LECTURE VII REFLEXES AS ADAPTED REACTIONS

Pseudaffective reflexes afford opportunity for determining the painpath in the spinal cord. This ascends both lateral columns, chiefly the one crossed from side of stimulation. The “chloroform cry” in decerebrate animals. Mimesis of pleasure as compared with mimesis of pain. The bodily resonance of the emotions. The theory of James, Lange, and Sergi. Emotional expressions in dogs deprived of visceral and largely of bodily sensation.

It is of course as impossible to disprove as to prove that psychical events accompany, or that they do not accompany, the nervous reactions of the “spinal” animal. It is significant, however, that the best-known controversy (Pflu̇ger, Lotze) as to the psychical powers of the spinal cord, occurred prior to the advent of the Darwinian theory of evolution. This latter suggests how purposive neural mechanisms may arise. It furnishes a key to the genesis and development of adapted reactions and, among these latter, reflexes.

That a reflex action should exhibit purpose is no longer considered evidence that a psychical process attaches to it; let alone that it represents any dictate of “choice” or “will.” In light of the Darwinian theory every reflex must be purposive. We here trench upon a kind of teleology. It is widely and wisely held that natural knowledge pursues the question “how” rather than the question “why.” The “why” involves a judgment whose data lie so beyond present human experience and comprehension that self-abnegation in regard to the desire to attempt it is not only prudent, but to the unbiassed judgment a necessity. Yet the question has its humbler forms as well as its more general and ambitious.

Older writings on reflex action concerned themselves boldly with the purpose of the reflexes they described. The language in which they are couched shows that for them the interest of the phenomena centred in their being regarded as manifestations of an informing spirit resident in the organism, lowly or mutilated though that might be. Progress of knowledge has tended more and more to unseat this anthropomorphic image of the observer himself which he projected into the object of his observations. The teleological speculations accompanying such observations have become proportionately discredited.

Self-wounded in this way physiology became for a time extremely reticent about purpose, remaining simply objectively descriptive.

The impetus given to biology by the doctrine of adaptation under natural selection, felt so strongly by morphological studies, seems hardly as yet to have begun its course as a motive force in physiology. But signs begin to be numerous that such an era is at hand.^* The infinite fertility of the organism as a field for adapted reactions has become more apparent. The purpose of a reflex seems as legitimate and urgent an object for natural inquiry as the purpose of the colouring of an insect or a blossom. And the importance to physiology is, that the reflex reaction cannot be really intelligible to the physiologist until he knows its aim.

In general terms we may say that the effect of any reflex is to enable the organism in some particular respect to better dominate the environment. One often hears objection taken to the epithets — common in writings on biology — “lower” and “higher” as applied to organisms, plant and animal. Such objection seems valid if the phrase assumes that the “lower” organism any less perfectly fulfils its “purpose” or “design” than does the “higher,” or in those respects in which it has commerce with the environment is any less admirably adjusted than is the higher. But “lower” and “higher” maybe used without any connotation of that kind. In the course of evolution a number of organisms have become so adapted to the environment as to dominate it more variously and extensively than do other organisms. In that sense some organisms are higher and some are lower. In that sense man is the highest organism. And if evolution be a process of gradual and more or less uninterrupted course it is obvious that the highest form achieved will also be among the latest of the forms achieved. This grading of rank in the animal scale will be nowhere more apparent than in the nervous system in its office as integrator of the individual. The more numerous and extensive the responses made by a creature to the actions of the world around upon its receptors, the more completely will the bundle of reflexes, which from this standpoint the creature is, figure the complexity of the world around, mirroring it more completely than do the bundles of reflexes composing “lower” creatures.

The study of reflexes as adapted reactions evidently, therefore, includes reactions of two ranks. With the nervous system intact the reactions of the various parts of that system, the “simple reflexes,” are ever combined into great unitary harmonies, actions which in their sequence one upon another constitute in their continuity what may be termed the “behaviour” (Lloyd Morgan) of the individual as a whole. Into the intricate “purposes” (adaptations) traceable in these total reactions which constitute the creature’s behaviour as a social unit in the natural economy it is not our part to enter. Our part of the problem is a humbler one. In the analysis of the animal’s life as a machine in action there can be split off from its total behaviour fractional pieces which may be treated conveniently, though artificially, apart, and among these are the reflexes we have been attempting to decipher. We cannot but feel that we do not obtain due profit from the study of any particular type-reflex unless we can discuss its immediate purpose as an adapted act.

When we try to assign what we may in this restricted sense call its “purpose” to any particular reflex, the data for an answer are gathered in the main from one or other of the conditions attaching to the reaction. The mode of the adequate stimulus is one of these. The time-relations and spatial form of the response are others. The broad pressure applied under the foot-pad which seems the adequate stimulus²⁵² for the “extensor-thrust” and the brief forcible straightening of the limb which constitutes the response suggest that that reflex has its purpose in the execution of an act in the series of movements of stepping in the animal’s locomotion. And the recent analysis of Philippson³⁰⁹ demonstrates that such an act occurs in the reflex trotting and galloping of the dog. Again, the connection between the tickling irritative stimuli which seem “adequate”²⁵² for the “scratch-reflex,” and the scratching movement itself which results, suggests that the purpose of that reflex is a grooming of the skin to protect that organ against parasites which infest it and would confuse its function as a receptive surface reacting to more significant environmental stimuli.

Grainger’s¹⁶ conclusion was that spinal cutaneous reflexes “are either of a preservative character or resemble the movements which the functions of the organ require.” From the skin of the spinal creature reflex movements resembling those executed by the normal individual in preening or cleansing itself are of widespread occurrence. Together with the preening actions of the spinal fly,⁸⁴ grasshopper, Astacus,¹⁷⁸ etc., there fall into this category the movement by which the spinal frog wipes irritants from its back or head; the “nettoyage” by the tortoise;¹⁷⁶ the posturing of the hind limbs and tail of the spinal dog concurrently with reflex defaecation,²⁵² tending to keep the body from being soiled; and the “scratch-reflex” and the “shake-reflex”^166a of the spinal dog. The conjunctival reflex protecting the cornea, essentially a cutaneous and from the broad point of view a spinal reflex, is similarly preservative of the part whence it is initiated.

