life proceeded, showing constantly, as it does, forms of greater complexit)' and higher adaptation? This is the phylogenetic question; and as we should expect, this is the question over which biologists have had their most earnest and lasthig controversy. This is also the only question which has interested biologists. But the second question, the ontogenetic question, is of equal importance: the question, How does the individual organism manage to adjust itself better and better to its environment } How is it that we, or the brute, or the amoeba, can leant to do anytJdngf This is the question which has interested psychologists — as far as they have shown interest at all in genetic theories.
This latter problem is the most urgent, difficult, and neglected question of the new genetic psychology. How can an organism, whether with or without consciousness, ever, under any circumstances, get a new and better- adapted function.^ This is the inquiry which I wish to take up first, describing the only view which has much currency and criticising it. For in answer to this question there is practically only one theory in the field, that of Bain, in his latest formulation of which he shows its con- formity to evolution requirements. It is based upon Mr. Spencer's earlier theory, but has certain modifications w^hich Mr. Bain states in a passage which I quote below. I shall hereafter refer to the view now described as the ' Spencer-Bain theory.'
Mr. Bain's view is this: the organism is endowed with spontaneous movement, a certain spontaneity of action which must be assumed. Certain of these spontaneous movements happen by * lucky chance ' to succeed in bring- ing the organism into some special adjustment, better 1 82 The Theory of Development.
exposure, better protection, easier function, etc.; these movements are accompanied by pleasure. The pleasure lingers in the consciousness of the creature in connec- tion with the memory of the particular movement which brought it; and the memory of the pleasure serves to incite the creature to execute the same movement again, whenever the same external conditions present themselves. The repetition thus secured serves to fix the new adjust- ment as a permanent acquisition on the part of the organism.
It is evident that on this view of adaptation, Mr. Bain assumes consciousness with pleasure and pain in the organism and also assumes an association between the sense of the pleasure and the sense or mental picture of the movement which brought the pleasure. A third sup- position should also be especially noted, — because it is usually so tacit an assumption as to go quite unremarked, — namely, that the circumstances or environment remain sufficiently constant to enable the creature to use the association between the pleasure and the movement. He must have various movements stimulated over again as before, and among them the one which before gave the pleasure, in order that the pleasant memory of this par- ticular one may be suggested along with the other possible ones. Granting these assumptions, we have a means of 'selecting' the useful movement — what I have called 'organic selection.'
The order of the 'factors of adaptation,' as we may call the elements involved in Bain's schemes, is clearly this: random movement, chance-adaptation, pleasure, memory of pleasure associated with memory of movement, adapted movement. In this order I wish to note especially the Ctcmrnt Biological Theory of Adaplaiiou. 1S3 distinction between adaptive movement, i.e., the move- ment which by chance secures the adaptation, and adapted movement, i.e., the movement which follows by association with the pleasure which is recalled in memory.
Passing now to Mr. Spencer's theory, we find a purely physiological construction.^ He supposes that originally simple contractility of protoplasm leads to a diffused con- tractile discharge throughout the mass; this results in random movements of great variety. Some of these move- ments are by chance more adaptive than others, and by this fact a larger draught of energy tends to concentrate itself upon the channels of discharge which carry out these movements. This wave of ' heightened nervous energy ' fixes an anatomical * path of least resistance,' which so comes to represent the habits and permanent adaptations of the organism.
The coincidence of these two views may be best ex- pressed in the terms of one of the authors. Mr. Bain writes: 2 "■ My leading postulates — Spontaneity, the Con- tinuing of an action that gives pleasure, and the Contiguous growth of an accidental connection — are all involved in Mr. Spencer's explanation of the development of our activ- ity...The spontaneous commencement is expressed by him as a diffused discharge of muscular energy {^Psychology ^ Vol. I., p. 544). He considers that as nervous structures become more complicated, every special muscular excite- ment is accompanied by some general muscular excitement. Along with the concentrated discharge to particular mus- cles, the ganglionic plexuses inevitably carry off a certain diffused discharge to the muscles at large; and this dif- 1 Spencer, Princ. of Psychology, I., v^§ 227 ff.
184 The Theory of Development.
fused discharge may lead to the happy movement suitable to some emergency.
