ILLUSTRATIONS

FIG.PAGE
[1].Mechanical Lever Recorder[3]
[2].Electric Method of Detecting Nerve Response[6]
[3].Diagram showing Injured End of Nerve Corresponds to Copper in a Voltaic Element[8]
[4].Electric Recorder[11]
[5].Simultaneous Record of Mechanical and Electrical Responses[13]
[6].Negative Variation in Plants[19]
[7].Photographic Record of Negative Variation in Plants[20]
[8].Response Recorder[21]
[9].The Compensator[22]
[10].The Spring-tapper[23]
[11].The Torsional Vibrator[24]
[12].Response in Plant to Mechanical Tap or Vibration[25]
[13].Influence of Suddenness on the Efficiency of Stimulus[26]
[14].The Method of Block[28]
[15].Response in Plant completely Immersed under Water[29]
[16].Uniform Responses in Plant[36]
[17].Fusion of Effect under Rapidly Succeeding Stimuli in Muscle and in Plant[36]
[18].Additive Effect of Singly Ineffective Stimuli on Plant[37]
[19].‘Staircase Effect’ in Plant[37]
[20].Appearance of Fatigue in Plant under Shortened Period of Rest[39]
[21].Fatigue in Celery[40]
[22].Fatigue in Cauliflower-stalk[41]
[23].Fatigue from Previous Overstrain[41]
[24].Fatigue under Continuous Stimulation in Celery[42]
[25].Effect of Rest in Removal of Fatigue in Plant[43]
[26].Diphasic Variation in Plant[46]
[27], [28].Abnormal Positive Responses in Stale Plant transformed into Normal Negative Under Strong Stimulation[48], [49]
[29].Radial E.M. Variation[50]
[30].Curves showing the Relation between Intensity of Stimulus and Response in Muscle and Nerve[52]
[31].Increasing Responses to Increasing Stimuli (Taps) in Plants[52]
[32].Increasing Responses to Increasing Vibrational Stimuli in Plants[53]
[33].Responses to Increasing Stimuli in Fresh and Stale Specimens of Plants[54]
[34].Apparent Diminution of Response caused by Fatigue under Strong Stimulation[57]
[35].Diminution of Response in Eucharis Lily at Low Temperature[61]
[36].Records showing the Difference in the Effects of Low Temperature on Ivy, Holly, and Eucharis Lily[62]
[37].Plant Chamber for Studying the Effect of Temperature and Anæsthetics[64]
[38].Effect of High Temperature on Plant Response[64]
[39].After-effect on the Response due to Temperature Variation[66]
[40].Records of Responses in Eucharis Lily during Rise and Fall of Temperature[67]
[41].Curve showing Variation of Sensitiveness during a Cycle of Temperature Variation[68]
[42].Record of Effect of Steam in Abolition of Response at Death of Plant[69]
[43].Effect of Chloroform on Nerve Response[72]
[44].Effect of Chloroform on the Responses of Carrot[74]
[45].Action of Chloral Hydrate on Plant Responses[75]
[46].Action of Formalin on Radish[75]
[47].Action of Sodium Hydrate in Abolishing the Response in Plant[78]
[48].Stimulating Action of Poison in Small Doses in Plants[79]
[49].The Poisonous Effect of Stronger Dose of KOH[79]
[50].Block Method for obtaining Response in Tin[83]
[51].Response To Mechanical Stimulation in a Zn-Cu Couple[85]
[52].Electric Response in Metal by the Method of Relative Depression (Negative Variation)[88]
[53].Method of Relative Exaltation[89]
[54].Various Cases of Positive and Negative Variation[90]
[55].Modifications of the Block Method for Exhibiting Electric Response in Metals[93]
[56].Equal and Opposite Responses given by Two Ends of the Wire[95]
[57].Top View of the Vibration Cell[96]
[58].Influence of Annealing in the Enhancement of Response in Metals[101]
[59].Uniform Electric Responses in Metals[102]
[60].Persistence of After-effect[105]
[61].Prolongation of Period of Recovery after Overstrain[106]
