Plasticity

“ If habits are due to the plasticity of materials to outward agents, we can immediately see to what outward influences, if to any, the brain-matter is plastic. Not to mechanical pressures, not to thermal changes, not to any of the forces to which all the other organs of our body are exposed; for nature has carefully shut up our brain and spinal cord in bony boxes, where no influences of this sort can get at them. ”

“ These creatures you have seen are animals carven and wrought into new shapes. To that, to the study of the plasticity of living forms, my life has been devoted. I have studied for years, gaining in knowledge as I go. I see you look horrified, and yet I am telling you nothing new. It all lay in the surface of practical anatomy years ago, but no one had the temerity to touch it. ”

“ Each relatively stable phase of equilibrium in such a structure is marked by what we may call a new set of habits. Organic matter, especially nervous tissue, seems endowed with a very extraordinary degree of plasticity of this sort; so that we may without hesitation lay down as our first proposition the following, that the phenomena of habit in living beings are due to the plasticity [2] of the organic materials of which their bodies are composed. ”

“ Rapid morphological change on the part of plastic species. When catastrophic change burst in upon the ages of uniformity, and sounded in the ear of every living thing the words 'Change, or die,' plasticity became the sole principle of salvation. ”

“ Relative plasticity.—Is there any relation between the degree of mental modifiability which remains in adult life, and the character of the mental evolution in respect of mass, complexity, and rapidity? The animal kingdom at large yields reasons for associating an inferior and more rapidly-completed mental structure, with a relatively automatic [356] nature. Lowly organized creatures, guided almost entirely by reflex actions, are in but small degrees changeable by individual experiences. ”

“ The plasticity, or educability, of the pupil is the fundamental postulate of pedagogics.
The concept plasticity, or capacity for being moulded, extends far beyond the confines of pedagogics. It takes in even the primary components of matter. It has been traced as far as the elementary substances entering into the chemical changes of organic bodies. Signs of plasticity of will are found in the souls of the higher animals. ”

“ I believe that we are subject to the law of habit in consequence of the fact that we have bodies. The plasticity of the living matter of our nervous system, in short, is the reason why we do a thing with difficulty the first time, but soon do it more and more easily, and finally, with sufficient practice, do it semi-mechanically, or with hardly any consciousness at all. ”

“ As we have seen, the acquiring of habits is due to an original plasticity of our natures: to our ability to vary responses till we find an appropriate and efficient way of acting. Routine habits, and habits that possess us instead of our possessing them, are habits which put an end to plasticity. They mark the close of power to vary. There can be no doubt of the tendency of organic plasticity, of the physiological basis, to lessen with growing years. ”

“ The evolution of intelligence as such runs parallel with the evolution of plastic behaviour; and this plasticity is necessitated by the variety and the complexity of the conditions of life—a variety and a complexity requiring many subtle modifications of response to enable the behaviour to reach accommodation to the changeful exigencies of diverse circumstances. ”

“ As life evolves, that is to say changes, by being handed on from certain forms to certain other forms, a partial rigidity marks the process together with a partial plasticity. There is a stiffening, so to speak, that keeps the life-force up to a point true to its old direction ”

“ Later, of course, when we cool off and harden and radiate into space most of our present mobility, which expresses in modesty and plasticity, we shall acknowledge no scaffoldings, gropings or tentativenesses, but think we utter absolute facts. ”

“ And, as in each individualized expression of substance there is a quality which may be termed plasticity, it follows that through inheritance and environment entities evolve in various directions, thus manifesting the scientific, the artistic and other tendencies. ”

“ The plasticity of a psychic group is due to the plasticity of the infant mind and brain, which is wonderfully capable of acquiring the language, thought forms, and differentiating characteristics of any group in which it may be reared. ”

“ Plasticity, then, is that quality which, in suddenly enforced physical change, is the key to survival and prosperity. And the survival of the plastic, that is, of the rapidly and healthily modifiable during periods when terrestrial revolution offers to species the rigorous dilemma of prodigious change or certain death, is a widely different principle from the survival of the fittest in a general biological battle during terrestrial uniformity. ”

“ As the organism ages, becomes differentiated, and adapted to special functions and conditions of life, it loses its original plasticity. The tissues become fixed and the functions set. The adult’s brain and mind begin to work in ruts. The child is superior to the adult. ”

“ The same physiologist suggests, that as there is considerable plasticity in the human frame, not only in youth and during growth, but even in the adult, we ought not always to take for granted, as some advocates of the developement theory seem to do, that each advance in psychical power depends on an improvement in bodily structure, for why may not the soul, or the higher intellectual and moral faculties, play the first instead of the second part in a progressive scheme? ”

“ Natural selection which, under a uniform and constant environment, leads to the survival of relatively fixed and definite modes of response, under an environment presenting a wider range of varying possibilities leads to the survival of plastic accommodation through intelligence. This plasticity is, however, itself hereditary. All intelligent procedure implies the inherited capacity of profiting by experience. Instinctive in the popular sense, it does not fall within the narrower definition of the term ”

“ Inanimate objects such as iron, rocks, sulphur, oxygen, etc., have no plasticity. Plants have very little possibility of forming habits. Lower animals have somewhat more, and higher animals still more, while man has the greatest possibility of forming habits. ”

“ Experimental evidence is even proving that the general plasticity of the nervous system, which has always been considered to be transitory, is of very, very much longer duration than has been supposed. ”

