Response in the Living and Non-Living

seatgs a a ee ee ee ee See Se ee tk ee fee a eee eee Set er a ew = SRS gon pire pe ee Sete . so eas = 7? Oe = . - a —_ - -- = paoe . paca m: 2 segameartsent Saar” orn Fe Nn a tal od tl et et te i ot Se ee, ee - - — “a I HAve in the present work put in a connected and a more complete form results, some of which have been ‘De la Généralité des Phénoménes Moleculaires produits par l’Electricité sur la matiere Inorganique et sur la matiere Vivante.” (Travaux du Congres International de Physique. Paris, 1900.)

‘On the Similarity of Effect of Electrical Stimulus on In- organic and Living Substances.’ (Report, Bradford Meeting British Association, 1900.—Electrician.) ‘Response of Inorganic Matter to Stimulus.’ (Friday Evening Discourse, Royal Institution, May 1901.) ‘On Electric Response of Inorganic Substances. Preliminary Notice.’ (Royal Society, June 1901.) ‘On Electric Response of Ordinary Plants under Me- chanical Stimulus.’ (Journal Linnean Society, 1902.)

‘Sur la Réponse Electrique dans les Métaux, les Tissus Animaux et Végétaux.’ (Société de Physique, Paris, ‘On the Electro-Motive Wave accompanying Mechanical Disturbance in Metals in contact with Electrolyte.’ (Proceedings Royal Society, vol. 70.) ‘On the Strain Theory of Vision and of Photographic Action.’ (Journal Royal Photographic Society, vol. xxv1.) These investigations were commenced in India, and I take this opportunity to express my grateful acknowledgements to the Managers of the Royal Institution, for the facilities offered me to complete them at the Davy-Faraday Laboratory.

Davy-Farapay LAsoratory, Royau INstituTion, Lonnon: May 1902. Mechanical response—Different kinds of stimuli—Myograph—Characteristics of response-curve: period, amplitude, form—Modification of response-curves 2 : : - ; : : : i) Conditions for obtaining electric response—Method of injury—Current of injury—Injured end, cuproid: uninjured, zincoid—Current of response in nerve from more excited to less excited—Difficulties of present nomenclature—Electric recorder—Two types of response, positive and negative—Universal applicability of electric mode of response—Electric response a measure of physiological activity— Electric response in plants. ; : ; : : : : 5

Negative variation — Response recorder — Photographic recorder— Compensator— Means of graduating intensity of stimulus—Springtapper and torsional vibrator—Intensity of stimulus dependent on amplitude of vibration—Effectiveness of stimulus dependent on rapidity also. : : : : . ; , : : at ae Method of block—Advantages of block method—Plant response a physiological phenomenon—Abolition of response by anzesthetics Abolition of response when plant is killed by hot

Effect of single stimulus—Superposition of stimuli—A dditive effeet— Staircase effect—Fatigue—No fatigue when sufficient interval between stimuli—Apparent fatigue when stimulation frequency is increased—Fatigue under continuous stimulation 2 : Diphasic variation—Positive after-effect and positive response—Radial Increased response with increasing stimulus—Apparent diminution of response with excessively strong stimulus . ; «) set Effect of very low temperature—Influence of high temperature— Determination of death-point —Increased response as after-effect of temperature variation—Death of plant and abolition of response

by the action of steam . 59 Effect of anzsthetics, a test of vital character of response—EKffect of chloroform—Effect of chloral—Effect of formalin—Method in which response is unaffected by variation-of resistance—Advantage of block method—FEffect of dose . el Is response found in inorganic substances?—Experiment on tin, block method—Anomalies of existing terminology—Response by method , 5 tel Conditions of obtaining quantitative measurements—Modification of the block method—Vibration cell—Application of stimulus— Graduation of the intensity of stimulus—Considerations showing that electric response is due to molecular disturbance—Test experi-

Effects of molecular inertia—Prolongation of period of recovery by overstrain—Molecular model—Reduction of molecular sluggishness attended by quickened recovery and heightened response— Effect of temperature—Modification of latent period and period of recovery by the action of chemical reagents—Diphasic variation . 104 Fatigue in metals —Fatigue under continuous stimulation—Staircase effect—Reversed responses due to molecular modification in nerve and in metal, and their transformation into normal after continuous stimulation—Increased response after continuous stimulation oe JS