[62].Molecular Model[107]
[63], [64].Effects of Removal of Molecular Sluggishness in Quickened Recovery and Heightened Response in Metals[109], [110]
[65].Effect of Temperature on Response in Metals[111]
[66].Diphasic Variation in Metals[113]
[67].Negative, Diphasic, and Positive Resultant Response in Metals[115]
[68].Continuous Transformation from Negative to Positive through Intermediate Diphasic Response[116]
[69].Fatigue in Muscle[118]
[70].Fatigue in Platinum[118]
[71].Fatigue in Tin[119]
[72].Appearance of Fatigue due to Shortening the Period of Recovery[120]
[73].Fatigue in Metal under Continuous Stimulation[121]
[74].‘Staircase’ Response in Muscle and in Metal[122]
[75].Abnormal Response in Nerve converted into Normal under Continued Stimulation[124]
[76], [77].Abnormal Response in Tin and Platinum converted into Normal under Continued Stimulation[125]
[78].Gradual Transition from Abnormal to Normal Response in Platinum[126]
[79].Increase of Response in Nerve after Continuous Stimulation[127]
[80], [81].Response in Tin and Platinum Enhanced after Continuous Stimulation[127], [128]
[82].Magnetic Analogue[132]
[83], [84].Records of Responses to Increasing Stimuli in Tin[134], [135]
[85].Ineffective Stimulus becoming Effective by Superposition[135]
[86].Incomplete and Complete Fusion of Effects[136]
[87].Cyclic Curve for Maximum Effects showing Hysteresis[137]
[88].Action of Poison in Abolishing Response in Nerve[139]
[89].Action of Stimulant on Tin[141]
[90].Action of Stimulant on Platinum[142]
[91].Depressing Effect of KBr on Tin[143]
[92].Abolition of Response in Metals by ‘Poison’[143]
[93].‘Molecular Arrest’ by the Action of ‘Poison’[145]
[94].Opposite Effects of Small and Large Doses on the Response in Metals[146]
[95].Retinal Response to Light[150]
[96].Response of Sensitive Cell to Light[152]
[97].Typical Experiment on the E.M. Variation Produced by Light[154]
[98].Modification of the Photo-sensitive Cell[155]
[99].Responses in Frog’s Retina[156]
[100].Responses in Sensitive Photo-cell[157]
[101].Effect of Temperature on the Response to Light Stimulus[159]
[102].Effect of Duration of Exposure on the Response[159]
[103].Responses of Sensitive Cell to Increasing Intensities of Light[161]
[104].Relation between the Intensity of Light And Magnitude of Response[162]
[105].After-oscillation[163]
[106].Transient Positive Increase of Response in the Frog’s Retina on the Cessation of Light[164]
[107].Transient Positive Increase of Response in the Sensitive Cell[165]
[108].Decline under the Continuous Action of Light[166]
[109].Certain After-effects of Light[168]
[110].After-effect of Light of Short Duration[172]
[111].Stereoscopic Design for the Exhibition of Binocular Alternation of Vision[176]
[112].Uniform Responses in Nerve, Plant, and Metal[184]
[113].Fatigue in Muscle, Plant, and Metal[185]
[114].‘Staircase’ Effect in Muscle, Plant, and Metal[186]
[115].Increase of Response after Continuous Stimulation in Nerve and Metal[186]
[116].Modified Abnormal Response in Nerve and Metal Transformed into Normal Response after Continuous Stimulation[187]
[117].Action of the same ‘Poison’ in the Abolition of Response in Nerve, Plant, and Metal[189]

RESPONSE
IN THE
LIVING AND NON-LIVING

CHAPTER I
THE MECHANICAL RESPONSE OF LIVING SUBSTANCES

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 amœboid 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 light 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.