Nucleus

to form cells. These are the smallest units of living matter (Fig. 1). While many plants and animals are single-celled, more complex organisms are composed of colonies or aggregations of many cells in varying degrees of association, different groups of the member cells being specialized to perform specific functions. Thus it has been estimated that the cortex or thin outer coating of the human brain contains

FIG. 2. General schematic diagram of a cell. (From Wilson, The Cell in Develop ment and Heredity, 3 ed., N. Y., Macmillan, 1925. Reprinted by permission.) considerably over nine billion nerve cells, in addition to many cells of other types. The behavior of the organism depends on the manner in which these nerve cells act upon each other and upon the other cells of which the organism is composed. The human being, like all complex organisms, is a great interacting society of living creatures functioning in different degrees of dependence on each other. But as a matter of fact, even the simplest single cell is an intricate organism composed of interfunctioning parts (Fig. 2).

(2) Metabolism. The living state is one of continuous chemical activity. Every organism keeps itself alive by taking in and assimilating combustible materials from outside itself; by oxidizing or breaking down these materials, thus releasing their stored up energies; and by excreting the broken down compounds as waste products. The more complex organisms possess a fairly permanent structure which is built up from part of the assimilated material. The metabolic needs of an organism are always fairly specific, and are also regularly recurrent. Hence each organism is bound rather closely to those natural environments which are capable of satisfying these needs.

(3) Reproduction. Organisms under certain conditions and at certain times are capable of "reproducing themselves," that is, of producing new individuals more or less like themselves. The basic feature of all reproductive processes is cell division-the operation whereby one cell becomes a number of cells. This process is a complicated one in which the structure of the original cell is altered at the time of division so that complete cells are formed of the parts split off. Thus when the one celled ameba by dividing literally becomes its own children, it does not simply fall in two. The new generation comes into being as a result of complex physiological changes in the course of which the specialized parts of the parent animal perform precise functions. In the case of human beings, the processes of cell division which lead to the development and birth of a child are brought about by the fertilization of a female germ cell (or ovum) by a male germ cell (or spermatozoön) within the body of the female.

(4) Irritability and motility. Every organism is intimately and continuously responsive to the energies which incessantly play upon it, and in turn the organism continuously acts upon the environment. The different parts of the organism also act upon each other without rest or ceasing, and as a result of all these actions and reactions the organism is changed and changes other things in a never ending sequence. This continuous external-internal interplay is no doubt an aspect of the fundamental instability of proto

plasm, but it is also an integral feature of the dynamic world to which organisms belong. This interplay of external and internal forces determines what the organism is and what it does. When we investigate the changes that take place within the living creature itself during the process, our concern is with the irritability (or sensitivity) of the organism; when we study the external motions or actions that result, we are interested in the organism's motility. In both cases we are dealing with essentially the same process, though from different points of view. The first interest might be called biographical or personal, the second historical or behavioristic.

The place of birth in the life process

The organism does not wait until it has been born to begin functioning. The intimate interdependence between biological and environmental factors long predates the moment of birth. This fact is ignored when attempts are made to distinguish inherited from acquired traits by determining the traits which are present at the time of birth. Birth in no sense constitutes the beginning of life processes-i.e., of biological-environmental interplays. The child was alive for nine months prior to the time of its coming into the world, and the germinal materials from which it developed were alive before that. Life comes, through germ cells furnished by the parents, from a dateless past. Nor can the real beginning of an independent existence be dated from the moment of birth. The baby, the child, and even the adult are at all times dependent on persons and things. outside themselves for the realization of their own natures and even for their very existence. Nor does the infant display at birth anything but the vaguest intimations of personality and character. To start with, he is hardly more than the insistent embodiment of certain needs; and precisely what he shall eventually become depends as much on how these needs are satisfied as on the nature of the needs themselves.

Children do not come "out of the nowhere into the here" by sudden and impersonal fiat; they are born as a result

of complex socio-biological interactions between organisms. The process by which children are conceived, formed, and brought into the world is biological and social in all of its phases. It is biological because it goes on at every point in terms of the primary life processes described in the preceding section; and it is social because it is affected throughout by the attitudes and behaviors of persons who function as cooperating members of a group. Birth initiates new physiological rhythms (respiration, feeding, etc.), but these activities assume and require the new environment (itself social as well as merely physical) into which the organism is thrust. In addition the organism acquires a new social status upon being born. The time is one of alteration and therefore of danger, but in this respect it does not differ significantly from other periods in the life history of the organism-as, for instance, (1) the moment of fertilization, (2) the first three or four years of life, or (3) the period of adolescence which begins early in the second life decade. Although these foci of change will be discussed at greater length in the pages that follow, a few words concerning each of them at this point are appropriate in order to show that the changes incident to birth are paralleled in the history of the organism by other changes of quite equal importance.

(1) At the moment of fertilization, when male and female germ cells unite and initiate the processes of cell division which finally result in the development of a full-fledged human being, the main hereditary outlines of the individual's equipment are laid down-in no detailed and arbitrary manner independently of all further eventualities, as we shall see, but within limits nevertheless. (2) During the first three or four years of life, including the period of nine months in the womb and the years that follow, the organism comes more closely and pervasively under the influence of its physical and social environment than during any succeeding period, and that too at a time when its weakness, immaturity, and ignorance render it exceedingly susceptible to outside pressures and influences. During the time it spends in the even environment of the womb, the broad outlines of its bodily structure are determined, and the basis

laid for many of the behavior patterns of later life.* Nor are the first years after birth less important, for it is then that children form those drives towards mastery or submission, those curiosities, apathies, interests, and aversions, those habits of cleanliness, carefulness, and attention (or their opposites), and those countless other traits and behaviors which so often last them through the years and mark them off as distinct from other persons until their dying day. (3) During adolescence the life régime of the individual is almost completely reorganized. The sex organs mature, and their secretions initiate physiological changes which transform the child into a fully sexed human being. The bodily attributes of sexual maturity are disclosed, the individual becomes capable of reproduction, new and often disturbing interests in members of the opposite sex appear, vague but powerful romantic yearnings are often experienced, and the pace of life is quickened and its poignancy increased.

Interfunctioning of physical, biological, and social factors

The life processes of human beings may be studied from many different points of view, as is shown by the existence of the sciences and arts which deal with one phase or another of human behavior. It is essential to remember, however, that concrete human living is not ordered in exact accordance with the abstract principles of any of these disciplines.f

*By a behavior pattern is meant some specific organization of response, as the thrusting out of the arms when one has stumbled, or the motions one goes through in signing one's name. The number of behavior patterns displayed even by simple organisms is very large.

†Physiology, psychology, biology, anthropology, sociology, etc. (as their names imply) are really logical systems-i. e., they present theorems (in the form of "facts" and "principles") which flow from basic assumptions or postulates entertained largely for the sake of their organizing power. These assumptions appear in the systems as: (1) definitions; (2) methodological procedures-accredited ways of experimenting, presenting data, etc.; (3) notions of relevance and cogency-accredited canons for the inclusion and exclusion of data. Logicians hold that one or more undefined terms are also necessary to constitute a logical system.

This section must not be read as a polemic against logical systems of the kind described. It is rather a plea for a more comprehensive system from which theorems will flow whose point of reference is "John Doe" rather than "Nature," "Man," "Mind," "Society," etc.