Relation between stimulus and response—Magnetic analogue—In- crease of response with increasing stimulus—Threshold of response —Superposition of stimuli— Hysteresis ; A é : = Action of chemical reagents—Action of stimulants on metals—Action of depressants on metals—Effect of ‘ poisons ’ on metals—Opposite effect of large and small doses Visual impulse : (1) chemical theory; (2) electrical theory—Retinal currents—Normal response positive—Inorganic response under stimulus of light—Typical experiment on the electrical effect in-

Effect of temperature—Effect of increasing length of exposure—Relation between intensity of light and magnitude of response—A< fteroscillation—Abnormal effects: (1) preliminary negative twitch; (2) reversal of response ; (3) transient positive twitch on cessation of light ; (4) decline and reversal—Résumé | Effect of light of short duration—A fter-oscillation—Positive and negative after-images— Binocular alternation of vision—Period of alter-

nation modified by physical condition—After-images and their revival— Unconscious visual impression MecuHanicaL Lever RECORDER f 3 : ; ; : 3 Exectric MrerHop oF Detecting NERVE RESPONSE a ee 6 DIAGRAM SHOWING INJURED END oF NERVE CORRESPONDS TO Copper IN A VOLTAIC ELEMENT : : : : : 8 Eecrric RECORDER . ; : ‘ : : : te al SimuLtaNgous Record oF MECHANICAL AND ELECTRICAL RESPONSES . : : F . E : : : » ws NEGATIVE VARIATION IN PLANTS ; : : ; Pa ie yee i!)

Response RECORDER ‘ ; Brags é : : a BAL THE COMPENSATOR. i ; : : ? : Siro ae Tue Torsional VIBRATOR. : ‘ : ; : ee go! RESPONSE IN PLANT TO MecHanicaL TAP OR VIBRATION . 25 Tue Meruop or Broce. 5 ; : : Zé ; 2 28 UnirormM RESPONSES IN PLANT : ; ; ; tJ FOO AppitivE EFFECT oF SINGLY INEFFECTIVE STIMULI ON Pranr . ; 4 : d : A : E aoe 37 Vie, PAGE 21. Farievp In CELERY 4O 22, FaticguE IN CAULIFLOWER-STALK 5 , : : 41 93, FaricuB FROM PREVIOUS OVERSERAIN 41 24, Farigurz UNDER CONTINUOUS STIMULATION IN CELERY 42, 95. Errecr or Rest 1n REMOVAL OF FATIGUE IN PLANT . 43 96. DIPpHASIC VARIATION IN PLANT. 46 27,28. ABNORMAL PosttIvE RESPONSES IN STALE PLANT TRANS- FORMED INTO NoRMAL NEGATIVE UNDER STRONG STIMU- 29. RapiaL E.M. VARIATION 50 STIMULUS AND Response IN MuscLE AND NERVE 52 31. Increasinc Responses To IncREASING StiMuLI (TAPS) IN IN PLANTS . : : j ; ; ‘ : 53 35. Diminutrion oF Response IN EvcHaris Lity at Low TEm- 36. RECORDS SHOWING THE DIFFERENCE IN THE EFFECTS oF Low TEMPERATURE ON Ivy, Hotty, anp Eucnaris Lity . 62 37. Prant CHAMBER FOR STUDYING THE EFFECT oF TEMPERA- 38. Errecr or High TEMPERATURE ON PLANT RESPONSE 64 VARIATION ; : é ; ; 5 ; 66 40. Recorps or Responses IN Eucuaris Lity DuRING RIsE AND Fatt oF TEMPERATURE ; : , 2 : : 2 nitolt CyYcLe oF TEMPERATURE VARIATION , F ; U3 Gs 42, Recorp or Errecrt or Steam IN ABOLITION OF RESPONSE At DEATH OF PLANT . : : , . : : . “469