There are of course two modes of preservation, namely, escape and defence. Parts that can move themselves seem reflexly to employ the former. The spinal frog’s foot is drawn out of harm’s way when irritated; so also in the cat and dog. But parts that cannot of their own motion withdraw themselves effectively seem to invoke defensive movements from adjacent motile parts. The spinal frog’s flank, when irritated, is defended by the hind limb, which comes up and removes the irritant from the flank, the flank itself also shrinking away somewhat. Similarly in the scratch-reflex, the distant limb is brought up to the defence of the irritated shoulder or flank. There is indeed one, rarely exemplified, group of reflexes in which the organ is sacrificed for the preservation of the rest of the individual. In certain forms, e. g. Asterias, Cometula, Ophiurus, Arachne, Carcinus, a limb pulled upon violently or long suddenly ruptures itself and is shed. These actions have been shown by Fredericq to be reflexes, employing muscular contraction. Such reactions exhibit well how absolutely the nervous system is adapted to minister to the requirements of the organism as an integrated whole, and the position of that system as a keystone in the upbuilding of the solidarity of the individual.

But the assignment of a particular purpose to a particular reflex is often difficult and hazardous. The difficulty is inversely as the amplitude of the field covered by the reflex-effect. A slight movement confined to a single limb, or a transient rise of blood-pressure observed alone, is open to many interpretations and admits of no security of inference. It is a fractional reaction that may belong to any of many general reactions of varied aim.

When a reflex is elicited faintly in a spinal animal it occurs simply at the focus, so to say, of its area of distribution, and owing to the restricted character of its features its meaning may be difficult or impossible to read. It is in my experience only by repeated observations of a reflex under various circumstances of its development that as a rule its significance becomes clear. The accessory parts of it are often instructive concerning the whole. In the scratch-reflex of the dog, besides the rhythmic scratching movement of the hind limb, say of the right, there is steady extension of the left hind limb, and steady extension with some abduction of the two fore limbs. The accessory parts of the reflex, namely those in the three limbs which are not scratching, are also contributory to the same effect as in the scratching movement in the right hind limb itself. They steady the dog and secure the stability of its body during the performance of the scalptor act.

In the “flexion-reflex” of the hind limb excited by noxious stimuli, e. g. a prick or a faradic current, the limb itself is drawn up, — if weakly, chiefly by flexion at the knee; if strongly, by flexion at hip as strongly as at knee. At the same time the crossed hind limb is thrown into action, primarily in extension, but this is soon followed by flexion, and alternating extension and flexion is the characteristic result. The rate of this alternation is about twice a second. That is to say, the foot which has stamped on the thorn is drawn up out of way of further wounding, and the fellow hind limb runs away; and so do the fore legs when — which is more difficult to arrange, owing to the height of the necessary spinal transection — they also are included, fairly free from shock, within the “spinal” animal.

Spinal shock. One of the experimental difficulties in deciphering the purport of a spinal reflex is the phenomenon known as “shock.” “If in a frog the spinal marrow be divided just behind the occiput, there are for a very short time no dias-taltic actions in the extremities. The diastaltic actions speedily return. This phenomenon is ‘shock.’“ (Marshall Hall.)²³

Whytt had, a century previous to Hall, drawn attention to the same phenomenon, although assigning to it no descriptive term. The whole of that depression or suppression of nervous functions which ensues forthwith upon a mechanical injury of some part of the nervous system and is of temporary nature may be conveniently included as “shock.” Goltz considered it entirely a collection of inhibition phenomena. Among laboratory animals it is in the monkey that, on the whole, “spinal shock” appears at maximum.

Spinal shock appears to take effect in the aboral direction only.¹⁸³, ²⁰⁵ Section behind the brachial enlargement disturbs little if at all the reactions of the fore limb, although the number of headward running channels of conduction ruptured by such a section is enormous. Striking instances of the absence of headward spread of the depression due to “shock” are afforded by transections abutting on the lower edge of the fifth cervical segment; these depress the respiratory activity of the phrenic motor cells hardly at all, even momentarily. On the aboral side of the transection depression is profound. Analogously, the sudden cutting off of all that stream of centripetal impulses continually pouring for conscious and subconscious elaboration into the encephalon from the cutaneous, articular, and muscular sense-organs of the tail, limbs, trunk, and neck, and from the viscera, seems to disturb the reactions of the head and brain little or not at all.

After high cervical transection, “shock” appears more severe in the fore limbs than in the hind. For an hour or so it may be difficult to elicit any reflex movement from skin innervated behind the transection, whether by mechanical, thermal, or electrical stimuli.

The view of Goltz and his school that “spinal shock” is a long lasting inhibition due to irritation by trauma is not, I think, really tenable. The argument implies, if it does not explicitly state, that the trauma, by its damage and by its subsequent processes of inflammatory reaction, formation of scar-tissue, etc., acts as a stimulus, exciting inhibition that depresses or suppresses reflex activity in adjacent and even remote arcs of the central nervous system. Against this explanation militate several facts. Firstly, the shock takes effect almost exclusively in the aboral direction. Were the mere irritative action of the trauma the cause, it is not easy to see why the nervous centres near the trauma should not be depressed on either side of, for instance, a spinal transection, headward as well as backward. Secondly, experiments of the following kind give results difficult to reconcile with the view. When in the dog complete transection of the spinal cord through the eighth cervical segment is practised, a severe fall in the general arterial blood-pressure ensues, and vasomotor reflexes cannot be elicited. But in the course of some days this is largely recovered from, and after some weeks the blood-pressure will, with the animal in the horizontal position, often be found practically normal. When the animal is then anaesthetized and curarized, artificial respiration being maintained, it is usually easy to obtain on stimulation of the central ends of divided afferent or mixed nerves, for instance of the internal saphenous nerve, good and often very large vasomotor reflexes, the blood-pressure rising fifty millimeters and more (Fig. 67). These reflexes upon the vascular musculature are purely spinal, since the cord has been divided just headward of the thoracic region. Then, while these spinal vasomotor reflexes are regularly elicitable and serve as a guide to the reflex activity of the cord behind the transection, I have transected the cord again a couple of segments behind the original transection. This section excites an immediate transient rise in the arterial pressure, lasting about a minute, and succeeded by a gradual fall. The arterial pressure, then, in my experience sinks to an equilibrium of pressure hardly lower than its mean prior to this second transection. There is none of that deep depression which ensued on the first trauma, though the second trauma has been practically qua trauma a complete repetition of the former one. If the fall of general blood-pressure be regarded as part, and a severe part, of the “spinal” shock which ensues on spinal transection in the cervical region, the absence of that fall on repeating practically the same trauma must signify that the second trauma is not followed by the shock that followed the first trauma. Moreover, reflex heightenings of blood-pressure such as were regularly obtainable just prior to the second transection are obtainable immediately, i. e. four minutes, after the second spinal transection. The first trauma causes temporary deep depression of the spinal tonus of the vascular system and temporary abolition of vascular reflexes. The second trauma causes practically no depression, even transient, of the re-established tonus of the vascular system nor of the pressor spinal vascular reflexes that have become similarly re-established. It may perhaps be objected that the vascular tonus established subsequent to the first spinal transection is of peripheral mechanism and outside the spinal cord itself. That that is not its main factor is shown by the further deep depression of vascular tonus which occurs when the spinal cord in the thoracic region is itself not merely transected but destroyed.