'' This is the doctrine of Spontaneity in a very contracted shape; too contracted in my judgment for the requirements of the case, I have adverted to the inferiority of the dif- fused wave accompanying a central process, whether active or emotional, such as is here assumed. If another source of chance muscular movements can be assigned, and if that source presents advantages over the diffused discharge, we ought to include it in our hypothesis...Mr. Darwin expresses what is tantamount to the spontaneity of move- ment thus: * When the sensorium is strongly excited, the muscles of the body are generally thrown into violent action.' ' Involuntary and purposeless contractions of the muscles of the chest and glottis, excited in the above manner, may have first given rise to the emission of vocal sounds' {Expression, pp. ^2, 83). This is spontaneous commencement under circumstances of strong excitement; but I have endeavoured to show that excitement is unnec- essary, and that spontaneity is a fact of the ordinary working of the organs.
'* The second indispensable requisite to voluntary acqui- sition, as well as to the consolidation of instinctive powers, is some force that clenches and confirms some successful chance coincidence. Mr. Spencer's view of this operation is given thus: ' After success will immediately come pleas- urable sensations with an accompanying large draught of nervous energy towards the organs employed.' 'The lines of communication through which the diffused discharge happened in this case to pass have opened a new way to certain wide channels of escape; and consequently they have suddenly become lines through which a larger quan- Current Biological Theory of Adaptatioii. 185 tity of molecular motion is drawn, and lines which are so rendered more permeable than before.'
*' Here is assumed the Law of Pleasure and Pain. Pleasure is accompanied by heightened nervous energy, which nervous energy finds its way to the lines of commu- nication that have been opened up by the lucky coinci- dence. There is assumed as a consequence the third of the above postulates — the contiguous adhesion between the two states, the state of feeling and the appropriate muscular state. The physical expression given by Mr. Spencer to this result is, I have no doubt, correct — 'the opening up of lines of discharge that draw off large amounts of molecular motion.' " Bain's three postulates, as here summed up by himself, touch the inevitable requirements of a theory, in my opin- ion, as will be seen from the foregoing pages. For there are three requirements; first, to get movements (his ' spon- taneity,' as a substitute for Spencer's * diffused discharge' and Darwdn's * purposeless contractions'); second, to get selections made from these movements (his ' accidental success,' of certain movements); and third, 'some force that clenches and confirms some successful chance coinci- dence ' (' pleasure and pain,' identified with Spencer's *' heightened nervous energy which finds its way to the lines of communication that have been opened up by the lucky coincidence ").
But it is evident that the truth — if it be true — of ' spon- taneity ' in developed organisms does not invalidate or even supersede Spencer's 'diffused discharge'; for the phylo- genetic explanation of spontaneity — the question how did spontaneity itself arise — must rest on some such hypoth- esis as Spencer's theory of discharge, or of contractility 1 86 The Theory of Development.
in response to stimulation. So we may pass that postulate over without further question. But the second question conies: given movements — by either of these principles, both, or neither — how are some of them selected.'^ Here, again, the answer comes from both authors: by chance adaptation. Of course, we are told, some of these random movements are likely to be more adaptive than others. Suppose the creature is suffering for want of food, the movements which hit upon food are then the adaptive ones. These are then in so far selected. This we may admit as most likely. But in how far — again it is asked — is the organism able to do them a second time 1 How are these successful, good, advantageous movements kept up? * Pleasure and pain ' is at once on everybody's lips, Bain's, Spencer's, ct al. The adaptive movement gives pleasure: this secures the repetition. But, yet again, how } Evi- dently by association, we are told. The lucky movement gives pleasure; it is done again to secure the pleasure again, for of all the movements which are incipiently stim- ulated by the environment, that one which is remembered as having given pleasure, that one is done again. The movements must be incipiently stimulated, that is, the environment must be pretty constant, as was said above, for otherwise we may say: for an association one term must be given; either the pleasure to bring up the move- ment, or the movement to bring up the pleasure. We must have the presence of the movement in some kind of possibility, in order to get the sense of the pleasure to be derived from doing it. Here Mr. Spencer's theory, on the organic side, gives us an answer; and Bain, as it seems to me, adopts it as a supplement, in the quotation made above from his third edition, directly from Spencer. ** Here is Cttrrent Biological Theory of Adaptation. 187 assumed," says Bain, "the Maw of pleasure and pain.' Pleasure is accompanied by hciglitencd Jicrvous energy^ which nervous energy finds its way to the lines of communication that have been opened up by the lucky coincidence."
