living organism. So the proteins of the palpable food-substances which are eaten. Once incorporate in the organism, their action changes and transcends the explanations of sheer physics or sheer chemistry. The channels of interpenetration and transmuting of organism and environment are still unnumbered. Is not our weight part of the gravitation of the earth? Organisms cannot be accounted for or described in terms of the physical laws applicable to the inorganic world. They are alive. Yet they cannot be separated without change from all that surrounds and penetrates and sustains them.1

Besides, the individual animal or plant is not simply itself, but a handing on, a continuance, of the species; and the species is one long and vanishing recessional into a not merely cradling and sustaining, but a constantly insinuating and reciprocating environment. The species lives and functions in the individual. Individual, species, environment are and always have been in and of each other.

1 “There is no sharp line of demarcation between a living organism and its environment. The persistence of the internal environment and its activities is, in fact, as evident as that of the more central parts of an organism; and a similar persistence, becoming less and less detailed, extends outwards into the external environment. An organism and its environment are one, just as the parts and activities of the organism are one, in the sense that, though we can distinguish them, we cannot separate them unaltered, and consequently cannot understand or investigate one apart from the rest" (J. S. Haldane, Organism and Environment, etc. (1917), p. 98).

As with the species and the outstanding individual, so with the living parts of the organic whole. Every cell lives and moves in a living and commingling medium or environment of the total organism, the milieu intérieur. The life of the cell is a metabolism-a living taking from its living and homogeneous environment, a transforming appropriation, and a rendering or reproduction in return-with a breaking down and casting off of that which is exhausted. Each cell shares in the metabolic activity of the whole organism. Together they form a community of life. The behaviour of each is dependent on the behaviour of the rest; and the lives of all are mutually regulated by each other.

Thus metabolism is the keynote of cell-life. One is tempted to apply the word metaphorically to the inter-relations and commingling of organism and environment. The organism absorbs, transforms, and excretes parts of its environment; and what it throws off is absorbed and transformed by the environment in turn. Strict mutuality may be lacking, since the environment can scarcely be regarded as organic or in all respects alive; and often, apparently without imparting of its substance, it affects the organism.

The universal business of all organisms is to get food and propagate their species. Their food and their own organic means of getting and assimilating it may be the main factor in the evolution of the myriad species of organisms with their varied

faculties, from the grass of the fields to the elephants who devour it, and even man.

Still more broadly speaking, the sustaining, conditioning, permeating environment, and the reactions of the organism upon it, control the evolution of all organisms. Every organism fits its environment; and the evolution of species in the past must have held to the grooves of a like fitness, which are channels of possibility. Assuredly, as we find them, fishes cannot breathe in the air, nor land-animals beneath the water. The musk-ox and the polar bear seem to have developed their shaggy coats to meet arctic inclemencies, and would die if suddenly transferred to the equator. Such growths or evolutions, which are supposed to have gone on through uncounted millenniums, are understood inferentially. But that the coercions and opportunities of their environment, while obtaining food and shelter and keeping themselves from being eaten, mould the habits and develop the faculties of every animal, is a daily fact patent to any observer.

Of this coercive development, man, the human animal, was to afford complex illustration in the economic laws which spring in the first instance from his physical environment. Doubtless the means by which men obtain life's necessities go far to shape their institutions and the forms of their social development, as we may note hereafter. Neither the necessities nor the means of satisfying

them are stationary; but together expand and multiply with the advance of society. From the hunting of savages for food and skins, on through more settled agricultural stages, to the furthest and most complicated states of industrialism, such as we labour under to-day-throughout this whole social advance the expanding physical needs of men, and the methods used to satisfy them, do not cease to affect the development of social laws and political institutions. Expanding needs work upon society in correspondence with the machinery and means through which these needs are satisfied. Industrial progress moulds itself to the conditions of environment. Advance is made along the lines of the preponderance of impulse or compulsion, which may operate through the pressure of class on class, or evince itself in riots, industrial strikes, and the application of police or military force.

Through this kind of progress or arrest, the logic of fact, the possibilities of a situation, shake out into some coherent, demonstrative result. Social and political theorizing may help to clarify men's minds, may exert influence, or contribute to explosions; but, whether through explosions or less violent action, they will prove constructive only when agreeing with the faculties and dispositions of men and the possibilities of their environment.

This power of fact, this necessity of the actual situation, works onward, altering social relations, building cohesive human institutions and destroy

ing them; thus working constant change, and itself changing with changing conditions which it has done so much to bring about. Individual genius assists by suggesting outlets and escapements, improved mechanical devices, or a better adjustment of human relations, making for social peace and welfare.

III

COMPULSIONS FROM WITHIN

These constraints which seem to make their impact upon man from without, are linked to the compulsions arising from the physical nature of man, and from his disposition, his inherited, possibly cell-born character. The genus homo is thought to have attained human form through the working of the same factors which promoted the evolution of lower or prior organisms.

But perhaps in the case of man their relative importance may have changed. It is not maintained that evolution takes place, or has taken place, at the same rate, or at any constant rate, with all plants and animals. Certain kinds of ants, for example, appear to have remained static for millions of years. Apparently the evolution of species is no more universal or invariable throughout the organic world than progress is among the races of mankind. Some human races have never, to