The trauma qua trauma is as severe in the first instance as in the second. In these experiments, therefore, the “shock” is not due to the trauma qua trauma. It seems to depend simply on solution of continuity of nervous channels, and this solution is practically equally great whether the actual trauma itself be relatively slight (a clean, sharply cut transection) or relatively severe (a contused and jagged transrupture), so long as in the two cases it involves an equal amount of the transverse area of the cord. The practical absence of spinal “shock” on repetition of the trauma further back is explicable by its then causing little further aggravation of the interruption of the nervous channels concerned with vascular tone and vascular reflexes, those channels having already been ruptured by the previous transection somewhat further headward.

Similarly the flexion-reflex of the hind limb, though it suffers considerably from shock after transection of the cord in the hinder cervical or thoracic region, when it has recovered is but little, and but briefly, depressed by a second transection made behind the previous. In this case also trauma does not, therefore, account for the spinal shock. The shock following the trauma is proportioned not to the mere wound, but to the number and character of the descending nerve-paths through which the lesion breaks. Porter’s^{157 a} well-known experiment on the respiratory intraspinal path from the bulb to the phrenic neurones points to the same conclusion.

There remains the further question as to whether spinal “shock” is a phenomenon of inhibition. A reflex during its depression by spinal shock does not present the features it shows when reduced by inhibition so much as features resembling those characteristic of it when fatigued. The scratch-reflex under spinal shock (Figs. 68, 69) shows irregularity of rhythm, slow protracted relatively feeble beats, and speedy onset of temporary inexcitability, features which characterize it when nearly tired out (comp. Fig. 62, 63, Lect. VI). So also with the flexion-reflex of the leg. In the period of depression by spinal shock the reflex is feeble even under strong excitation, is relatively short-lasting, and on cessation of the exciting stimulus shows little of the prolonged after-discharge that it is prone to show at other times: it also tires out then with abnormal rapidity. The scratch-reflex in spinal shock of pronounced degree fails to be elicitable by electrical stimulation at all, though still elicitable by rubbing. This indicates the greater efficacy of a stimulus more nearly like the adequate.

The condition of the spinal reflex-arcs in spinal shock appears to resemble a general spinal fatigue rather than an inhibition. It renders difficult and uncertain the process of conduction along the reflex-arc as judged by the discharge from the terminal neurone. This suggests a loosening of nexus between the links of the neurone-chain composing the arc; a defect of transmission at the synapse. Such a conception of the disorder accords well with the suggestion of v. Monakow²⁴¹ that a “diaschizis” takes place between the conducting cells, his “schalt-zellen” failing to perform their normal function as connecting elements.

I think, therefore, that spinal shock is neither due to irritation by trauma, nor in the main a phenomenon of inhibition. The rupture of certain aborally conducting paths appears to induce it. Which these paths exactly are is matter for research. After cervical transection separating the cord from the bulbar vaso-motor centre, the phenomenon might be attributable to the invariably severe fall of general arterial pressure. But this cannot be the chief explanation, for: (1) the head does not participate in the “shock,” although participating in the low blood-pressure; (2) with post-thoracic transection the body region distal to the spinal lesion exhibits shock as severe as after cervical transection, though there is no fall of blood-pressure; (3) transection anterior to the bulbar vasomotor centre but posterior to the pons leaves the blood-pressure unreduced but the spinal shock severe.

The shock is more profound in the monkey than in other animals observed in the laboratory. This might suggest a cerebral origin for the paths implicated. But ablation of the hemispheres does not induce anything like the depth of spinal depression induced by transections behind the pons. The much severer character of the depression when the transection passes behind the pons indicates an aborally directed influence from some nucleus of the pontine or midbrain system, driven probably by the great cranial receptors of otic labyrinth and eye, reinforced by impulses from the cord itself. The great influence on spinal centres of a cranial mechanism in this region, driven by the otic labyrinth, is illustrated by Ewald’s¹³⁷ proposed name “tonus labyrinth” for the end-organ of the octavus nerve. The great severity of shock in the monkey would accord with high exercise of function of this apparatus in an animal endowed with such variety and range of skeletal movement.

In the monkey and in man spinal shock is not only peculiarly intense but peculiarly long lasting. The withdrawal from the isolated cord of influences it is wont to receive from centres further headward may induce an alteration of trophic character in spinal cells — an “isolation dystrophy”¹⁸³ — visible, it may be, as Nissl’s chromatolysis. This “isolation-dystrophy” ensuing on shock would add itself as a longer lasting, in some elements perhaps a permanent, depression. Certainly spinal transection is followed in the monkey by longer lasting “shock” — included in which I suspect is “isolation-dystrophy” — than in other animal types observed in the laboratory. My results in monkeys bore out that which Bastian,¹²⁹ Bowlby,^131a and Bruns,¹⁴⁰ contrary to previous observers, have described as the typical condition in man after spinal injury completely severing the cord. Thus, I found the knee-jerk sometimes inelicitable during a month or so after midthoracic transection in the monkey, whereas in the rabbit its abeyance lasts usually but ten minutes or a quarter of an hour.

It is noteworthy that spinal shock takes effect on just those tissues which waste when the synaptic nervous system is destroyed — namely the skeletal muscles. Where the primitive diffuse nervous system, the nerve-net, exists, as in the visceral and vascular musculature, neither “spinal shock” nor atrophy occur consequently to spinal transection. In the skeletal muscles the “spindles” do not waste.¹⁵³ Jamin found that the disuse-wasting of the muscles in spinal dogs which had been daily exercised in reflex actions in my laboratory was much less than in other dogs he examined. The organs on which “shock” falls least heavily are those which suffer least even after exsection of the spinal cord itself.

The deeper depression of reaction into which the higher animal as contrasted with the lower sinks when made “spinal,” appears to me¹⁹⁴ significant of this, that in the higher types, more than in the lower, the great cerebral senses actuate the motor organs and impel the motions of the individual.

“Spinal shock” does not fall upon all reflexes with equal severity. Noci-ceptive reflexes suffer relatively slightly. In the dog, after spinal transection in the posterior part of the cervical region, the reflexes acting on the muscles of the hind limb show less severe and shorter-lasting depression in regard to the flexion-reflex and in regard to the scratch-reflex than to the extensor-thrust. That may explain why a number of observers have not obtained any homonymous reflex of extension in the spinal mammal. The crossed extension-reflex, which is really a part of the great reflex of which homonymous flexion is the more prominent feature, recovers from spinal shock earlier than does the extensor-thrust.

