In historical perspective the Wundtian period of psychology, following the clue of its antecedents - of Herbart particularly - was structural in its conception; it became functional by absorption of the biological viewpoint. A better description of this change of direction is from static to dynamic psychology,2 for the latter emphasizes an organic force that runs through all of our drives, whether these drives are due to instinct or to motive. The word "mechanism" is misleading. Dr. Healy even chooses the term "dynamisms" to designate the Freudian factors in directing behavior.

It was indicated at the outset that psychology considers the mechanisms and motives of behavior and their organization, giving them ever a naturalistic interpretation. Certain phases of psychology, therefore, will focus upon the mechanisms or dynamisms, as in the neuropsychological problems of perception and response; others will center on the higher motivation processes, as in the Freudian scheme; still others will concentrate on the organization. Gestaltism, for example, is a psychology of organization. All three phases always combine. Psychology is a unit, not compartmentalized; it merely divides its problems in order to make them accessible, and to make them applicable to the varieties and needs of human nature and of human institutions. The rivalry of the psychologies is more 1  See Koffka, K.,"The Growth of the Mind," Harcourt, Brace & Company, New York, 1924; Kohlbr, W., "Gestalt Psychology," Horace Liveright, New York, 1929.

2 See Woodworth, R. S.,"Dynamic Psychology," Columbia University Press, New York, 1918.

apparent than real;1 yet a still greater fusion of complementary methods and programs is essential to further progress.

A most comprehensive problem of psycho-biology is that conventionally summarized as the apportionment of behavior to heredity and to training, to nature or nurture. That mental heredity must follow the clues of physical heredity is certain. With such a novel and definite advance as followed the rediscovery of Mendel's experiments, there arose the hope that the secret of the mental inheritance had been found; and in a sense, it has. From peas to humans, the laws of genetics apply: the genes, with their definite mode of organization and of hereditary transmission, are as responsible for qualities of brains as of the skeletal tissues; they hold from mice to men.2 Like genes breed like genes; but the drawings are made in a composite lottery. The particular genes which appear in our own make-up, and from whence they came, remain uncertain. In one sense, therefore, the problem has been as much complicated as solved. Life remains a chance - our chance in parents and ancestors, and theirs in us. Just how far genetic procedure may be applied in analyzing the mental dowry is still a vexed, though a clarified, issue. The general trend of it all is clear: mental heredity is real though variable; it is carried in the same mechanisms, genes, chromosomes and all. Yet the world will ever have to depend on chance selection for its favored specimens, whether modernly controlled by the route of eugenics or not. Education has its set limitations.

Any psychology with an hereditarian emphasis is certain to proceed differently, in some phases, from one definitely 1 My address on this topic before the International Psychological Congress (1929) appears in The Scientific Monthly, November, 1929.

2 See Herrick, C. J., "The Brains of Mice and Men," Chicago University Press, Chicago, 1926; Wheeler, W. M. 'Foibles of Insects and Men,"Alfred A. Knopf, Inc., New York, 1928.

placing environmental influences as the major determination. The "behavioristic" position (in Watson's narrower sense) has staked everything on environment. Apparently the argument is based on the "conditioning" of the original "conditioned reflex," as exemplified in the Pavlov salivation response in the dog, in which, after salivation is induced both by the presence of food and so arbitrary a stimulus as the sound of a gong, the physiological reaction is set off for a time by the sound alone - an interesting observation, but one with limited application. Another support is found in the small number of built-in reflexes in the human infant, ready to function at birth, and the ease with which a stimulus may be directed to one form of response (fondling) as opposed to another (shrinking). Whether an infant fears or fondles a dog can fairly well be directed if one starts right; and the same is true in terms of fearing snakes and mice. All this is familiar and finds its explanation in the genetic unfoldment of the reaction paths. Yet upon this slight foundation has been reared the monumental structure of a psychology that assimilates all learning to "conditioning," ignores original bent and limitations, and magnifies training to a commanding influence in disregard of specific endowment.

The confusions and ignorings involved in this position are too many to be exposed in a sentence; they illustrate to what glaring contradictions a strict environmentalism would lead. As a fact the trainability and plasticity of the central nervous system - increasingly noticeable as the higher centers or patterns of integration are involved - bring it about that we humans are singularly free from "conditioning," and in that freedom lies the clue to our learning power. Occasionally, perhaps frequently, we may succumb and may even shape the fortunes of habit to our service; but all that is incidental to the "unconditioned" areas of the productive, flexible mental life. What writer would not be delighted to have himself so conditioned from early childhood and by later training that whenever a bell rang or a chord in G major were struck, he would respond by productive composition! A glorious but futile dream, and how inconvenient if the signal came inopportunely!

There is no salvation in conditioning. Indeed the more helpful concept for that process comes from the Freudian angle and receives the name of"fixation," an undesirable and emotionally overloaded attachment or complex or idiosyncracy. It there assumes the complexion of something to be avoided by keeping attachments flexible and in perspective. Yet equally is that an environmentalist conclusion. As a fact there is no phase of the mind's activities, above the most rudimentary, which is not subject to the combined influences of nature and nurture, of dispositioning and conditioning, each rather flexibly interpreted. Even the relative constancy of the intelligence quotient is not wholly a matter of endowment, but results from a relative equality of environmental stimulation; hence the statistical regularity and the individual variability. The superiority of the average I.Q. among the children of the well-to-do as compared to those of the poorer classes, is an example of the dual set of causes. Psychology is so intimately biological that its principles and practices depend upon the issues of patterns more definitely traceable in bodily traits.