Page:Popular Science Monthly Volume 51.djvu/683

Rh by those saplings which develop from underground parts often quite distant from the parent trunk; and most of the higher plants can be reproduced in cultivation by cuttings, slips, etc. The sexual reproduction has been developed from simple forms in low plants—for example, the seaweeds—to a state of complexity among the flowering plants which is equal to that among the higher animals. Though there are no superficial resemblances between the sexual reproduction of animals and that of plants, yet the processes are intrinsically the same. The differences are mainly superficial, like those in the means of conveying the male elements to the female elements. The male and female elements in plants are very different from one another, just as in animals, much more different from one another than these elements are from the corresponding elements among animals. In the one kingdom as in the other fertilization takes place when a male element fuses with a female element. So much alike indeed are the microscopic processes in the two kingdoms that much light has been and still may be thrown upon the great general questions of the influence of parents on offspring, of heredity, of descent, of development, by the microscopic study of the phenomena of fertilization and development among plants. There is, therefore, a science of embryology cultivated by botanists which is of almost equal value to man with the science of embryology cultivated by zoölogists.

The microscopic study of the purely vegetative as distinguished from the reproductive parts of plants reveals certain mechanical principles of structure which engineers are now just beginning to follow in their buildings, especially those constructed of materials which in large masses resemble in physical qualities those microscopic elements of which plant structures are composed. We see that the stems of our native trees and those of the palms and others of warmer climes are really frames consisting of long, slender, light yet strong and elastic beams so joined together that they form a structure capable of supporting great weights in spite of the force of gravitation, and so buttressed at points of branching and where the aerial structures spring from their strong foundations in the soil that they are able to resist the really tremendous strains brought to bear upon them by high winds. These principles of buttressing, of accurate balancing, of avoiding sharp angles by the substitution of curves, of a light, elastic framework of great strength, which are common to all the larger plants, we see employed in those buildings which by reason of height, position, or purpose are exposed to great strains. For example, there is more than a fancied resemblance between the Eiffel Tower and the steel lighthouses of our coasts to the buttressed, spreading bases of our elms.