This requirement a recent theory of contractility, that of Max Verworn, seems to me, in its type^ to go far toward supplying, accordant as it is with the detailed histological results of Kiihne, Schultz, Engelmann, and others. The outcome of Verworn's work is a chemical theory of con- tractility which rests upon two known cases of chemical action. Kiihne has proved that the oxygen of the air has 1 Zeitschrift fiir ivissen. Zoologie, LIIL, suppl. Bd., p. 67. See also many of the detailed positions of Eimer's great work, Organic Evolution.
2 Quoted by Soury, Revue Philosophique, July, 1893, P- 45- ^ Die Bewegung der lebendigen Suhstanz (Jena, 1892). Verworn's work is well summarized by Soury (see last note). Cf. Burdon Sanderson's remarks on ' Chemiotaxis ' in Nature, Sept, 14, 1893, p. 471. ^ ^^X ' ^"^ ^'^ tyP^»' since the particular chemical mode of stimulation which Verworn makes exclusively the basis of life may not be, and probably is not, the only kind of stimulus to which the organism effects the same typical kind of circular reaction.
272 Organic Imitation.
chemical affinity for the outer layer of particles of a proto- plasmic mass. The elements set free by this union find themselves impelled toward the centre by their affinity for the nuclear elements. This new synthesis releases elements which again move outward toward the oxygen at the sur- face.^ Thus there are two contrary movements: away from the nucleus, or expansion, and toward the nucleus, or con- traction. Considering the oxygen action as stimulus, we have thus a reaction which keeps up the action of its own stimulus, and thus perpetuates itself, giving just the type of reaction which my theory, outlined above, calls ' imita- tion.' Verworn pushes the claim of this type of vital action right up through all the forms of muscular action — just as Eimer finds only the one type of function necessary, with repetition, to account for all the morphological varia- tions. I am certainly, therefore, in touch with biological authorities in claiming that this type of reaction is essential to neurological development; and especially so when we come to see, in what follows, that the progress of con- sciousness can be accounted for in stages corresponding, in its great features, with the stages of differentiation required by the physiological and anatomical theories.
Further, recent researches on the behaviour of unicellu- lar organisms and of plants show the same kind of so-called selective or * nervous property,' with antithetic adaptations of attraction and repulsion. These creatures develop not by remaining still and awaiting the accidental repetition of stimulations by storming or assault. On the contrary, they do exactly what we have long thought it the exclusive right of higher conscious creatures to do; they go after, 1 The exhaustion of the nucleus by stimulation is shown by the work of Hodge, Changes due to Functional Activity of N'ef-ve Cells (Boston, 1893).
The Neurological Qjiestion, 273 or shrink from, a stimulating influence, according as its former impression has been beneficial or damaging. In other words, they perform reactions of the stimulus- maintaining, or imitative, type. Binct ^ draws the conclusion that protozoa have memory, choice, volition; that is, as I should prefer to say, they behave as though they had. Bunge, in his lectures on physiological chemistry, after describing the actions of certain ' apparently quite struc- tureless ' creatures, Vainpyrella and Colpodcila, says: " The behaviour of these monads in their search after food, and their method of absorbing it, is so remarkable, that one can hardly avoid the conclusion that the acts are those of conscious beings." " Later on," says a writer in the British Medical Journal^ *' he gives the still more remarkable case of the orcellae. Whenever an attempt is made to place them in an inconvenient position, they are always able by the development of gas bubbles of appropriate size and at the proper spot, to right themselves...etc. ' It cannot be denied,' says Engelmann, 'that these facts point to psychi- cal processes in the protoplasm.' " Late researches show- ing the effect of lights of different colours upon these elementary creatures, is also in evidence. They swarm into certain lights and avoid others. Certain bacteria distinguish the trillionth part of a milligramme of certain substances in solution — showing lively attraction — quan- tities which the tests of chemical reaction and the finest chemical balances fail to detect. If extract of meat be ex- posed near these creatures, which feed on it, they swarm toward it from afar, crawling over one another. But just as soon as a little poisonous extract, in the most minute ^ Psychic Life of Micro-o7'ganisms.
quantity conceivable, be added, the bacteria fly from the mouth of the tubes in haste, with all the external signs of intelligence and fear.
