Page:Popular Science Monthly Volume 25.djvu/690

674 begin with some thoughts upon organic physiology in its general relations, as preliminary to the special results desired.

The animal frame is a material organism which is kept in activity by certain energies. These energies are constantly exhausted and constantly renewed, but their vigor at any fixed period is limited, and can not be indefinitely increased. The force received from without is variously employed within the organism. It acts successively as muscular, nervous, temperature, and reproductive energy. But being limited in quantity, if it be employed by any of these organic agencies, its use by the others is restricted or prevented. Much of the energy received is used up in alimentary processes—the pursuit, seizure, mastication, and digestion of food. Only the excess over this is available for the other organic necessities. And, if this excess force be exhaustively employed by any one of the bodily agencies, it becomes unavailable for the others.

The fact here briefly stated is one which might be illustrated by numerous instances drawn from the lower animal world. A very interesting example of its influence may be perceived in the organic conditions of the ants, and, to a lesser extent, in other insect tribes. Ants, though possessed of all the organic force agencies, do not employ them all in any one individual. The males and the fully developed females exhaust all their life-force in reproduction, with little display of muscular and none of mental vigor. The remaining members of the tribe, divided into workers and soldiers, devote all their life-force to muscular and mental labor. They are, functionally, females, but their organic energies are entirely withdrawn from the reproductive agencies, and devoted to other life-purposes. Of these two classes the workers appear to have the highest mental development. The soldiers understand the whole business of fighting, but beyond that they seem incapable, and take no part in the nest-building, the food-gathering, or any other of the ant-industries. Indeed, they are too dull or too proud to even feed themselves. They would starve unless fed by the workers or slaves. And in the occasional ant-migrations the soldiers are carried bodily by the workers, neither resisting nor aiding in the labor necessary to move their high dignities. In the workers the exercise of muscular force seems to be accompanied by a considerable employment of mental energy, since they perform many actions which appear to indicate an advanced intelligence.

This illustration from the ants might be extended to the bees, and to some other insects. We might also describe the very curious and diversified separation of function in the members of the Siphonophoræ, or compound polyps. But there is no occasion to multiply illustrations. If we ascend to the higher animals we find no such division of function. And yet circumstances largely govern the extent to which the organic force is applied in any one direction. But we must make here a distinction which facts yet to be described render very