In order to illustrate the fundamental characteristics of an organic structure in general, we will begin with comparing it with what it most resembles, namely, a complicated mechanism. The likeness is so striking that the very dissimilarities become instructive. First of all we notice the parts of which the machine is composed. What these parts are to the machine the members and organs are to the organism. Every part, like every organ, has a certain duty to perform which it incessantly repeats. The work of the machine is divided among the parts as that of the organism among the organs. As the organ, so the part of the machine[139] can do its share only when in right position and in right order.
The most obvious similarities are now exhausted. The parts of the machine are actuated by external, but the organs by internal, forces. The organism is a living machine. No organism, whether organic or mechanic, labors for its own sake. Every such apparatus exists for somebody’s use. But while those that employ a machine stand in outer relation to the same, those who utilize an organism are beings that themselves constitute the organic machine-parts. These are not composed of dead atoms, but of living individuals. The organism is a society which puts the organic machinery into service. It is the social tie that connects the individuals which otherwise would be a multitude of isolated beings.
In all organisms there are as many organs as actual wants among the individuals that compose it. Because these individuals are kindred, they have common needs and are therefore able[140] to use the same organ. Every particular individual requires the assistance of all the organs and must therefore stand in such relation to them all that he can utilize the work of any one. But he himself enters as a working member only in one organ, whose work is the only one he can immediately press into his service, and even this only in certain cases. All other organs stand in more or less distant relation to him. How, then, will he be able to utilize them? Only so that the organs make themselves present in his own organ, and, so to speak, reach him their different products. Like every citizen in a community, each organ ought to have a system of circulation throughout all the other organs to transfer the results of its work where it is needed. If, however, each organ were provided with such a distribution agency this would be an extravagance inconsistent with the concentration of forces that the very idea of an organism implies. Instead of many such systems we find[141] therefore in every organism but one, whose sole purpose is to circulate the products of the various organs, and thus, so to speak, make each organ represented in every part of the whole community. We find that every organic building is constructed in this way to suit the individuals that form its building-material, and so of course it must be, since it was built for that purpose by the same individuals.
The consequence is that the degree of development an organism possesses is closely related to the state of evolution reached by the individuals which constitute it. The more perfected the organism, the higher and more developed also are the necessities it is able to satisfy.
The way in which independent living beings build such an organic machine may be defined as “division of labor.” Every organism is a union, founded on the division of labor, between a multitude of kindred individuals which thus combine their isolated[142] forces. But a large mass of individuals cannot merge at once into an all-embracing entity. This result can only be reached by a series of higher and lower intermediary units, each defined by its particular share of the total labor.
A closer study of the organisms will show that they all without exception are composed in this way.
The cells in a............