In regard to plants, the recent evidence of their active responses to stimulations of all kinds by extension and retraction is simply remarkable. Pfeffer has shown the conditions of the perpetual movements known as geotro- pism, hydrotropism, heliotropism in plants. The fact of twining movement in the tendrils of various plants has been subjected by this investigator to delicate tests. He finds that the tendrils of the pea will twine about a thread of silk which exerts a pressure of only the ioo,oooth part of a milligramme, while the force of the wind and the rain or the constant pressure of a stream of mercury, have no effect whatever. The tendrils distinguish between liquid and solid touches. A wound upon a plant is a signal for a movement of protoplasm throughout the entire plant, and a migration toward the damaged part. ''It is," says Pfeffer, ''just as if the plant had the power of moving itself. Its sensibility is developed to the highest degree, and it reacts to light, heat, contact, electricity, and chemi- cal influences." ^ The researches of Hegler show that if a weight be attached to a growth stem of a plant, greater mechanical strength is developed in the stem to withstand the weight, a fact analogous to the fact shown by Waller that an isolated muscle is able to do more work when a greater demand is made upon it in the way of resist- ance.^ Growing roots show enormously increased growth 1 Pfeffer's 'Address at the first general meeting of the Society of German Naturalists and Physicians,' at Nuremberg. See Revue Scientifique, Dec. 9, The Neurological Questioji. 275 power when resistances are put in their way. The fruit buds of certain plants resist the action of gravity, growing upward, as long as the germinal vescicles are uninjured. All the other parts of the buds and flower may be cut away, but it still grows serenely up. But only let the germinal vescicles be removed — parts which in size and weight are infinitesimally smaller than these others, and the whole bough sinks toward the earth.
The theory adopted by the great botanist mentioned, Pfeffer, in explaining these phenomena, falls in so easily, up to a certain point, with those of Eimer and Verworn al- ready described, that it even suggests the via media which is required by the doctrine of accommodation through the law of * excess ' expounded in the foregoing pages. Says Pfef- fer: " Having a view to all the particulars in the process of reaction and its effects, we find that the essential principle of all these phenomena is to be looked for in the produc- tion of a central orgaiiic response (^Ansldsnng, detente, release, or * trigger-action '). This is the only definition which covers all the phenomena...And it clearly results from it that irritability is never simply the result of the stimuli which bring out the reaction; these only serve to discover the prop- erties and the specific agencies of the organism itself, and that the whole proceeding is due to the peculiar energy of the organism...A simple mechanical action, for example, which represents an equivalent transformation of energy, does not constitute an irritation, although in the chain of phenomena due to irritability, there is more than one such transformation; for there is never irritation without an external or internal stimulant which sets in play the poten- tial energy of the plant. Here we are dealing with phe- nomena of another order than those of a membrane drawing in water by stretching, or of a cell filling itself by osmose, or finally of a branch bending under a weight." Further, in certain kinds of reaction, such as heliotropism, etc., Pfeffer points out the ability of the organism to 'release' its energies again and again to the same stimulus, and so to keep its processes a-going: *' However little the ensemble of effects follow the release automatically, never- theless the organism may prolong a reaction once provoked, or, after reacting, re-establisJi the state favourable to the re- actioiiy^ Uniform conditions, also, such as air, tempera- ture, etc., he holds to be constant stimulation by which the organism is kept in a state of static or recurrent contrac- tion. Plants continue to grow in forced directions some time after being again set free. " If the temperature re- mains constant, the plant finds itself in a state of static irritation — a condition necessary to vital activity. It is in this sense that certain permanent influences are general and absolute conditions of the functioning of the organ- ism." 2 This, it is clear, is in full accord with the theory of Verworn and with the oxygen discovery of Engelmann, and recognizes the ability of the lowest organisms to pro- duce already reactions of the circular or imitative type.