TLLOSTRATLTIONS xV11 Errect or CHLOROFORM ON NERVE RESPONSE . he Errect oF CHLOROFORM ON THE RESPONSES OF CARROT fal Acrion oF CHLORAL HypRAtTE ON PLANT RESPONSES eno Action oF FoRMALIN ON RADISH . ; 3 75 Acrion or Sopium HypRrarre IN ABOLISHING THE RESPONSE SrrmuLatine Action oF Potson IN SMALL Doses IN Piants 79 Tus Porsonous Errect oF SrronceR Dose or KOH . 79 Brock MErHoD FOR OBTAINING RESPONSE IN TIN 83 Response TO MECHANICAL STIMULATION IN A ZN-Cu CovuPLE 85 Enecrric Response IN Meran BY THE MerHop oF RELA- TIVE DEPRESSION (NEGATIVE VARIATION) . : j 5 fete) Metruop oF RELATIVE EXALTATION . d : 89 Various Casss oF PositIvE AND NEGATIVE VARIATION 90 MopIFICATIONS OF THE Biock MerrHop FOR EXHIBITING Erecrric Response IN Merats 93 EquAL AND Opposite RESPONSES: GIVEN BY Two ENDs oF Top VIEW OF THE VIBRATION CELL. : : , ; 96 Response IN METALS . 101 Untrrorm Execrric Responses 1N METALS 102 PROLONGATION OF PERIOD OF RECOVERY AFTER OveRsTRAIN 106 MoxtecutaR MoprrL . ‘ 2 F : ; : 107 64. Errects oF ReEeMovAL oF MOLECULAR SLUGGISHNESS IN QUICKENED RecoveRY AND HEIGHTENED RESPONSE IN EFrect oF TEMPERATURE ON RESPONSE IN METALS. Ui DrpHasic VARIATION IN METALS NS

Continuous TRANSFORMATION FROM NEGATIVE TO POSITIVE THROUGH INTERMEDIATE DIpHAsic RESPONSE . ° . Faticurt In MuscLeE . : Fatigue IN PLATINUM FavticteE in Tin. FAatiguE IN Mrrat UNDER Continuous STIMULATION ‘SrarrcAse’ Response In Musche AND IN Mera Into NORMAL UNDER CONTINUED STIMULATION - ? IN PLATINUM . : 5 ; , : p : ae Acrion oF Porson IN ABOLISHING RespoNSE IN NERVE . ACTION OF STIMULANT on TIN ABOLITION OF RESPONSE IN METALS By ‘ POISON ’ ‘MoLecuLaR ARREST’ BY THE ACTION OF ‘PoISON’ . :

Opposite Errecrs’ oF SMALL AND LARGE DosEs ON THE Response In Mevats TypicAL EXPERIMENT ON THE E.M. Variation PRopUCED BY LicgHT . : : : ; ; : : : RESPONSES OF SENSITIVE CELL to IncREASING INTENSITIES oF LicHT . ; : , E - 2 e TRANSIENT PostriveE INCREASE oF RESPONSE IN THE F ROG’s RETINA ON THE CESSATION OF LicHT TRANSIENT PositTIvE INCREASE OF RESPONSE IN THE SENSITIVE CELL . , : ; See ; DECLINE UNDER THE ContTINUOUS Action oF LicHutT AFTER-EFFECT OF Ligut oF SHORT DURATION .

Untrorm Responses IN NERVE, PLant, AND Meran Fatiegv& In Muscie, PLant, anD METAL ‘SrarroasE’ Errect in Muscie, PLrant, AND MerTAL Mopirtep AspnorMAL Response IN NERVE AND MeErar TRANSFORMED INTO NokMAL RESPONSE AFTER CONTINUOUS Mechanical response —Different kinds of stimuli—Myograph—Characteristics of response-curve: period, amplitude, form — Modification of response-curves. OnE of the most striking effects of external disturbance on certain types of living substance is a visible change of form. Thus, a piece of muscle when pinched contracts. The external disturbance which produced this change is called the stimulus. The body which is thus capable of responding is said to be irritable or excitable. A stimulus thus produces a state of excitability which may sometimes be expressed by change of form.