“ Consequently docility has been identified with imitativeness, instead of with power to re-make old habits, to re-create. Plasticity and originality have been opposed to each other. That the most precious part of plasticity consists in ability to form habits of independent judgment and of inventive initiation has been ignored. ”

“ They were his environment, these men, and they were moulding the clay of him into a more ferocious thing than had been intended by Nature. Nevertheless, Nature had given him plasticity. Where many another animal would have died or had its spirit broken, he adjusted himself and lived, and at no expense of the spirit. ”

“ Truly is it akin to human intelligence, inasmuch as it is the parent of human intelligence, the latter being the child that is developing the parental powers. This building goes on through stages on which we must not tarry, through the whole of the mineral world, gradually giving to matter the power to change shape between larger and larger limits without losing cohesion. This is what is called plasticity, the power of [144] changing shape without disintegration. Matter also gains that which science speaks of as elasticity. Now what is elasticity? ”

“ Let us suppose, however, that a group of organisms belonging to a plastic species is placed under new conditions of environment. 9. Those whose innate somatic plasticity is equal to the occasion survive. ”

“ The muscles may acquire unusual strength by use and exercise; the nerve-centres may learn certain tricks of behaviour in the course of individual life; and other structures may be similarly accommodated to the conditions which affect them. To such modifications of structure or function in the organs or parts the term acquired is primarily applied. The tissues have thus a certain amount of organic plasticity, through which they are adjusted to a range of circumstances varying in extent. They are able to acquire new modes of behaviour. ”

“ They are merely, in the most complete sense, experiments in the collective purpose, and their creator has toward them just the attitude of an anatomist toward the animals upon which he is experimenting; not indifferent to their suffering as suffering, but ignoring it in the spirit of scientific detachment necessary to subordinate means to an end. "I wanted—it was the only thing I wanted—to find out the limit of plasticity in a living form," says Dr. ”

“ This, again, is only relative, since life never wholly loses its plasticity. The bird that builds a nest, the beaver that constructs a dam, the insect that gives rise to a gall,—these, so far, mould the environment to the needs of their existence. Man in especial has the power, through his developed intelligence, of manufacturing his own environment. Here the statue is relatively rigid, and the mould plastic.
Progress may be defined as continuous adaptation. In modern phrase, this is called evolution. The continuity makes the difference between evolution and revolution. ”

“ A foundation was there­fore necessary upon which the whole superstructure of the clothing could be reared, and by which the weight might be distributed equally upon every part of the frame; and in the second place we have often to hide defects, and not unfrequently to give support in cases of spinal deformities—stooping of the body or twist of the shoulders when debility or habit have impaired the natural erect and grace­ful attitude which the perfectly-developed frame should always assume. ”

“ Moulding the supple earth with 'hand obedient to the brain,' the plasticatore has impressed his most fugitive dreams of beauty on it without effort; and what it cost him but a few fatigueless hours to fashion, the steady heat of the furnace has gifted with imperishable life. Such work, no doubt, has the defects of its qualities. ”

“ The deep-seated rhythms of growth which, as I venture to think, are the chief basis of morphological heredity, bring about similarities of form, which endure in the absence of conflicting forces; but a new system of forces, introduced by altered environment and habits, impinging on those particular parts of the fabric which lie within this particular field of force, will assuredly not be long of manifesting itself in notable and inevitable modifications of form. ”

“ Before we leave this subject of mechanical adaptation, let us dwell once more for a moment upon the con­si­de­ra­tions which arise from our conception of a field of force, or field of stress, in which tension and compression (for instance) are inevitably combined, and are met by the materials naturally fitted to resist them. It has been remarked over and over again how harmoniously the whole organism hangs together, and how throughout its fabric one part is related and fitted to another in strictly functional correlation. ”

“ As a general rule, all cramped positions that are a necessary condition of labour, if they surpass the limits of resistance and elasticity of the human frame, and especially if they operate during periods of life when the skeleton is in process of formation, result in deformities, and when the skeleton is deformed, the internal organs and hence the general functional powers of the whole organism, suffer even greater alteration. ”

“ For man has gained new muscles, in his use of the forms and forces of the inorganic world, and has commenced a new process of adaptation, which has already enabled him to extend his kingdom from the tropic to the frigid zone, and which promises to make him to some extent master of the fields of water and air. And his mental experience of wider and wider conditions of nature has produced a new form of physical adaptation—that signified in clothing and habitation. ”

“ Our systems of anatomy, and of the physiology of our mere bodily frame, would indeed have been different,—but not that more intimate physiology, which relates to the functions of the animating spirit, whose presence is life, and without which our bodily frame, in all its beautiful adaptation of parts to parts, is a machine, as inert and powerless, as the separate atoms that compose it. ”

“ The organs are elastic and they are plastic. They suffer both temporary and permanent modifications in form and function by their interaction on each other, and by the arbitrary interferences to which they are subjected by legislation or artifice of any kind. ”

“ In point of fact, nature seems to have reached the limit of her materials in creating the human species. The development of hands freed from locomotion and a brain out of proportion to bodily weight are tours de force, and, so to speak, an afterthought, which put the heaviest strain possible on the materials employed, and even diverted some organs from their original design. ”

“ I may take this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of the 'Origin of Species,' I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. ”