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be so.

Every part of an organism has its function to perform, and the value and significance of that function are to be determined by reference to the part which it plays in the life of the whole. It is not for the sake of the leaves alone that the roots of a plant exist and perform their function, nor for the sake of the stem that the leaves exist. But each one,-leaves, root, and stem,-has its function to perform in the maintenance of the whole plant of which each one is a constituent part. Not even the seed or the fruit is an end in itself, though from man's point of view it may seem to From the biological point of view the function of the seed is merely to perpetuate and propagate this particular kind of plant life. In like manner we may say of every organ or part of the human body, such as heart, lungs, teeth, muscles, nervous system, etc., that no one of these is an end in itself for the sake of which the others exist and perform their function. Each one exists to perform some function which enables the whole organism to maintain itself upon the earth better than it could without this organ. The relation of parts within an organism is sometimes expressed in this way: Every part of an organism is both means and end to every other part.

(2) The organism is a self-maintaining system; it possesses all the functions necessary to the maintenance and perpetuation of itself.

A stone cannot be said to be an organism; it is not a self-maintaining system. While suffering from the disintegrating influences of the environment, it has no specific method determined from within itself of making up its losses. But the plant is constantly taking elements of moisture and nourishment from the soil and carbon dioxide from the air to make up for losses sustained by evaporation and excretion.

(3) The organism is characterized by a law of determination from within.

In the case of the stone, its size, shape, etc., are deter

mined by no specific inner law, but by external forces. But the plant and the animal, while modified in many respects by the influences of the environment, are nevertheless expressions of some more or less specific inner law of development. Plant a bean and you expect a vine of about a certain height, size, and shape, with leaves and stem marked by well-defined characteristics, and blossoms and seeds which you can describe in advance of their appearance. Plant an acorn and you expect an oak with all that is characteristic of that monarch of the forest. Hatch a hen's egg and you expect a chicken and not a hawk. In all these cases there is a specific law of development which no amount of external force can set aside, however much it may modify the final resultant.

3. ADAPTATION BETWEEN ORGANISM AND ENVIRONMENT. (1) Meaning of adaptation.

a. Activity of external factors.

We have spoken of the organism as a self-maintaining system, characterized by a law of determination from within. Before we can see clearly the function of consciousness in the life of the organism, we shall need to develop a little more fully the meaning of this statement. In the first place, we must not suppose that any organism is wholly determined from within. There are also significant forces of the environment constantly acting upon it. These may be favorable and necessary to the life of the plant, if plant it be, or they may be unfavorable to its development, and possibly even destructive. The plant requires from the environment light, heat, moisture, elements of nutriment, etc. To be sure, some one of these may be present in such intense form, as is often the case with heat, that the life of the plant is destroyed. But, take any one of them away, and the plant must perish in spite of all its inner tendencies. We see, then, that the life of the plant depends upon the existence of a constant stream of external influences which affect it in various ways.

b. Activity of internal factors.

In the second place, when we turn to the other side of the question for a moment, we can see that the law of determination from within is the very real expression of inner forces which have to be taken into account. The rock and the plant may be surrounded by the same external forces, but they are affected differently by them. The plant has a way of responding to certain of them which results in life and growth. Again, two plants grown side by side and subject to the same set of external conditions may differ as widely as the rose and the cabbage. While it is true that the external conditions are necessary, it is evident that the form of the plant is due to something other than these factors. It must be due to the operation of a law of determination from within.

c. Interaction between external and internal factors. Our analysis has tended to make clear the fact that the life process involves two sets of factors, the outer and the inner. Life and growth are dependent neither upon the one set nor upon the other exclusively, but upon the coöperation of the two. A bean may be kept away from the moisture for a year or more and it will not develop. It needs this influence from the environment in order to "realize" itself. But when it is supplied with the proper external conditions to induce growth, its growth will be in harmony with the inner law of its own development. The materials will be organized into a characteristic form of life the stages of whose development and the leading characteristics of which we can predict. Our illustrations have been drawn from plant life, but the principle is the same for animal organisms. The life, growth, and continued existence of the organism, whether plant or animal, depend upon the proper interaction between internal and external factors. So long as there is preserved the proper equilibrium between these two sets of factors, so long as they coöperate with each other, the life process goes on, and we have a self

maintaining system, or organism. Destroy this equilibrium and the organism will soon come to an end.

d. Further interpretation of organism and of adaptation. It is, then, a fundamental biological fact that the life process depends upon the proper interaction between inner and outer factors in some center for their coördination. Such a center we call an organism, and the process of right coördination we call adaptation. From the point of view of the biologist, then, an organism is a center for the coördination of inner and outer forces in such a way as to further the life process, and, in turn, this furthering of the life process is adjustment, or adaptation.

(2) Law of reaction.

If we speak of the interaction between organism and environment primarily from the point of view of the part which the organism as an already organized structure plays in it, we call the process one of reaction. As the psychologist is interested in the organism and its conscious processes directly and only indirectly in the environment and its forces, he uses the term reaction instead of interaction.

The relation between the inner and the outer forces in the life of the organism may be formulated in simple terms somewhat as follows: The life and development of the organism depend upon the proper reaction of the inner factors upon the outer,1 the outer serving both as stimulant, or excitant, and as means, or material. Thus, food is to the animal both an excitant calling forth some reaction on his part, and it is also material selected from the environment to be used in the maintenance of the life of the organism.

The law of reaction has been formulated in most general terms applicable to all organic activity as follows: "All stimulations to living matter,-from protoplasm to the highest vegetable and animal structures,-if they take effect at all tend to bring about movements, or contractions, in the

1 Sully, Teacher's Handbook of Psychology, pp. 77-85.

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mass of the organism. Mr. Baldwin calls this the law of dynamogenesis. More briefly stated it is as follows: "Every organic stimulus tends to express itself in movement." Thus the tiny amoebæ, unicellular organisms in the form of minute droplets of protoplasm, are capable of responding in characteristic ways to the presence of light and food. Even the plant bends toward the light. The lives of the familiar animals furnish illustrations without number of the operation of this general law, which the reader can easily supply.

(3) Function of reactions.

The biologist views the organism as a device for the execution of movements in response to stimuli. This capacity of the organism is fundamental to its very nature. It is only through reactions that adaptation, or adjustment, is effected between organism and environment and life is maintained.

From the biological point of view every form of life that can maintain itself has a right to live. The weed and the snake may not for us, and from our purely human point of view, have any value or subserve any end. But we may not inject our limited point of view into the biological process. Nature is "interested" in every one of her living forms. Hence the primary and fundamental end of every organism is self-preservation and perpetuation of its kind. We have seen that this can be secured only through the proper interaction between the inner forces of the organism and the outer forces of the environment. These must come into some sort of working terms with each other. There must be adaptation of the one to the other; there must be adjustment between them.

Every organism is, then, "seeking" to realize itself through a process of adjustment between itself and the conditions of its environment. This process is effected through reactions. This is as true for the organism with a mind as 1 Baldwin, Mental Development, pp. 166, 170.

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