§ 190. By this law, if it is the true one, must be interpret- able all the phenomena, from their lowest to their highest grades. Let us first observe how far the leading deductions agree with the leading facts.
A manifest corollary from the law is that the psychical relations in any organism, will correspond besu to those physical relations it comes most in contact with. The environment in general is infinite. The environment of each order of creature is practically more or less limited. And each order of creature has an environment which, besides being limited, is practically more or less special. The law implies, then, that the psychical relations displayed ' by each order of creature, will be those which recur the. oftenest within the range of its experience. And we know^ the fact to be that they are so.
Contemplating the animal kingdom at large, the first psy- chical relations established ought to be those answering to the most prevalent environing relations of the simplest kind. Such are just what we find. The stationary polype with out- stretched tentacles, contracts on being touched. Now a creature that is not itself moving can be touched only by something in motion. Ami, this universal relation between collision and some moving body, is one of the first to be re- sponded to. When a shadow passing across a rudimentary eye is followed by a movement in the creature possessing that eye, the internal relation between the impression and the motion corresponds with the relation between a passing opacity and a passing solidity in the environment; and this is one of the most general relations. Various analogous cases will suggest themselves.
426 SPECIAL SYNTHESIS.
In the progress of life at large, as in the progress of the individual, the adjustment of inner tendencies to outer per- sistences, must begin with the simple and advance to the complex; seeing that both within and without, complex re- lations, being made up of simple ones, cannot be established before simple ones have been established. After experience of some persistent relation A to B in the environment, has generated a persistent relation between the answering psy- chical states a and 5; and after some other persistent outer relation C to D, has similarly generated a persistent inner relation c to d; then, if in the environment there exists any relation between the relations A to B and C to D, it becomes possible for repeated experiences to generate in the organism a relation between a to I and c to d. But it is manifestly impossible for this to be done until the relations a to & and c to d have been themselves generated. This deduction, too, we see to be in complete conformity with the facts, both ol individual evolution and of general evolution.
Further, it must follow that the only thing required for the establishment of a new internal relation answering to a new external one, is, that the organism shall be sufficiently developed to cognize the two terms of the new relation, and that being thus developed, it shall be placed in circumstances which present the new relation. Here also, there is har- mony between the a priori inference and the inference from observation. In our domestic animals there are constantly formed new psychical relations answering to such new phy- sical relations as have terms sufficiently simple to be per- ceived. And in human civilization we see the truth illustrated in the progress to wider and wider general- izations.
But the validity of these several corollaries will become more^apparent as we proceed. Let us now pass on to contie...growth of Inteliience' under its "leading CHAPTER IV.
REFLEX ACTION.
§ 191. Under its simplest form, Eeflex Action is tbe sequence of a single contraction upon a single irritation. A vague manifestation of this seqnence marks the dawn of sensitive life; and, indeed, it is chiefly because they shrink on being touched, that many of the simpler animals are recognized as living.
But though in the movements of Zoophytes it is fore- shadowed, Heflex action proper is exhibited only when we ascend to creatures in which there exist nerves and muscles. In such creatures, the response is effected not through the agency of the one uniform tissue consti- tuting the body, which is at once irritable and contractile; but the irritability is confined to one specialized struc- ture, while the contractility is confined to another special- ized structure; and the two structures are placed in such relation that irritation of the one is followed by contraction of the other. Some impression is made on the peripheral termination of a nerve; the molecular motion it sets up is propagated along the nerve until it reaches a ganglion; the large quantity of molecular motion there disengaged, dis- charges itself along another nerve proceeding from the ganglion to a muscle; and thus the stimulus carried through an afferent nerve to some libero-motor centre, is thence reflected in multiplied amount through an efferent nerve to che contractile agent.
428 SPECIAL SYNTHESIS.
In this simplest form of psychical action we see a single internal relation adjusted to a single external relation. Any one of the suckers on the arm of a cuttle-fish that has been separated from the body, will, under the influence of its own independent ganglion,, attach itself to a substance placed in contact with it — the established relation between the tactual and muscular changes in the sucker and its ganglion, is parallel to the uniform relation between resist- ance and extension in its environment — the inner cohesion of psychical states is as persistent as is the outer relation between attributes. And if we remember that in the actions of the cuttle-fish this inner relation is perpetually being repeated in response to the outer relation, we see how the organization of it in the species answers to the infinitude of experiences received by the species.
§ 192. Reflex action being the lowest form of psychical life, is, by implication., most nearly related to physical life: in it we see the incipient differentiation of the two. This truth may be discerned from several points of view.