There is variability in the order of recovery of the various spinal reflexes of the dog from spinal shock. Occasionally the scratch-reflex returns as early as the flexion-reflex. Although usually in the hind limbs of the spinal dog no extensor rigidity develops, in some individuals it does so. The limbs are kept extended at knee and ankle even to a degree that it is difficult to break through by the inhibition accompanying elicitation of the flexion-reflex on stimulation of the foot. It is not difficult to see how this may come about. Some incidental circumstance determining the preponderance of some passive attitude of the limbs during the early days succeeding the lesion may, by its influence on the interaction of the recovering spinal arcs, impress an unwonted reflex habit upon the limbs. It is not uncommon to find, especially in the spinal monkey, I think, differences in the reflex condition of the right and left limbs, even although the spinal transection has given a perfectly symmetrical spinal lesion. Such inequality or dissimilarity of the spinal reflexes right and left does not necessarily afford any evidence that the spinal lesion is asymmetrical. Intercurrent circumstances suffice to impress slightly different reflex habits on the two limbs, and in one and the same individual the reflex habits of each limb may vary somewhat from period to period (cf. Lewandowsky on the production of hemiplegic contracture).

Local sign in reflexes. The locus of the stimulus plays an important part in determining the nature of the reflex evoked. This influence of the location of the stimulus on the resulting reflex movement has been one of the features most studied in reflex action. It furnishes a large part of the direct evidence of the “purposive” character of spinal reflexes.¹

The rule of spatial proximity given above partly expresses the influence of this factor. Much that was mentioned regarding long irradiation illustrates it further. Though the importance of the locus is high when broadly taken, it does not appear obvious as attaching to small differences of location in a more or less homogeneous receptive field or area. Yet in such a field the reflexes, though similar, are demonstrably not identical.¹⁸³ In the spinal monkey, excitation of the outer edge of the planta while causing dorso-flexion at ankle, in doing so generally brings the peronei into play more than is the case when the flexion is excited from the inner edge of the planta; then tibialis anticus predominates, causing some inversion. In the frog, excitation of the skin of the dorsal aspect of the knee, and of the ventral aspect respectively, alike evoke flexion at hip, knee, and ankle, but in the former case the foot is somewhat everted, in the latter somewhat inverted. We must allow that the centripetal impulses, although they yield no sensation, yet possess, to borrow a term from the psychologist, “local sign.” In the naked eye Medusa, called on account of its localizing reflexes Tiaropsis indicans,⁷² the manubrium deflects itself towards the stimulated part of the nectocalyx; its tip is brought with precision to meet the concurrently contracted inbent portion of the nectocalyx. If one point of the nectocalyx be irritated, and while the manubrium is applied to that point, then another, the manubrium will leave the first point and move over to the second. In this way it may be made to indicate successively a number of points of irritation. “After a series of such irritations the manubrium subsequently continues for some time to visit first one and then another of the points which have been irritated.”⁷² A cut between the base of the manubrium and the point of irritation in the bell destroys the localization, though movement occurs toward some part of the quadrant of the bell containing the site of stimulus; but the accuracy of the localization is reduced. The reaction recalls the bending of the tentacles of Drosera⁶² in the direction needful to reach the seat of stimulation on the leaf. The headless bee stings in response to stimulation of the under-surface pretty accurately at the site of irritation.¹⁷⁸ In the “spinal” crayfish, if one leg is caught it is flexed and drawn up, and soon all the others, if the leg is not released, are brought round it and push at the hand holding the limb.^79a The yellow clover-fly will, after decapitation, stand cleaning its wings with its hind legs, and clean its “three pairs of legs, rubbing them together in a determined manner, and raising its fore legs vainly in air as if searching for its head to brush up.”⁸⁴ But in Astacus the accuracy of localization is much impaired on the crossed side by cutting the cross commissures combining the ganglia most closely concerned with the reaction.¹⁸⁵ This recalls the effect of the tangential cut in the nectocalyx of Tiaropsis.⁷²

In a reflex reaction exhibiting “local sign” in the above sense, the afferent impulses involved are divisible into several groups according to their place of origin. There must be (1) a group originated at the seat of stimulus, (2) a group initiated in the motor and mobile organs reflexly set in action, and (3) in some cases a group arising at the distant spot to which the movement is directed. Regarding this last group an experiment illustrates its extinction without extinction of the “local sign.” Thus, in Astacus,^79a after section of the nerve-cords behind the mouth, when, therefore, the hind creature without mouth has lost all nervous connection with the front creature possessing the mouth, food given to the claws of the hind creature is still at once and accurately carried by them to the mouth, and this latter may refuse to take the morsel brought. In the grasshopper,^178a after extirpation of the supra and suboesophageal ganglia (entire brain), the front leg is protracted, and in the normal way catches the antenna, and the usual movements of cleaning the antenna go on, although the antenna has entirely lost its innervation owing to the destruction of the brain. Regarding the second mentioned group of afferent impulses, H. E. Hering¹⁶² has made the interesting observation that the “cleansing” reflex of the spinal frog which brings the foot to a seat of irritation on the dorsal or perineal skin is accurately executed after severance of the afferent spinal roots of the limb itself. In the same way the bulbo-spinal frog brings the fore limb to the snout when the snout is stimulated after section of the afferent roots of the fore limb. The scratch-reflex I find executed without obvious impairment of direction or rhythm when all the afferent roots of the scratching hind limb have been cut through. In the execution of these spinal reflexes, therefore, the most important afferent factor as regards “local sign” is the afferent channel from the place of initiation of the reflex.

Pseudaffective reflexes. If we turn to reflex-effects excited by nocuous stimulation of the skin but having for their field of development a wider conjunction of reflex-arcs and consequently a wider mechanism of reflex expression, the reflex response seems to indicate yet more clearly the “purpose” of the reflex.

If from the cat under deep chloroform narcosis the cerebral hemispheres and part of the thalami be removed, on relaxing the narcosis a number of motor reactions can be observed against the background of “decerebrate rigidity.”¹⁸² Among these reactions are some mimetic movements simulating expression of certain affective states. These “pseudaffective” reflexes Woodworth and myself²⁷⁵ have endeavoured to use for elucidation of the spinal path conducting those impulses that, were the brain intact, would, we may presume, evoke “pain.” The search for such a path is, as regards channels from skin, a search for a path as specific as those of the special senses. The truncation of the brain of the mammal at the mesenceph-alon annihilates the neural mechanism to which the affective psychosis is adjunct. But it leaves fairly intact the reflex motor machinery whose concurrent action is habitually taken as outward expression of an inward feeling. When the expression occurs it may be assumed that, had the brain been present, the feeling would have occurred. Pain is the psychical adjunct of a protective reflex. A spinal translesion which prevents occurrence of the expression in response to a stimulus that previously excited the expression has therefore been regarded by us in the following experiments to be such as would, were the brain present, induce analgesia in regard to that stimulus. Even apart from that assumption, it is clear that such a lesion can be used for determining the conducting path of a noci-ceptive reaction. The spinal path concerned with the forward transmission of these impulses can therefore be designated not merely a headward path, but, having regard to the character of the reaction, the headward path for noci-ceptive (p. 266) reactions.