Mechanical response to different kinds of stimuli.— This reaction under stimulus is seen even in the lowest organisms; in some of the ameeboid rhizopods, for instance. These lumpy protoplasmic bodies, usually elongated while creeping, if mechanically jarred, contract into a spherical form. If, instead of mechanical disturbance, we apply salt solution, they again contract, in the same way as before. Similar effects are produced by sudden illumination, or by rise of temperature, or by electric shock. A living substance may thus be put into an excitatory state by either mechanical, chemical, thermal, electrical, or heht stimulus. Not only does the point stimulated show the effect of stimulus, but that effect may sometimes be conducted even to a considerable distance. This power of conducting stimulus, though common to all living substances, is present in very different degrees. While in some forms of animal tissue irritation spreads, at a very slow rate, only to points in close neighbourhood, in other forms, as for example in nerves, conduction is very rapid and reaches far.

The visible mode of response by change of form may perhaps be best studied in a piece of muscle. When this is pinched, or an electrical shock is sent through it, it becomes shorter and broader. A responsive twitch is thus produced. The excitatory state then disappears, and the muscle is seen to relax into its normal form. Mechanical lever recorder.—In the case of contraction of muscle, the effect is very quick, the twitch takes place in too short a time for detailed observation by ordinary means. A myographic apparatus is therefore used, by means of which the changes in the muscle are self-recorded. Thus we obtain a history of its change and recovery from the change. The muscle is connected to one end of a writing lever. When the muscle contracts, the tracing point is pulled up im one

direction, say to the right. depends on the amount of contraction. The extent of this pull A band of paper or a revolving drum-surface moves at a uniform speed at right angles to the direction of motion of the writing lever. When the muscle recovers from the stimulus, it relaxes into its origmal form, and the writing point traces the recovery as it moves now to the left, regaining its first position. A curve is thus described, the risimg portion of which is due to contraction, and the falling portion to relaxation

Characteristics of the responsecurve: (I) Period, (2) Amplitude, (3) Form.—Just as a wave of sound is characterised by its (1) period, (2) amplitude, and (3) form, so may these response-curves be distinguished from each other. As regards the period, there is an bone is securely held at one end, the other end being connected with the writing lever. Under the action of stimulus the contracting muscle pulls the lever and moves the tracing point to the right over the travelling recording surface P. When the muscle recovers from contraction, the tracing pointreturns to its original position. See on P the record of muscle curve.

enormous variation, corresponding to the functional activity of the muscle. For instance, in tortoise it may be as high as a second, whereas in the wing-muscles of many insects it is as small as 51, ‘It is probable that a continuous graduated scale might, as suggested by Hermann, be drawn up in the animal kingdom, from the excessively rapid contraction of Differences in form and amplitude of curve are well illustrated by various muscles of the tortoise. The curve for the muscle of the neck, used for rapid withdrawal of the head on approach of danger, is quite different from that of the pectoral muscle of the same animal, used for its sluggish movements.

Again, progressive changes in the same muscle are well seen in the modifications of form which consecutive muscle-curves gradually undergo. In a dying muscle, for example, the amplitude of succeeding curves is continuously diminished, and the curves themselves are elongated. Numerous illustrations will be seen later, of the effect, in changing the form of the curve, of the increased excitation or depression produced by various agencies. Thus these response records give us a means of studying the effect of stimulus, and the modification of response, under varying external conditions, advantage being taken of the mechanical contraction produced in the tissue by the stimulus. But there are other kinds of tissue where the excitation produced by stimulus is not exhibited in avisible form. In order to study these we have to use an altogether independent method, the method of electric response.

Conditions for obtaining electric response— Method of injury —Current of injury—Injured end, cuproid: uninjured, zincoid—Current of response in nerve from more excited to less excited—Difficulties of present nomenclature—Electric recorder—T wo types of response, positive and negative —Universal applicability of electric mode of response—Electric response a measure of physiological activity—Electric response in plants. UNLIKE muscle, a length of nerve, when mechanically or electrically excited, does not undergo any visible change. That it is thrown into an excitatory state, and that it conducts the excitatory disturbance, is shown however by the contraction produced in an attached piece of muscle, which serves as an indicator.