It was shown that the contraction which occurs in a polype when touched, or otherwise stimulated, probably results from the increased vital change which the stimulus produces in the disturbed' tissues (§ 140); and though one of these reflex actions, as of a cephalopod's sucker,, is effected in a more definite and more complicated way, yet it does not so far differ as to be removable from the class of phy- sical actions. Mostly, it would be considered as a misuse of words to call it psychical. So that while as belonging to the order of vital changes which, in their higher complications, we dignify as psychical, it may be convenient to classify it as psychical; yet it must be admitted that in position it is transitional. Again, in well-organized creatures, the physical life is itself regulated by reflex actions. Those rhythmical movements of the alimentary canal which follow the introduction of food, are of reflex origin; as are also KEFLEX ACTION. 429 those processes by which, under the same stimulus, the digestive fluids are prepared and poured out. The various viscera, too, performing each its separate function, must have their relative activities adjusted; and the due bal- ancing of them is effected by reflex action. It is held that the changes in the state of each viscus are impressed on the nerves proceeding to ganglia in the sympathetic, whence they are reflected to the other viscera; so that, for instance, when the stomach has been filled, the stimulus it diffuses through this channel to the heart and lungs, causes them to send it an increased quantity of aerated blood. In yet another respect may we see a close alliance between the physical life and this nascent psychical life. As was shown in a foregoing chapter, the psychical life is broadly distin- guished from the physical life by the peculiarity that its changes, instead of being simultaneous and successive, are successive only; but, as was also shown, this peculiarity makes its appearance gradually, and becomes marked only when the psychical life becomes high. Now the reflex actions in which the nascent psychical life is seen, are nearly as much characterized by simultaneity as are the purely physical actions. A great number of these simplest nervous changes go on quite independently in the same organism at the same moment. Once more, the proximity of these reflex actions to the physical life is im- plied by their unconsciousness. Not only in co-ordinating the visceral processes, but also in co-ordinating the pro- cesses of perception, there constantly go on reflex actions of which we have no immediate knowledge; as those by which the focus of each eye is adjusted to distances and the closure of the iris adapted to the quantity of light. Other, reflex actions of which we can take direct cognizance — as that of breathing — can go on without our thinking of th$m. And others which are commonly accompanied by local sen- sation— as when the foot is withdrawn from something which tickles it — are found to be most energetically per- 4-30 SPECIAL SYNTHESIS.
formed when, from some spinal lesion, local sensation has been abolished. Eemembering how nearly unconscious our own locomotive actions become when we are absorbed in thought,, it is inferable that in creatures whose reflex loco- motive actions are congenitally perfect, they are quite un- i conscious. The rapid alternations of a centipede's leg or a fly's wing, are probably as automatic as are those of a steam-engine piston; and may be co-ordinated after a gene- rally analogous manner. Just as, in a steam-engine, the arrival of the piston at a certain point is necessarily accom- panied by the opening of a valve serving to admit the steam which will drive the piston in the reverse direction; so, in one of these rhythmically-moving organs, the performance of each motion ends in bringing the organ to a position in which the stimulus to an opposite motion acts upon it.
But though, from all points of view, Reflex action is seen to be a species of change very little removed from the ,. physicaf changes constituting vegetative life; yet even in it we may 'discern a fulfilment of the primordial conditions to consciousness. In the lowest conceivable type of con- 1 ^sciousness — that produced by the alternation of two states — 'there are involved the relations constituting the forms of all thought. And such an alternation of two states is just that which occurs in the ganglion connected with one of these rhythmically-moving organs.
§ 193. From that lowest kind of Eeflex action in which a single impression produces a single contraction, the ascent is to complications in the stimuli and in the acts resulting > from them. There is no precise distinction between a single i contraction and a combination of contractions. From the •|! excitation of dispersed muscular fibres to the excitation of fibres aggregated into definite bundles, the transition is insensible; and there is similarly a gradual passage from , single contractions to combinations of contractions. Hence, .under the head of Eeflex action there are classed numerous REFLEX ACTION. 431 cases in wHcli a wliole group of muscular motions results from one impression. The decapitated frog which leaps when one of its feet is irritated, supplies an illustration. To examine the varieties and complexities of Reflex action, is ' the task of the physiologist rather than of the psychologist. Here it concerns us merely to note the bearing of the phe- nomena on the general argument.