The reflex-effect observed has presented the following elements: diagonal cyclic movements of the limbs as in progression (sometimes producing progression), turning of head and neck toward the point stimulated; opening of the mouth, retraction of the lips and tongue, movement of the vibrissae; snapping of the jaw; lowering of the head; opening of the eyelids, dilatation of the pupils; vocalization angry in tone (snarling), sometimes plaintive; and with these a transient increase of arterial blood-pressure. These reactions appear not only in combination, but sometimes singly or in small combinations. The most readily elicitable are movements of the vibrissae, opening of the mouth with retraction of the tongue, and lowering of the head; but though in some cases vigorous and prompt they never amount to an effective action of attack or escape. A characteristic feature of their ineffectiveness is their brief duration. The movement, even when most vigorous and prompt, dies away rapidly, to be succeeded in some cases by a few weaker repetitions, each in succession weaker and more transient than the last. Thus, the movements of the head may recur three or four times in response to a single stimulus, or the vocalization be repeated in a diminishing series for a minute or so.

Our method has been to compare by means of the above reaction the effect of two stimuli symmetrically but successively applied on opposite sides of the body, after a semisection or other lesion of the spinal cord headward of the entrance of the nervepath stimulated.

After semisection at the 13th thoracic level the pseud-affective reaction was obtained by stimulation of either sciatic trunk, but more vigorously and promptly from the nerve of the side of the semisection: from this nerve also the reaction was evoked by weaker faradization. This indicates that the headward pathway taken by the impulses eliciting the vocal and other pseudaffective reactions is from the hind limb both crossed and uncrossed, but is more largely crossed. From our experiments we are able to exclude the dorsal spinal column as the main path of conduction. Sections of both dorsal columns made no appreciable difference in the reaction to the stimulus; neither did faradization of them evoke the reaction. The median portion of the ventral column has sometimes been trespassed on in making the semisection of the opposite side; this extension of the lesion has not prevented the reaction from occurring. In one case the whole gray matter of both halves of the cord was found at the autopsy to be heavily infiltrated and ploughed up with extravasated blood at the level of the semisection and for several millimetres both ahead and behind it. It must have been largely, if not completely, thrown out of function. Yet the pseudaffective reaction remained very brisk.

If, therefore, neither the dorsal nor the ventral column nor the gray matter affords the pathway for the noci-ceptive (algesia) impulses, the lateral column alone is left to them. This conclusion is confirmed by direct experiment. After transection of one lateral column alone the pseudaffective reaction is elicited from either lateral half of the body behind the lesion; after further section of the opposite lateral column, all pseudaffective reaction at once ceases to be elicitable from either half of the body behind the lesion. It is probable that in the posterior thoracic and lumbar segments this headward path is that already signalized by A. Fröhlich and myself²²² as inhibiting, under direct faradization, the rigidity of the triceps brachii in the decerebrate cat.

We concluded from our observations (1) that the lateral column furnishes the headward path in the spinal cord for noci-ceptive (algesic) arcs; (2) that each lateral column conveys such impulses from both lateral halves of the body, and somewhat preponderantly those from the crossed half; and (3) that this is true for these arcs whether they be traced from skin, muscles, or viscera.

It is noteworthy that the “chloroform” or “ether cry,” that peculiar vocalization emitted by men and animals during certain stages of anaesthetization, was often uttered²⁷⁵ by decerebrate cats during the continued administration of the anaesthetic after decerebration. This vocalization does not necessarily mean an imperfect anaesthetization or any persistence of consciousness, since in our animals the whole cerebrum and the “’tween”-brain had been ablated when the administration of the vapour still evoked the vocalization typically.

The crying of the young infant has been noticed in hemi-cephalic children to be strong and of usual character even in total absence of the cerebrum and midbrain (Sternberg and Latzko²⁶⁷). These malformed infants seem to react as do normal of the same age to stimuli that, judging from adult experience, are unpleasant. They cry or whimper, pucker the mouth, and retract the head. The drawing down of the angles of the mouth and the drawing down of the lower lip seem indicative of pain: pouting of the lips—a mimetic movement common also in the young gorilla, chimpanzee, and macaque—seems to indicate displeasure. Nothnagel and others incline to regard the optic thalamus as the seat of the nerve-centres of mimetic expression. Experiments on animals and the observations on hemicephalic children just referred to seem to contradict this. But we must remember that various grades of mimetic movements exist—and some seem phylogenetically much older than others. The congenital have to be distinguished from those that are acquired. The mimesis of the infant is not that of the adult. The latter may depend on the thalamic region; much of the former seems to be a reaction for which neither the forebrain nor midbrain are necessary. In the decerebrate cat we could never evoke such mimesis as might, had the cerebrum been present, have been indication of pleasurable sensation. Never, for instance, could purring be elicited, although its opposite, snarling, was obtained so easily. The decerebrate dogs observed by Goltz¹³⁵ responded to almost all forms of skin stimulus by growling, as if in resentment. Thus, they did so when lifted from their cage to be fed each midday. No mimesis indicative of pleasure was ever obtained from them. Pain centres seem to lie lower than pleasure centres. As far as I can find from reference to books and the experience of colleagues, “pain” is unknown as an aura in cortical epilepsy, or at least is of equivocal occurrence. No region of the cortex cerebri has been assigned to pain. Such negative evidence gives perhaps extraneous interest to the ancient view, represented in modern times by Schopenhauer, that pleasure is an absence of pain.

Bodily resonance of emotions. Some sensations are neutral or devoid of affective tone, while others are rich in affective tone. The development of these latter is closely connected with the origin of the coarser emotions. A physiological interest attaches to these states of emotion since certain reactions of the bodily organs are, as is well known, characteristic of them. That marked reactions of the nervous arcs regulating the thoracic and abdominal organs and the skin contribute characteristically to the phenomena of emotion has been common knowledge from time immemorial.

To this bodily resonance of the emotions has in recent years been assigned by some authorities a prominent rôle in the mechanism of the production of the emotional state itself in certain of the coarser emotions. Instead of the emotional state beginning, as Ladd²¹³ puts it, as “a sort of nerve storm in the brain, whence there descends an excitement which causes commotion in the viscera and vascular regions—thus secondarily inducing an organic reverberation”—the view has been advanced that the cerebral and psychological processes of emotion are secondary to an immediate reflex reaction of vascular and visceral organs of the body suddenly excited by certain stimuli of peculiar quality.