But the excitatory effect produced in the nerve by stimulus can also be detected by an electrical method. If an isolated piece of nerve be taken and two contacts be made on its surface by means of non-polarisable electrodes at A and B, connection being made with a galvanometer, no current will be observed, as both A and B are in the same physico-chemical condition. The two points, that is to say, are iso-electric. If now the nerve be excited by stimulus, similar disturbances will be evoked at both A and B. If, further, these disturbances, reaching A and B almost simultaneously, cause any electrical change, then,

similar changes taking place at both points, and there being thus no relative difference between the two, the galvanometer will still indicate no current. This nulleffect is due to the balancing action of B as against A. (See fig. 2, a.) Conditions for obtaining electric response.—If then we wish to detect the response by means of the galvanometer, one means of doing so will lie in the abolition of » this balance, which may be accomplished by making one of the two points, say B, more or less permanently

(6) The end B injured; current of injury from B to A: stimulation gives rise to an action current from A to B. irresponsive. In that case, stimulus will cause greater electrical disturbance at the more responsive point, say A, and this will be shown by the galvanometer as a current of response. To make B less responsive we may injure it by means of a cross-sectional cut, a burn, or the action of strong chemical reagents. Current of injury.—We shall revert to the subject of electric response; meanwhile it is necessary to say a few words regarding the electric disturbance caused by the injury itself. Since the physico-chemical conditions of the uninjured A and the injured B are now no longer the same, it follows

that their electric conditions have also become different. They are no longer iso-electric. There is thus a more or less permanent or resting difference of electric potential between them. A current—the current of injury—is found to flow in the nerve, from the injured to the uninjured, and in the galvanometer, through the electrolytic contacts from the uninjured to the injured. As long as there is no further disturbance this current of injury remains approximately constant, and is therefore sometimes known as ‘the current of rest’ (fig. 2, b).

A piece of living tissue, unequally injured at the two ends, is thus seen to act like a voltaic element, comparable to a copper and zinc couple. As some confusion has arisen, on the question of whether the injured end is like the zine or copper in such a combination, it will perhaps be well to enter upon this subject in detail. If we take two rods, of zine and copper respectively, in metallic contact, and further, if the points A and B are connected by a strip of cloth s moistened with salt solution, it will be seen that we have a complete voltaic element. A current will now flow from B to A in the metal (fig. 8, a) and from A to B through the electrolyte s. Or instead of connecting Aand B by a single strip of cloth s, we may connect them by two strips s s’, leading to non-polarisable electrodes EE’. The current will then be found just the same as before, i.e. from B to A in the metallic part, and from A through s s’ to B, the wire W being interposed, as it were, in the electrolytic part of the circuit. If now a galvanometer be interposed at 0, the current will flow from B to A through the galvanometer, i.e. from right to left. But if we interpose the galvanometer in the electrolytic part of the circuit, that is to say, at W, the same current will appear to flow in the opposite direction. In fig. 3, c, the galvanometer is so interposed, and in this case it is to be noticed that when the current in the galvanometer flows from left to right, the metal connected to the left is zine.

Compare fig. 3, d, where A B is a piece of nerve of which the B end is injured. The current in the galvanometer through the non-polarisable electrode is from left to right. The uninjured end is therefore comparable to the zinc in a voltaic cell (is zincoid), the injured being copper-like or cuproid.! If the electrical condition of, say, zinc in the voltaic couple (fig. 8, c) undergo any change (and I shall show later that this can be caused by molecular disturbance), then the existing difference of potential between A and B will also undergo variation. If for example the electrical condition of A approach that of B, the potential difference will undergo a

Fic. 3.—DIAGRAM SHOWING THE CORRESPONDENCE BETWEEN INJURED (B) AND UNINJURED (A) conTacts IN NERVE, AnD Cu anp Zn 1n A Vottaic ELEMENT Comparison of (c) and (d) will show that the injured end of B in (d) corresponds with the Cu in (c). diminution, and the current hitherto flowing in the circuit will, as a consequence, display a diminution, or negative variation. Action current—We have seen that a current of injury—sometimes known as ‘current of rest —flows in a nerve from the injured to the uninjured, and that the injured B is then less excitable than the uninjured A. If now the nerve be excited, there being a greater