But now we reach a point in the development of this theory at which difficulties begin to appear. It is evident that two cases are possible in the matter of the environ- ment: the case in which the stimulus calling out the lucky movement continues to act, and the case in which this stimulus stops acting. Suppose it be light — sunlight — falling on a protozoon, and a movement results which exposes the creature better to the light, and this exposure is beneficial and pleasurable. It is clear that the sunlight may continue upon it, and so keep up its good influence; or, on the other hand, the sun may draw away and be succeeded by gloom. This theory, it is evident, makes the continuance of the adaptation dependent upon the continuance or repetition of the stimulus. What good to the organism to remember that it elongated itself by chance upward, let us say, in the light, and that this gave pleasure, if there be no longer any light in which to elongate itself upward.^ If it do it in the dark, it again exposes itself to chance; for such an elongation in the dark may be the very reaction which will destroy it. So all adaptive reactions on this theory can be adapted reac- tions— real adjustments, acquisitions — only in conditions of relative regularity and frequency of stimulation.
This theory, therefore, leaves the organism to the risk of getting repetitions of stimulus by accident; just as it got the adaptation by the chance of a lucky movement, so it can keep it only by the chance of the recurrence of 1 88 TJie Theory of Development.
the stimulus. The organism waits the second time upon chance, just as it did the first time. The postulate that pleasure from the lucky movement is the agent of adapta- tion, succeeds, therefore, only when the environing agencies of stimulation are regular and constantly available.
This necessity of regularity of conditions is put by Mr. Joseph Jastrow in these words: " The existence of habits implies an environment sufficiently constant to re- peatedly present to the organism the same or closely simi- lar conditions." ^ And writers generally assume, if they do not say, that the organism is developed by the repeti- tion of stimulations which storm it, by the laws of their own action, coming to act upon it while it remains in its place to be acted upon. Complexity of adaptation is then secured by the compounding of the reactions which are sustained in this way.^ Again, another question must be asked in regard to the postulate of ' heightened nervous energy ' which both Spencer and Bain make the physiological counterpart of pleasure. The pleasure resulting from the first acciden- tally adaptive movement, issues in a heightened nervous discharge toward the organs v/hich made the movement, a discharge which finds its way to the same channels as before, and so makes it likely that the same movement will be repeated, the external conditions remaining the same. By these discharges this movement gets, of course, a better chance of being performed on subsequent occasions. So the organism fixes its adaptations.
Let us accept this and say that something equivalent to ^Popular Science Monthly, November, 1892.
'■^ More is said of this compounding tendency, below, Chap. VIII., § 4. Cf. Spencer's exposition of it, loc. cit. Vol. I., v:i§ 231 ff.
Currcjii Biological Theory of Adaptation. 189 * heightened nervous energy ' alone can explain the repeti- tion of reactions which are both useful and pleasurable. We may call this, then, for convenience, the principle of * Motor Excess,' and say that pleasure and pain can be agents of accommodation and development only if the one, pleasure, carry with it the phenomenon of * motor excess,' and the other, pain, the reverse — probably some form of inhibition or of antagonistic contraction.
Our question then is this: What is the reason that the movements which are accidentally more adaptive than others, give pleasure? Is there anything in one move- ment, as such, more than another, that it should give pleasure } How can it matter to the protozoon, for exam- ple, whether it elongate itself upward, or flatten itself downward, that it should feel better in one case than in the other?