Of points where physiology and psychology touch, the place of one lies at “emotion.” Built upon sense-feeling much as cognition is built upon sense-perception, emotion may be regarded almost as a “feeling,”—a feeling excited, not by a simple little-elaborated sensation, but by a group or train of ideas. To such compound ideas it holds relation much as does “feeling” to certain species of simple sense-perceptions. It has a special physiological interest in that certain visceral reactions are peculiarly colligate with it. Heart, blood-vessels, respiratory muscles, and secretory glands take special and characteristic part in the various emotions. These viscera, though otherwise remote from the general play of psychical process, are affected vividly by the emotional. Hence many a picturesque metaphor of proverb and phrase and name—“the heart is better than the head,” anger “swells within the breast,” “Richard Coeur de Lion.” It was Descartes¹ who first promoted the emotions to the brain. Even last century Bichat wrote,⁹ “The brain is the seat of cognition, and is never affected by the emotions, whose sole seat lies in the viscera.” But the brain is now thought to be a factor necessary in all higher animals to every mechanism whose working has consciousness as an adjunct.

What is the meaning of the intimate linkage of visceral actions to psychical states emotional? To the ordinary day’s consciousness in the healthy individual the life of the viscera contributes little at all, except under emotion. The perceptions of the normal consciousness are rather those of outlook upon the circumambient universe than inlook into the microcosm of the “material me.” Yet heightened beating of the heart, blanching or flushing of the blood-vessels, the pallor of fear, the blush of shame, the Rabelaisian effect of fright upon the bowel, the secretion by the lacrymal gland in grief, all these are prominent characters in the pantomime of natural emotion. Visceral disturbance is evidently a part of the corporeal expression of emotion. The explanation is a particular case in the problem of movements of expression in general. The hypothesis of evolution afforded a new vantage point for study of that question. The bodily expressions of the “coarser or animal emotions” are largely common to man and higher animals. This point of view is exemplified by Darwin’s argument⁵⁰ concerning the contraction of the muscles round the eyes during screaming. “Children, when wanting food or when suffering in any way, cry out loudly, as do the young of most animals, partly as a call to their parents for aid, and partly from any great exertion serving as relief. Prolonged screaming inevitably leads to the engorging of the blood-vessels of the eye; and this will have led at first consciously and at last habitually to the contraction of the muscles round the eyes in order to protect them.”⁵⁰ Herbert Spencer wrote:⁸⁵ “Fear, when strong, expresses itself in cries, in efforts to hide or escape, in palpitations and tremblings; and these are just the manifestations which would accompany an actual experience of the evil feared. The destructive passions are shown in a general tension of the muscular system, in gnashing of the teeth and protrusion of the claws, in dilated eyes and nostrils, in growls: and these are weaker forms of the actions that accompany the killing of prey.” In short, the bodily expressions of emotion are instinctive actions reminiscent of ancestral ways of life.

They must have an explanation the same in kind as that of other instinctive movement. There is no real break between man and brute even in the matter of mental endowment. The instinctive bodily expressions of emotion arose, in the opinion of those quoted above, as attitudes and movements useful to the animal for defence, escape, seizure, embrace, etc. These as survivals have become symbolic for states of mind. Hence an intelligible nexus between the muscular attitude, the pose of feature, etc., and the emotional state of mind. But between action of the viscera and the psychical state the nexus is less obvious. This latter connection adds a difficult corollary to the general problem.

The fact of the connection is on all hands admitted, but as to the manner of it opinion is at issue. Does (1) the psychical part of the emotion arise and its correlate nervous action then excite the viscera? Or (2) does the same stimulus which excites the mind excite concurrently and per se the nervous centres ruling the viscera? Or (3) does the stimulus which is the exciting cause of the emotion act first on the nervous centres ruling the viscera, and their reaction then generate visceral sensations; and do these latter, laden with affective quality as we know they will be, induce the emotion of the mind? On the first of the three hypotheses the visceral reaction will be secondary to the psychical, on the second the two will be collateral and concurrent, on the third the psychical process will be secondary to the visceral.

To examine the last supposition first. It is a view which in recent years has won notable adherents. Professor James writes:^{124 *} “Our natural way of thinking about these coarser emotions (e.g. “grief, fear, rage, love”) is that the mental perception of some fact excites the mental affection called the emotion, and that this latter state of mind gives rise to the bodily expression. My theory, on the contrary, is that the bodily changes follow directly the perception of the exciting fact, and that our feeling of the same changes as they occur IS the emotion.” “Every one of the bodily changes, whatsoever it be, is FELT acutely or obscurely, the moment it occurs. If the reader has never paid attention to this matter, he will be both interested and astonished to learn how many different local bodily feelings he can detect in himself as characteristic of his various emotional moods.” “If we fancy some strong emotion and then try to abstract from our consciousness of it all the feelings of its bodily symptoms we find we have nothing left behind, no ‘mind-stuff’ out of which the emotion can be constituted, and that a cold and neutral state of intellectual perception is all that remains.” “If I were to become corporeally anaesthetic, I should be excluded from the life of the affections, harsh and tender alike, and drag an existence of merely cognitive or intellectual form.”

Professor Lange^106a traces the whole psycho-physiology of emotion to certain excitations of the vasomotor centre. For him, as for Professor James, the emotion is the outcome and not the cause or the concomitant of the organic reaction; but for him the foundation and corner-stone of the organic reaction is as to physiological quality vascular, namely, vasomotor. Emotion is an outcome of vasomotor reaction to stimuli of a particular kind. This stimulus induces a vasomotor action in viscera, skin, and brain. The change thus induced in the circulatory condition of these organs induces changes in the actions of the organs themselves, and these latter evoke sensations which constitute the essential part of emotion. It is by excitation of the vasomotor centre, therefore, that the exciting cause, whatever it chance to be, of emotion produces the organic phenomena which as felt constitute for Lange the whole essence of emotion. The teaching of Professor Sergi^{152, 177} closely approaches to that of Lange.

The views of James, Lange, and Sergi have common to them this, that the psychical process of emotion is secondary to a discharge of nervous impulses into the vascular and visceral organs of the body suddenly excited by certain peculiar stimuli, and that it depends upon the reaction of those organs. Professor James’s position in the matter is, however, not wholly like that of Professor Lange. In the first place, he does not consider vasomotor reaction to be primary to all the other organic and visceral disturbances that carry in their train the psychological appanage of emotion; and Professor Sergi, though more nearly in harmony with Lange, agrees with James so far. In the second place, Professor James seems to distinctly include other “motor” sensations and centripetal impulses from musculature other than visceral and vascular, among those which casually contribute to emotion. Thirdly, he urges his theory as one completely competent only for the “coarser” emotions, among which he instances “fear, anger, love, and grief.” For Lange and Sergi the basis of apparition of all feeling and emotion is physiological, visceral, and organic, and has its seat for the former authority exclusively, and for the latter eminently, in the vasomotor system.

