Page:Popular Science Monthly Volume 5.djvu/588

570 of the first drop of protoplasm, and the vivification of the first cell, the tendency has been, as the necessary result of natural selection, to concentrate force. In the history of evolution there is no passing from lower to higher forms—no foldings, no involutions, without an increase of power; and by the same law this development must continue until the highest point of physical energy is attained.

Our ordinary discoveries teach us that force can be multiplied by a multiplication of the elements or organs evolving force. The simplest child knows how to obtain two pounds instead of one by putting another weight in the scale; and the electrician obtains more power by adding another jar, or another plate, or another cell to his battery. In like manner Nature has in various directions seized every means to increase and concentrate what for convenience is termed vital force. For there is the same tendency of the forces to aggregation that we see in matter.

Watching the progress as we have ascended the scale from the first evolution of life, the greatest concentration of force yet reached in organic life is in articulate creatures—or, as we may call them, by a name of more general application, segmentarians. A segmentary such as a centipede, a bee, a lobster, or even the humblest worm, is as truly a compound zoary as any other collection of zooids, whether cœlenterate or molluscoid; and no argument is needed to show a physicist that the closely-united segmentarian zoary evolves more force than the looser aggregation of a branch of ascidians, however highly organized the individuals of the latter may be. There is more force evolved from the gigantic oak consisting of such a closely-united system as presented by the nodes, and which is capable of appropriating such volumes of inorganic matter, than in the loose sheets of ulva or protococcus creeping upon damp walls and slimy pools. Again, in physics, we may multiply force, not only by the number of our elements, but by their size and arrangement. In galvanism two large elements or cells may be made to exhibit greater energy than many small ones in the aggregate of equal superficial extent, yet not precisely the same energy. It is modified as well as increased. Organic Nature presents us exactly as good illustrations of this law as the experiments of Mr. Grove and Dr. Faraday.

The first experiment, so to speak, of Nature to multiply force from the cœlenterate or monosegmental creature, the last stage arrived at in our progress, is by multiplying the segments upon one or more axes. When upon more than one, as in annuloida, Nature seems to break down early, on account of the complication of the machinery, and soon seeks greater simplicity. This is attained, first, by selecting one longitudinal axis, and multiplying the units or elements of organization and force indefinitely. In some worms the number of segments is incredible. Instances of iulidæ, according to Mr. Newport, have one hundred and fifty rings, at least during embryonic life; and, by the