The only answer evidently is, that the pleasure is not in the movement in itself but in what the movement gets for the organism. The protozoon may elongate itself upward without pleasure possibly in the dark, or with positive pain. The plant may turn upward only in the light (heliotro- pism), and then downward only in the dark (geotropism), to show its adaptations. It is the sunlight which the creature gets from its elongation upward which gives the pleasure.^ Yet that the current theory, as held by psychologists, makes the first adaptive movement accidental, and the pleasure which serves as agent of accommodation to result 1 A case which fulfils the details of this illustration is to be found in certain shell-fish (muscles) which respond variably to light and shade. Some species withdraw when shadows are thrown upon them; certain others withdraw when light falls on them; and yet others respond by contraction to both light and shade. See Nagel, in Biol. Centralb., XIV., 1S94, p. 385.
190 The Theory of Development.
only from that movement, may be seen from such state- ments as the following from Hoffding, who accepts Bain's postulate of spontaneity in developed organisms. He says: " There may be accommodation even before con- sciousness by means of reflex movement. In this, move- ment is not immediately brought about by the internal state, but by a stimulus from the external world, or from a part of the organism." ^ As soon as it is criticised this bald position becomes irrational, as every one will admit: for the action of the sunlight it is which stimulates the organic and vital processes, aids nutrition, sets the organism into its life rhythms, etc. This is universally the case. It is what the organism gets by the movements which minister to its life; that is the original pleasure-giving thing, not the mere fact of one movement rather than another.
And yet, as evident as this is, I cannot find it any- where clearly brought out in the literature of this topic. It may have been taken for granted by every one, we could well believe, except that when we come to generalize this view, we find that the theory of adaptation takes on a meaning very different from that usually understood. If it is the organism's stimulations, such as food supply, contact with the oxygen of the air, equilibrium under the action of gravity, etc. — if it is such things which give the organic bases of pleasure — then these it is which serve to bring about the motor excess discharge which pro- duces the abundance and variety of movements necessary to selection. But if so again, then we do not need the first accidentally adaptive movemeftt to give pleasure, and through pleasure so to secure the excess discharge.
^ Outlines of Psychology, p. 311.
Current Biological Theory of Adaptation. 191 The old theory turns the case completely over and stands it on its head.^ We reach, in fact, from this con- sideration a new construction in which our organism begins with a susceptibility to certain organic stimulations, such as food, oxygen, etc.; these when present give pleasure, the pleasure is, physiologically considered, a heightened vitality in the central nuclear processes; this heightened, central vitality issues in a motor excess discharge; from the resulting abundant and varied movements of this excess discharge those are selected which bring more of these vital stimulations again; and these finally keep up the vitality of the organism, and by the repeated excess move- ments, provide for constantly progressive adaptations.
This position, it is plain, does not rule out the old inter- pretation entirely — the view that it is the sense of acci- dentally adapted movements which gives pleasure. For in saying that it is the stimulus or sense process which gives pleasure, according as it is vitally beneficial or not, I do not rule out any kind of stimulus or sense process. Mus- cular sensation — the sense process of accomplished move- ment— takes its place as one such process among others, and a very important one. In as far as the exercise of muscle in high organisms, or the mere fact of contrac- tility itself in the lower, is vitally good, in so far it also gives pleasure, and this pleasure serves to issue in excess discharge to the same regions again. But this is a very different view from that which says that the excess move- ments corresponding to pleasure all follow from accidental movements which are lucky.
The Spencer-Bain view seems then to say that one kind of sense process, that which reports movements, and ^ Cf. Spencer, loc. ciL, I., ]>, 545.
192 The Theory of Development.
movements only of a particular kind — those which happen to be adaptive by chance — that this one kind of sense process gives pleasure, while all others do not. But why should this be? All processes of stimulation going into the organic centres ought to follow the same law. If one kind, in as far as it serves to heighten vitality, for that reason brings up the energies of the reacting centre to the pitch of a * heightened nervous discharge,' why should not any other stimulating process which serves to heighten vitality do the same thing } And when we come to press the case more closely and ask why it is that only one class of movements — a logical class merely, those which happen to be adaptive — do in reality so act, the only practical criterion is after all, on this theory, just that which I am urging, i.e., that those movements only are adaptive which secure a new element of sense process, such as light, chemical action, food stimulus, etc., in addition to the ordinary advantage of movement itself which all move- ments, qua movements, have in common.