To obtain some test of this view is not difficult by experiment.^213a Appropriate spinal and vagal transection removes completely and immediately the sensation of the viscera and of all the skin and muscles behind the shoulder (Fig. 70). The procedure at the same time cuts from connection with the organs of consciousness the whole of the circulatory apparatus of the body. I have had under observation dogs in which this has been carried out. I will cite an animal selected because of markedly emotional temperament. Affectionate toward the laboratory attendants, one of whom had her in charge, toward some persons and toward several inmates of the animal house she frequently showed violent anger. Her ebullitions of rage were sudden. Their expression accorded with a description furnished by Darwin.⁵⁰ Besides the utterance of the growl, “the ears are pressed closely backwards, and the upper lip is retracted out of the way of the teeth, especially of the canines.” The mouth was slightly opened and lifted, the eyelids widely parted, the pupils dilated. The hair along the mid-dorsum, from close behind the head to a point more than half-way down the trunk, became rough and bristling.

The reduction of the field of sensation in this animal by the procedure above mentioned produced no obvious diminution of her emotional character. Her anger, her joy, her disgust, and when provocation arose, her fear, remained as evident as ever. Her joy at the approach or notice of the attendant, her rage at the intrusion of a cat with which she was unfriendly, remained as active and thorough. But among the signs expressive of rage the bristling of the coat along the back no longer occurred. On the other hand, the eyes were well opened and the pupils distinctly dilated in the paroxysm of anger. Since by the transection the brain had been shut out from discharging impulses via the cervical sympathetic the dilatation of pupil may have occurred by inhibition of the action of the oculomotor centre.

The coming of a visitor whose advent months before had elicited violent anger, again provoked an exhibition of wrath significant as ever. The expression was that of aggressive rage. The animal followed each movement of the stranger as though of an opponent, growling viciously. A cat with which she was never friendly, and a monkey new to the laboratory, approaching too near the kennel, excited similar outbursts. No doubt was left in our minds that sudden attacks of violent anger were still easily excited. But she also gave evidence daily that she had the accession of joyous pleasure and delight she had always shown at the approach of the attendant the first thing of a morning, or at feeding time, or when caressed by him, or encouraged by his voice.

Few dogs, even when very hungry, can be prevailed upon to touch dog’s flesh as food. Almost all turn from it with signs of repugnance and dislike. I had strictly refrained from testing this animal previously with regard to disgust at dog’s flesh offered in her food. Flesh was given her daily in a bowl of milk, and this she took with relish. The meat was cut into pieces rather larger than the lumps of sugar usual for the breakfast table. It was generally horse-flesh, sometimes ox-flesh. We proceeded to the observation thus: the bowl was placed by the attendant in the corner of the stall with milk and meat in every way as usual; but the meat was flesh from a dog killed on the previous day. Our animal eagerly drew itself toward the food; it had seen the other dogs fed, and evidently was itself hungry. Its muzzle had almost dipped into the milk before it suddenly seemed to find something there amiss. It hesitated, moved its muzzle about above the milk, made a venture to take a piece of the meat, but before actually seizing it stopped short and withdrew again from it. Finally, after some further examination of the contents of the bowl (it usually commenced by taking out and eating the pieces of meat), without touching them, the creature turned away from the bowl and withdrew itself to the opposite side of the cage. Some minutes later, under encouragement from us to try the food again, it returned to the bowl. The same hesitant display of conflicting desire and disgust was once more gone through. The bowl was then removed by the attendant, emptied, washed, and horse-flesh similarly prepared and placed in a fresh quantity of milk was offered in it to the animal. The animal once more drew itself toward the bowl, and this time began to eat the meat, soon emptying the dish. To press the flesh upon our animal was of no real avail on any occasion; the coaxing only succeeded in getting her to, as it were, re-examine but not to touch the morsels. The impression made on all of us by the dog’s behaviour was that something in the dog’s flesh was repulsive to her, and excited disgust unconquerable by ordinary hunger. Some odour attaching to the flesh seemed the source of its recognition.

It would be instructive for judging the part played by the cerebral hemisphere in the reactions of coarser emotion did we know whether repugnance to dog’s flesh as food would be exhibited by a dog after ablation of the cerebral hemispheres. Even the primitive emotions seem to involve perception—seem little other than sense-perceptions richly suffused with affective tone. Goltz’s¹³⁵ dogs after ablation of the hemispheres evinced signs of hunger, namely restlessness when their feeding hour was deferred. When a little quinine (bitter) was added to the sop of meat and milk the morsels taken into the mouth were at once rejected. No inducement or scolding modified this unfailing and unhesitating rejection. Goltz adds that he threw to his own house dog a piece of the same doctored meat. The creature wagged its tail and took it eagerly, then pulled a wry face, and hesitated, astonished. But on a look of encouragement from its master the dog swallowed it. He overcame his instinctive rejection of it, and thus, as Goltz remarks, by his self-control gave proof of the intact cerebrum he possessed.

Fear appeared clearly elicitable (as also in dogs with spinal cervical transection only, Fig. 71). The attendant approaching from another room of which the door stood open, chid the dog in high scolding tones. The creature’s head sank, her gaze turned away from her advancing master, and her face seemed to betray dejection and anxiety. The respiration became unquiet, but the pulse never changed its rate.

In the dog, after transection of the spinal cord, the regions of the body which have been thus made purely “spinal” continue their life in many respects normally. The hairy “coat” changes in spring. The oestral periods recur even when the transection is performed in puppyhood, and altogether headward of the spinal origin of the sympathetic system, e. g. at the cervical segment. Goltz⁵⁸ observed successful impregnation and parturition, and suckling completed without obvious abnormality. In my own observations^213a the natural instinct of the female toward the male at oestrum was seen indubitably displayed after the spinal cord had been transected in the cervical region more than a year previously.

It may be objected to these experiments that although the animals expressed emotion they may yet have felt none. Had their expression been unaccompanied by, and had they not led on to, trains of acts logically consonant with their expressed emotion, that objection would have weight. Where the facies of anger is followed by actions of advance and attack with all appearance of set purpose, I find it difficult to think that the perception initiating the wrathful expression should bring in sequel angry conduct and yet have been impotent to produce “angry feeling.”