We have to observe that these simplest of psychical changes correspond to external relations which are only one degree more specialized than the relations to which physical changes correspond. While the processes of the purely vegetative life are in adjustment with those most general relations between nutriment, oxygen, temperature, 'moisture, light, which pervade the environment at large; these lowest processes of the animal life are in adjustment with the most general relations of the solid bodies con- tained in the environment: as those between tangibility and solidity, motion and life, Further, it is to be noticed that in conformity with the s general law of intelligence, we have, in one of these reflex actions, an established connexion between two psychical j states answering to an established connexion between two I external phenomena. Not that the inner tendency is exactly proportioned to the outer persistency. In many cases it is absolute in the organism though by no means absolute in the environment. And this is just what is to be looked for among these manifestations of nascent in- telligence; since the adjustment of the inner tendencies to the outer persistencies, being the law of intelligence in the abstract, cannot be fulfilled where the intelligence is in- cipient.
Lastly may be named the fact, that these iiidissolubly- connected psychical states exist where there are perpetftally- repeated experiences of the external relations to which they answer.
CHAPTER T.
INSTINCT.
§ 194. Not using the word as the vulgar do, to designate all other kinds of intelligence than the human, but restrict- ing it to its proper signification, ibstmotjaaaj be described as^^componnd reflex action. I say described rather then define37~*^ line of demarkation can be drawn between it and simple reflex action. As remarked in the last section, the dirigo-motor processes which reflex actions show us, pass by degrees from the simple to the complex; and a cursory inspection of the facts shows us that the recipio-motor processes do the like. Nevertheless we may conveniently distinguish, as a higher order of these auto- matic nervous adjustments, those in which complex stimuli produce complex movements.
That the propriety of thus marking off Instinct from primitive reflex action may be clearly seen, let us take examples. A cl^d^ immediately it comes out of the egg, not only balancesrtself and runs about, but picks up frag- ments of food; thus showing us that it can adjust its muscular movements in a way appropriate for grasping an object in a position that is accurately perceived. Ob- vioi^ly this action, which is proved by the circumstances fco be purely automatic, implies the combination of many stimuli. The excitation of certain retinal nerve-fibres must be one — an excitation which is itself a somewhat special INSTINCT.
INSTINCT.
combination of excitations. Another component in the gene- ral stimulus must be that proceeding from the muscles by which the eyes are directed. And yet another component must be that proceeding from the muscles which alter the focal adjustments of the eyes. Without impressions pro- ceeding from both these sets of muscles, it would be im- possible for the head to be guided in the right direction, or for the beak to be closed at the right moment. Thus the action implies impressions on retinal nerves, impressions on nerves proceeding from muscles which move the eyes, and impressions on nerves proceeding from muscles which adjust their lenses — implies that all these nerves are excited simultaneously in special ways and degrees; and that the complex co-ordination of muscular contractions by which the fly is caught, is the result of this complex co-ordination of stimuli. Of such co-ordinated acts automati-" cally resulting from co-ordinated stimuli, we have many illustrations in ourselves. Though originating in volition; our ordinary movements are performed in a mode just like that described. When putting out the hand to grasp an object before us, we are unconscious of the particular muscular adjustments made. We see the object, and in response to the wish for it the arm is moved in a fiu way. But were any of the various nervous stimuli in- volved in the perception absent, the arm would not be guided aright. That is to say, the special muscular co-or- dination is due to the special co-ordination of sensations received from the eye and its adjuncts: volition being con- cerned merely in setting the process going. One of these actions of our own differs from that of the newly-hatched fly- catcher mainly in this, that whereas, in ourselves, the impressions and motions, being almost infinitely varied and severally repeated with comparative infrequency, are not congenitally co-ordinated but are co-ordinated in the course of our first years; in the fly-catcher, descended from a race in which a special combination is perpetually repeated by SPECIAL SYNTHESIS.
every individual throughout life, this combination is ready- organized.
So that while in the primitive forms of reflex action a single impression is followed by a single contraction; while in the more developed forms of reflex action a single im- pression is followed by a combination of contractions; in this which we distinguish as Instinct, a combination of im- pressions is followed by a combination of contractions; and the higher the Instinct the more complex are both the directive and executive co-ordinations. Carrying with us this conception, let us now contemplate the facts in con- nexion with the general laws we are tracing out.