The general theory of Ausldsnng, or 'trigger-action,' stated by Pfeffer, is as old, he says, as his work on Phys- iology (1881), and his Osinotische UntersiicJuinge^i (1877), and he also traces it to Dutrochet (1832). This is inter- esting, I think, on account of its close approach to the heightened nervous energy of Spencer, which also turns upon a storing up of potential energy. Yet I am not able to discover that Pfeffer uses this ' excess ' storage for pur- 1 Revue Sciejitifique, loc. cit., p. 741. Italics mine.
2 Pfeffer, loc. cit.
The Neurological Ques/ion. 277 poses of the further rtdaptation of the organism: a Umita- tion of view which could not well be avoided in observing the actions of plants alone, which do not, as animals do, learn new adapted movements before our very eyes. He seems simply to recognize it as there, to account for reac- tions actually observed.
Of course this class of facts, w^hich show the same kind of selective reaction in lower organisms as in the higher, where consciousness is present,^ may be used to support a certain dualism of chemistry and life. This is done among some later biologists, the so-called * new vitalists '; but psychologists are becoming so familiar with the prob- lems which demand a reconciliation of form and content, and so willing, for purposes of science, to state everything in terms of content, that this need not trouble them much. It is well to recognize, however, that if organic and mental accommodation are, as I am endeavouring to prove, one and the same thing, then the psychologist may have more right than is customarily given him of solving the dualism in this particular case by interpreting even the affinities of chemistry after analogy with the selective function of con- sciousness.
The bearing of the present condition of neurological research is now sufficiently evident from the evidence cited. Whatever else it shows, this is clear, that wherever there is life there is irritability, nerv^ous property. Further, wherever there is life there is the spontaneous selection of stimuli and the motor adaptations necessary to it.
1 See an interesting collection of additional facts showing the * nervous property ' in low organisms, in Orr, Theory of Development aiid Heredity, Chap. IV. The authors cited are so easily accessible that I do not quote fur- ther from very many available instances.
278 Organic Imitation.
Wherever there is Ufe there is means of continuing advan- tageous stimulations by drawing up to them by active move- ment, or by other actions whose evident purpose is the same. Such a property could only have arisen by the natural selection of the organisms which were endowed by varia- tion or otherwise (or by its abrupt appearance with life itself), with a central physiological process of a kind by which the contracting energies of the organism were directed into certain favourable pathways and withheld from other pathways. This is the principle of ' motor excess ' as worked out above.
All this is equally true of the reactions which are con- sciously selective or inhibitory; the two great agents of such selection being attention, and pleasure and pain. I accordingly claim that the evidence of biology is in favour of the conclusion that the phenomena of ' excess ' in unicellular creatures are, in some way, the nervous analogues to these conscious functions. How they are involved in pleasure and pain states of consciousness has already been touched upon in part. The theory of the rise of attention is to follow below.
Again, the adaptation of all organisms is secured by their tendency to act so as to reproduce or maintain stimulations which are beneficial. In this way only can new reactions be made available for repetition, and so secured to habit. But this reaction, which tends to secure a continuation of its own stimulation, is exactly the nervous process of conscious imitation. Hence we may say that all organic adaptation in a changing environment is a phe- nomenon of biological or- organic imitation} ^ The use of the word ' Imitation ' in this wide sense has been justly criti- cised; but I am at a loss to suggest a better term. Besides, it is the essence Physical Basis of Memory and Association. 279 § 3. The Physical Basis of Memory and Association.
In the nervous processes so far sketched we have, I think, the adequate basis of the development of an organ- ism up to a certain point. It is evident that, in it all, the organism is directly dependent upon the actual stimulating agencies of nature. Sensations, perceptions, objects, are necessary to call out the reactions characteristic of it. And who would expect that the organism could in any way escape this dependence } Yet we have already found, in the fact of pleasure and pain reactions, that the organ- ism takes active attitudes toward the sources of stimulation and thus in a measure turns the events of its environment to better account. But this is only the start: the marvels of development are not yet well begun!