So far, I have spoken of pleasure, but the same holds, verbis mutatis, of pain. Let us ask this question: Where in the entire series of events constituting a reaction accom- panied by pain — stimulus, central process, movement — does the pain come in, before or after the first adapted movement, i.e., the movement that has an inhibiting influ- ence somehow upon its own further performance 1 The whole phraseology of Spencer and Bain would serve to make us think that it came in only after a movcvient so tm- hicky as to be ill-adapted, the pain being part of the effect of the movement, so that, by the memory of the pain thus got, the movement is in future inhibited. The pain got from the movement serves in memory to warn us not to Cttrrciit Biological Theory of Adapfafiou. 193 repeat tJic rdovcviejit} But here I take issue blankly, con- tending that it comes in by and in the stlninlus and before its discharge in movement, warning us not to move so as to repeat that stivnihis. It is by this ' warning,' — which is in organic terms an actual lowering of vitality and conse- quent dampening of movement, or production of contrary movements, — by this the organism tends to avoid the repetition of this stimulation.
Let us take for scrutiny the customary illustration — the one which James uses, for example, in explaining the * Meynert scheme ' of nervous action. A child thrusts his finger in a candle-flame, and is burned: he thrusts no more, but shrinks. Here the doctrine of Spencer, Bain, and many others, seems to make the function of the pain the inhibition of the thrusting movement, as itself unde- sirable. But surely the case is very different. Is this movement in itself undesirable } Is it not undesirable ojdy under these or similar circiunstances? The inhibiting effect and the pain are brought about by the burn, and the recurrence of that -— that is the thing to be pre- vented. The thrusting movement is a mere incident. Suppose the candle is brought up against the child in- stead of the reverse: it then shrinks just the same. But in this case there has been no forward movement giving a pain, by the memory of which, on the theory in ques- tion, the shrinkage or stoppage of thrusting is caused.
1 In support of this see Spencer, Prin. of Psych., Vol. I., §§ 227 f., § 232, § 237. Bain's view is seen in the quotation given above. Dr. Ward seems to be clear of this criticism, as regards the function of the pain-process, as actu- ally issuing in movements which secure pleasure or bring less pain. I can get no consistent conception, however, from Ward, since he implicates attention even when, by express claim, he is discussing ' only the original evolution.' — Eiicycl. Brit., Art. ' Psychology,' p. 73.
No doubt the child has a habit of shrinking from pain- causing things; but what I claim is just this, that it is pain-causing tilings, not painful feeling movements, which it has acquired this habit in reference to.
So far therefore, let us bear clearly in mind, our out- come is this: we accept from the Spencer-Bain theory the fact of adaptation by selection from excessive movements, and also the view that the forerunner or cause of these excessive movements is a central process which is the organic analogue of pleasure;^ but we raise an objection to that theory which seems to us insuperable: The objec- tion that it makes this pleasure, and through it all adapta- tion, result from one kind of sense-stimulus, that of the organism's own contraction, and not from others, with no ground whatever for this discrimination against the ordi- nary stimulations of the environment, such as light, heat, oxygen, food-supply, etc., which are most vitally necessary for all growth, from the first.
To obviate this objection we must hold that all stimula- tions which heighten vitality give the organic basis of pleasure and by this issue in excessive movements. This seems natural, easy, and in fact inevitable. This is what my theory does. It says: given any reason for a better central organic state of things, this better state of things shows itself, by the law of dynamogenesis, in the greater ease, facility, and variety of movements, which facilitate the adjustments and so the adaptations of the organism.
This is the first innovation which the theory which I have sketched above proposes. While securing the better basis for adaptation generally, however, it does not inter- 1 Omitting the negative or pain side, which, apart from details, proceeds in a parallel way.
C^irrcnt Biological Theory of Adaptation. 195 fere with the function of pleasure which Bain desiderates — i.e., " some force that clenches and confirms, some suc- cessful chance coincidence"^ [of movement]. For as I have said, the successful chance coincidence would still give pleasure and the same association would hold between this pleasure and the particular movement which secured it. And under regular conditions of stimulation this associa- tion would suffice to draft off the increased energy of the pleasure process into the channels of the movement which is associated with the pleasure; for the organic basis of an association must be some kind of a connective pathway between the seats of the things which are associated.