§ 195. Instinct is obviously further removed from purely physical life than is simple reflex action. While simple reflex action is common to the internal visceral processes and to the processes of external adjustment, Instinct is not. I There are no instincts displayed by the kidneys, the lungs, f the liver: they occur only among the actions of that nervo- J muscular apparatus which is the agent of psychical life. ^ Again, the co-ordination of many stimuli into one sti- mulus is, so far as it goes, a reduction of diffused simul- taneous changes into concentrated serial changes. Whether the combined nervous acts which take place when the fly- I catcher seizes an insect, are regarded as a series passing £, through its centre of co-ordination in rapid succession, or as ^ consolidated into two successive states of its centre of co- | ordination, it is equally clear that the changes going on in 1 its centre of co-ordination have a much more decided linear./ arrangement than have the changes going on in the scattered ganglia of a centipede.
In its higher forms, Instinct is probably accompanied by "a rudimentary consciousness. There cannot be co-ordination of many stimuli without some ganglion through which they are all brought into relation. In the process of bringing .them into relation, this ganglion must be subject to the INSTINCT, 435 influence of each — must undergo many changes. And the quick succession of changes in a ganglion, implying as it does perpetual experiences of differences and likenesses, constitutes the raw material of consciousness. The implica^ tion is that as fast as Instinct is developed, some kind of consciousness becomes nascent.
Further, the instinctive actions are more removed from the actions of simple bodily life in this, that they answer to external phenomena which are more complex: and more special. While the purely physical processes going on throughout the organism respond to those most general relations common to the environment as a whole; while tne simple reflex actions respond to some of the general relations common to the individual objects it contains; these com- pound reflex actions which we class as instincts, respond to those more involved relations which, characterize certain orders of objects and actions as distinguished from others.
Greater differentiation of the psychical life from the phy- sical life is thus shown in several ways — in the growing distinction between the action of the vegetative and animal systems; in the increasing seriality of the changes in the animal system; in the consequent rise of incipient; con- sciousness; and in the higher speciality of the outer relations to which inner relations are adjusted: which last is indeed the essence of the advance, to which the others are necessary accompaniments.
§ 196. We are now prepared to inquire how, by_ac- I cumulated experiences, compound reflex actions may be \ developed out of simple ones.
Let us begin with some low aguatic creature possessing rudimentary eyes. Sensitive as such eyes are only to marked changes in the quantity of light, they can be affected by opaque bodies moving in the surrounding water, only when such bodies approach close to them. But bodies carried by their motion very near to the organism, will, by 4-36 SPECIAL SYNTHESIS, their furtber motion, be brought in contact with it. The cases in which an external object passes by almost at a tan- gent to that part of the organism where the rudimentary eye is placed; so as nearly to touch the surface but not quite, must be exceptional. In its earliest forms sight is, as before said, little n>ore than anticipatory touch (§ 142): visual impressions are habitually followed by tactual ones. But tactual impressions are,, in all these creatures, habitually followed by contractions — contractions which, as was pointed out in § 140, are probably the necessary effects of mechanically accelerating the vital changes — contractions which, under like stimuli, occur even in certain plants, and are so shown to be producible by alterations in the processes of purely physical life. Eesult as they may, however, it is beyond question that from the zoophytes upwards, touch and contraction form an habitual sequence; and hence, in creatures whose incipient vision amounts to little more than anticipatory touch, there constantly occurs the succession — a visual impression, a tactual impression, a contrac- tion. 4 Now the evolution of a nervous system is a necessary concomitant of that specialization which originates the senses. On the one hand, until the general sensitiveness is in some degree localized, the intermincial function of the nervous system cannot exist; and on the other hand, no such localized sensitiveness can exist without something in the shape of nerves. A nascent sense of sight, therefore, implies a nascent nervous communication. And along with a nas- cent nervous communication we may see the first illustration of the growth of intelligence. If psychical states (using the term in its widest sense) which follow one another time after time in a certain order, become every time more closely connected in this order, so as eventually to become insepar- able; then it must happen that if, in the experience of any species, a visual impression, a tactual impression, and a con- traction., are continually repeated in this succession, the several nervous states produced will become so consolidated INSTINCT. 437 that the first cannot be caused without tlie others following — the visual impression will be instantly succeeded by a nervous excitation like that which a tactual impression pro- duces, and this will be instantly succeeded by a contraction. There will thus occur a contraction in anticipation of touch. What must result from a further development of vision? Evidently the same bodies will be discerned at greater distances, and smaller bodies will be discerned when close;f to. Both of these must produce obscurations which are faint in comparison with that obscuration produced by a large body about to strike the creature's surface. Bat now mark the accompanying experience. A faint obscuration will not, like an extreme one, be habitually followed by a strong tactual impression and a subsequent contraction. If caused by a great mass passing at some distance, there will probably be no collision — no tactual impression at all. If caused by a little mass which is very near, the collision that follows will be comparatively slight — so slight as not to excite a violent contraction, but only such tension in the muscular apparatus as is seen in any creature about to seize upon prey. This is by no means an assumption. Among animals in general, ourselves included, a nervous impression which, if slight, simply rouses attention and braces up the muscles, causes convulsive contortions if intense. It is there- fore a deduction from a well-established law of the nervo- muscular system, that a creature possessing this somewhat improved vision will, by a partial obscuration of light, have its muscles brought into a state of partial tension — a state fitting them, either for the seizure of a small animal should the partial obscuration be caused by the impending collision of one, or for sudden retreat into a shell should the obscura- tion be increased by the near approach of a larger animal. So that even from this simple advance there arises a some- what greater speciality and complexity in the inner relations answering to outer relations.