Is the occurrence of any reaction, we may ask, possi- ble in the absence of the external stimulus which is suited of my contention that the method of organic adaptation is by reactions of this identical type with further repetitions of them. The term ' adaptation ' is too general. ' Repetition,' the word used by the biologists, is too narrow, since it is only repetitions brought about in part by the organism itself which I have in mind, not all repetitions, as the old biological theory of adaptation is accustomed to hold. One of my correspondents — and so also a critic in the Academy — thinks Habit covers it; but it is just my point that it does not cover it. I am asking just how habit could ever have started in an organism — apart from fortuitous lucky chances. Of course this method of adaptation itself becomes a habit: the fact of imitation by children show it. But the main function of the thing even then is that of breaking off habits by the new actions which the child learns through its imitations. If any one will suggest a more happy term for the reaction which is at once a new adaptation to any sort of stimulation and the beginning of a habit or tendency to get that sort of stimulation again, I shall hail it gladly. In the meantime I use the word which expresses the type to which the reaction undoubtedly belongs, even at the risk of being charged with a desire to psychologize the facts of biology; but I do not wish, of course, to prejudice the argument by a word ill-used.
28o Ororanic Imitation.
^> to start it? Evidently it is not possible, unless there be some way whereby the energies of the reaction in question may be started by something equivalent to the working of the original external stimulus.
We have seen how it is that the organism goes out to find its stimulus by a kind of imitation; we now find the still more remarkable fact for which this is only the prepa- ration — but the necessary preparation — the fact of mem- ory. Memory is, as everybody says, on the bodily side, the reinstatement in the nervous centres of the processes con- cerned in the original perception, sensation, etc.; this much at least, whatever else it may involve. These processes, of course, tend always, when started, to issue in movement, just the same, no matter how they themselves are started. So the function of the reinstatement ^of processes in the act of memory is, in respect to the tendency to action which these processes arouse, exactly the same as that of the processes of perception, sensation, event, which furnished the original of the memory.
But in memory the object or thing remembered itself is absent; yet inasmuch as its proper reaction in move- ment comes about just the same, we have a new stage in what is still our old friend the ' circular,' the * stimulus- retaining ' reaction. It gets started from the brain centres to be sure, but it aims, just the same, to bring about the consequences which it did when it was directly started by the sense-stimulation. It aims, that is, to bring the organ- ism into touch with the stimulation itself again if it be a desirable one, or, in contrary cases, to get the organism away from the stimulation.
This is accomplished in the organism by an arrange- ment whereby a group of processes, corresponding to what Physical Basis of Memory and Association. 281 we call in consciousness ' copies for imitation,' some of them external as things, some internal as memories, con- spire, so to speak, to ' ring up ' one another. When an external stimulus starts one of them, that starts up others in the centres, and all the reactions which wait upon these several processes tend to realize themselves. So, many reactions which, but for this, would never get stimulated except when the actual material stimulus is there, are started by and with others whose stimuli are there. And with the multiplying of these secondary or remote ways of stimulation, the more and more varied and complex habits of the organism come to be less and less dependent upon the particular external events of the world, and more capable of remote stimulation through senses which origi- nally did not constitute their stimulus, but which by this organic 'conspiracy,' called — I may as well anticipate — association, come to do so; while the increasing variety of the conspiring elements — constantly recruited from the new experiences of the world and all represented by cer- tain nervous processes — make up a large and ever larger mass of connected centres, which vibrate in delicate coun- terpoise together.
The arrangement thus sketched, therefore, is the physi- cal basis of memory. A memory is a copy for imitation taken over from the world into consciousness. Memory is a device to nullify distance in space and time. It remedies lack of immediate connection with the come-and-go occur- rences of the world and makes the organism to a degree independent of them. Every act I set myself to do is either to imitate something which I find now before me, or to reproduce, by my own action, something whose ele- ments I remember — something whose copy I get set within me by a * ring up ' from elements which are events or objects in the world now before me.
