener, and if possible reproduced, the wonder is that the increase is not greater than it is. It is not claimed that such an augmentation is a direct advantage to the plant, any more than is the exaggerated size of a cabbage-head or the thick, rich pulp of a grape, especially when the cabbage splits open and falls apart of its own weight, or the grape-pulp monopolizes the whole substance, and no seeds result. When the guiding hand of man is withdrawn, cultivated plants soon or late find their way back to a stable condition called the natural form, and are again able to cope with their neighbors, depending entirely upon the conditions attendant upon the wild state.

The point that now calls for our attention is the development of one floral organ out of another widely differing from it in appearance. Augmentation, we have seen, is to be expected, but metamorphosis usually brings surprise. The unnaturalness of this arises in part from the constancy of organs in wild plants, and the general impression that a manifest difference in structure and use must indicate dissimilar origin of the parts. All of the various organs of a flower are now, as before stated, generally considered as lateral outgrowths from the stem, and in a state of nature their number, size, shape, color, etc., depend upon the service of each in the economy of the plant. In origin and early growth, therefore, there is no microscopic difference between the sepals, petals, stamens, and pistils. As shown at the beginning of this paper, by taking the whole range of wild plants, it is not difficult to find all gradations, from the outermost sepal to the central pistil. If these various parts have a common origin—namely, in minute cellular outgrowths afterward connected with the primary axis by a vascular cord—the wonder is that each type is adhered to so closely in the wild forms, and the surprise should be that under the modifying conditions of culture more striking combinations are not found. The petals (that is, the inner whorl of floral envelopes) and the stamens (the outer circle of essential organs) form the boundaries between the two primary divisions of the complete flower. It is here that the line of separation is