Instead of a stationary creature, suppose the creature contemplated to be one that habitually moves about in tho water; and suppose a further development of the eyes — a development consisting in enlargement of each retina, and subdivision of it into separate sensitive agents. In such a creature, the eyes are subject to perpetually-changing im- pressions produced by the objects amid which it swims. These impressions fall on different parts of its retinae, according to the positions of the objects making them. Laterally-placed bodies either affect one retina only, or one much more than the other. Bodies above have their images cast on the lower parts of its retinae, Bodies below, if visible at all, cast images on their upper parts. Of the im- pressions thus made, however, few are directly followed by tactual impressions: the creature's forward movement carries it away from the objects making them. Only when the im- pression made by a lateral object is both very strong and changes very rapidly — only when it is the impression pro- duced by an approaching larger animal, will there result any motor excitation. Faint and slowly- changing lateral impres- sions, not being habitually followed by tactual impressions, will not affect the actions. But now mark that there are certain visual impressions which, though not strong, are habitually followed by tactual ones of a particular kind. I refer to the visual impressions made by small objects in front. When, during the creature's passage through the water, certain parts of its two retinae are simultaneously affected by.impressions of moderate strength; it commonly happens that 'immediately afterwards, the feelers and head come in contact with something serving for food. A visual impression of a special kind, is followed by a tactual im- pression on the prehensile organs; and, consequently, by all those muscular actions which the presentation of food to them calls forth. The often-recurring succession will be tliis:— Slight excitation of a particular double group of re- tmal nerves; excitation of the nerves of the prehensile organ*; excitation of a special set, of muscles. And these INSTINCT. 439 tliree psycMcal states being habitually connected, must, by repetition in countless generations, become so coherent that the special visual impression will directly call forth the mus- cular actions by which prey is seized. Eventually, the sight of a small object in front will cause the various motions requisite for the capture of prey.
Here, then, we see how one of the simpler instincts will, under the requisite conditions, be established by accumu- lated experiences. Let it be granted that the more fre-* quently psychical states occur in a certain order, the stronger becomes their tendency to cohere in that order, until they at last become inseparable; let it be granted that this tendency is, in however slight a degree, inherited, so that if the experiences remain the same each successive generation bequeaths a somewhat increased tendency; and it follows that, in cases like the one described, there must eventually result an automatic connexion of nervous actions, corresponding to the external relations perpetually ex- perienced. Similarly if, from some change in the en- vironment of any species, its members are frequently brought in contact with a relation having terms a little more involved; if the organization of the species is so far developed as to be impressible by these terms in close suc- cession; then, an inner relation corresponding to this new outer relation wiH gradually be formed, and will in the end become organic- And so on in subsequent stages of pro- gress.
This of course is intended merely as a rude indication of the mode in which the general principles enunciated explain the development of instincts. The law of intelligence being .that the strengths of the inner cohesions between psychical states must be proportionate to the persistences of the outer relations symbolized; and the development of in- telligence in conformity with this law being, in all eases, of which we have direct knowledge, secured by the one simple principle that experience of the outer relations pro- SPECIAL SYNTHESIS.
duces the inner cohesions and makes the inner cohesions strong in proportion as the outer relations are persistent; it was requisite to inquire whether the intelligence concern- ing whose genesis we have no direct knowledge, had pro- bably a like origin. And reasoning deductively from the conditions of the case, we conclude that this same simple principle is sufficient to account for the facts— or rather, for a type of them. To trace out the actual development of instincts, in their infinite varieties and complications, must ever remain impossible: adequate data are not to be had. The foregoing is to be taken simply as an adumbration of the probable mode of development.