The neurological theory so far advanced, with too great brevity, is along the lines first announced, possibly, by Tarde.^ Tarde's theory, which I find obscure, is improved in quotation, and endorsed by Sighele.^ It may be analyzed into two factors, i.e., {a) the securing of repetitions by imita- tion, a speculative idea based upon the mere fact that ani- mals and man do consciously imitate; and {U) the theory of memory, considered as a means of perpetuating and com- plicating the effects of repetition in mental development. This latter factor I find only vaguely and inadequately stated by Tarde. It is readily seen that his view, also, assumes the fact of conscious or semi-conscious imitation, makes of it an original endowment or kind of social in- stinct, and is, in so far, open to the objections which may be urged^ against such a position from the point of view of development; for one of the great problems of the theory of development is to account for instincts of all kinds. And, moreover, of all instincts the social are pos- sibly the most complex and the latest. They involve a great measure of the individual organic and mental attain- ment found in memory, imagination, emotion, etc.
The theory which I am now proposing, on the other hand, supplies this lack. It gives a derivation of imitation based upon an analysis of the imitative reaction itself. This analysis — the outcome of which I have expressed by calling imitation a ' circular reaction,' i.e., one which tends '^ Les Lois de P Imitation, Chap. III.; published earlier in an article "Qu'est-ce qu'une Societe," Revue Philosophiqiie, XVIIL, 1884, p. 489. - La fotile criniinelle, pp. 42 ff. ^ Cf. Bain, Senses and Intellect, 3d ed., pp. 413 ff., mentioned again below.
Physical Basis of Mcniory and Association. 283 to keep up its own stimulating process — gives us a means of defining imitation and fixing the limits of the concept.^ The third and fundamental factor, therefore, which the development stated above, compared with the earlier theories, endeavours to supply, is the theory of the rise of imitation itself from the simple vital processes of an or- ganism through the occurrence, among ' spontaneous life variations ' of creatures whose vital discharges are move- ments of the ' circular ' type, which tend directly to secure the repetition or maintenance of certain good stimuli. And, in like manner, the suppression of reactions which are damaging or useless follows, for by that very fact they lower the vitality of the organism and so hinder their own recurrence. This derivation of imitation secured, we are able to develop independently the two principles urged by Tarde and Sighele, on both sides, the bodily and the mental.
We reach now a new stage in race history. As habit goes on forming, accommodation enters in a new form. New reactions which prove to be beneficial, have them- selves to become matters of habit, have to be accommo- dated to by the organism as a whole, have to be taken up into the network of conspiring processes which represent the sum of adaptations to date. Here it is that the prin- ciple of association largely gets its astonishing value in nervous and mental development.
We have found reason to think that mere repetition with association would not suffice for development, and that the principle of * organic imitation ' must be added, for the 1 Cf. Tonnies' remarks on Tarde's book in Philos. Monatshcfte, 1893, P- 298, showing the need of more definition in this wliole field.
reason that association alone would simply render habits more compact. This is true also in higher development after the process of memory comes; yet here association has much wider application. For example, a child does not learn to speak by merely getting his accidental vocal muscular sensations associated with the significant sounds which he makes, though I know that that is a wide-spread view. For at that rate of learning the number of words in his vocabulary would be less than the number of days in his life. On the contrary, he yields to his tendency to imitate all sounds, and by strenuous effort succeeds, thus getting a great number of significant sounds and their necessary muscular sensations. This, now, becomes asso- ciation's opportunity to show the manner of its action — a chance it could not have had otherwise. And it does.
Nervous association does two things. First, it does here what it has been seen to do in the lower organisms: it binds sense of stimulus and sense of movement together. The child who has learned to make a sound, then makes it by association whenever he hears it. But second, associa- tion does more, — and here comes in the tremendous influence of the fact which I have been describing by the phrase 'central conspiracy,' — association brings differ- ent reactions together as wholes; it links together the elements of copy at the centre, so that a stimulus may produce, not only its own associated reaction, but, by its association with another stimulus, or with the vicniory of that other, it may suffice to produce the reaction associated with the second stimulus, or a third, fourth, etc. This we have already seen in the fact of * substitution ' in the mat- ter of emotional attitudes.^ 1 Above, Chap. VIII., § 4.
Physical Basis of Mcuiory and Associafioji. 2S5