A weaker point in such experimentation is that although the visceral and vascular and much of the muscular mechanism of emotional expression was cut off, a small but notable fraction of the latter, namely the facial, still remained open to react on the centres with which consciousness is colligate.

Nevertheless, in view of these observations the vasomotor theory of the production of emotion becomes, I think, untenable, also that visceral sensations or presentations are necessary to emotion. A mere remnant of all the non-projecting or affective senses was left, and yet emotion persisted. If I understand it aright, Professor James’ and Lange’s theory lays stress on organic and visceral presentations, but re-presentations of the same species might no doubt be put forward in their place. That would be a different matter. To exclude the latter hypothesis, the deprivation of vascular and organic sensation might have to date from a very early period of the individual life. Professor Lloyd Morgan writes^216a in respect to the above experiments, “The avenues of connection were closed after the motor and visceral effects had played their part in the genesis of the emotion on the hypothesis that the emotion is thus generated. Although new presentative data of this type were thus excluded, their re-presentative after-effects in the situation were not excluded.” But it is noteworthy that one of the dogs under observation had been deprived of its sensation when only nine weeks old. Disgust for dog’s flesh could hardly arise from the experience of nine weeks of puppyhood in the kennel.

We are forced back toward the likelihood that the visceral expression of emotion is secondary to the cerebral action occurring with the psychical state. There is a strong bond between emotion and muscular action. Emotion “moves” us, hence the word itself. If developed in intensity, it impels toward vigorous movement. Every vigorous movement of the body, though its more obvious instrument be the skeletal musculature of the limbs and trunk, involves also the less noticeable co-operation of the viscera, especially of the circulatory and respiratory. The extra demand made upon the muscles that move the frame involves a heightened action of the nutrient organs which supply to the muscles the material for their energy. This increased action of the viscera is colligate with this activity of muscles. We should expect visceral action to occur along with the muscular expression of emotion. The close tie between visceral action and states of emotion need not therefore surprise us.

That emotion is primarily a cerebral reaction obtains support from observations where the hemispheres of the brain have been removed. Goltz observed a dog kept many months in that condition. It on no occasion gave any evidence of joy or pleasure in commerce either with man or beast. Of sexual emotion it never gave a sign. Anger or displeasure, Goltz says, it repeatedly expressed, both by gesture and by voice. Save for these expressions of displeasure, it was indifferent and supremely neutral to its surroundings. We are, of course, in observations such as this, hopelessly cut off from introspective help. It can be urged that the expression of emotion might be provocable and nevertheless the psychical emotion remain absent. On such an hypothesis the same stimulus which excited the mind must excite concurrently and per se motor centres producing movement appropriate to an affective process in the mind. This is not improbable. All sensations referred to the body itself rather than interpreted as qualities of objects in the external world, tend to be tinged with “feeling.” Sense-organs which initiate sensations tinged with feeling tend to excite motor centres directly and imperatively. Hence in animals reduced to merely spinal condition stimuli calculated to produce pain (although, of course, unable to do so in a spinal animal) evoke movements appropriate for escape from or removal of the stimulus applied. Now “feeling” is implicit in the emotional state; the state is an “affective state.” In the evolution of emotion the revival of “feelings” pleasureable and painful must have played a large part. Hence the close relation of emotion with sense-organs that can initiate bodily pain or pleasure, and hence its connection with impulsive or instinctive movement. There is no wide interval between the reflex movement of the spinal dog whose foot attempts to scratch away an irritant applied to its back—both leg and back absolutely detached from consciousness—and the reaction of the decerebrate dog that turns and growls and bites at the fingers holding his hind foot too roughly. In the former case the motor reaction occurs, although the mind is not even aware of the stimulus, far less percipient of it as an irritant. The action occurs, and plays the pantomime of feeling; but no feeling comes to pass. In the latter case the motor reaction occurs and is expressive of emotion; but it is probably the reaction of an organic machine which can be started working, though the mutilation precludes the psychosis.

And with the gesture and the attitude will occur the visceral concomitant. It would be consonant with what we know of reflex action, if the spur that started the muscular expression should simultaneously and of itself initiate also the visceral adjunct reaction. It is almost impossible to believe that with the mere stump of brain that remained to Goltz’s dog there could be any elaboration of a percept. All trace of memory seemed lacking to the creature. Yet though not evincing other emotion, anger it showed as far as expression can yield such revelation. Fear, joy, affection seem, therefore, in the experience of this skilled observer of animal behaviour, to demand higher nervous organization than does anger. Be that as it may, the retention of its expression by Goltz’s dog indicates that by “retrogradation” the complex movement of expression has in certain emotions passed into a simpler reflex-act. Under the canalizing force of habit the determining motives become, even in impulsive acts, weaker and more transient. The external stimulus originally aroused a strongly affective group of ideas, which operated as a motive, but now it causes a discharge of the act before it can be apprehended as an idea. The impulsive movement of a “lower,” “coarser,” so-called “animal” emotion, has in this case become an automatic reflex no longer necessarily combined with the psychical state whence it arose, of which it is normally at once the adjunct and the symbol.

In view of these general considerations and of the above experiments, we may with James accept visceral and organic sensations and the memories and associations of them as contributory to primitive emotions, but we must regard them as reinforcing rather than initiating the psychosis. Organic and vascular reaction, though not the actual excitant of emotion, strengthen it. This is the kernel of the old contention about actuality of emotion in the art of the artist. Hamlet’s description of the actor as really moved by his expression may be accepted as an answer.

Conversely, as Lloyd Morgan^216a writes, “Whatever be the exact psychological nature of the emotions, it may be regarded as certain that they introduce into the conscious situation elements which contribute not a little to the energy of behaviour.” A feeling of pain and a protective reflex movement—either of defence or escape—are concurrent in the reaction of an animal to a hurtful stimulus of the skin. Reflexes to -which emotion is adjunct are not only prepotent (Lect. VI) but are imperative, that is, volition cannot easily suppress them. Now, the morphological disposition of the nervous channels is such that the physiologist can, by suitable severance of the spinal path to the brain, sunder the reflex movement from the sensation, leaving the former effect but perforce annulling the latter. The former is, however, in absence of the latter, not left unaltered; it is abnormally reduced, especially in duration (v. supra, p. 252). The pseudaffective reactions indicative of resentment and defence are, after ablation of the cerebral cortex, short-lived, the simulacra of mere flashes of mimetic passion. No cerebral reverberation descends to prolong and develop further the protective movement set going as a spinal reflex. This contrasts strongly with the fairly normal course that the headward part of the reflex, after loss of its vascular and visceral fields, runs. The difference argues that the reverberation from the trunk, limbs, and viscera counts for relatively little, even in the primitive emotions of the dog, as compared with the cerebral reverberation to which is adjunct the psychical component of emotional reaction.