XIV COMPARATIVE ELECTRO-PHYSIOLOGY 



PAGE 



recorder Uniform electric responses List of suitable specimens 

 Effect of season on excitability Stimulation by thermal shocks Thermal 

 stimulator Second method of confining excitation to one contact In- 

 creasing response to increasing stimulus Effect of fatigue Tetanus . 29 



CHAPTER IV 



OBSERVATION BY RHEOTOME ON ELECTRIC RESPONSE IN 

 PLANTS 



Response-curve showing general time-relations Instantaneous mechanical 

 stimulation by electro-magnetic release Arrangement of the rheotome 

 Tabular statement of results of rheotomic observations Rhythmic 

 multiple responses . . . . , ......... " . 44 



CHAPTER V 



THE ELECTRICAL INDICATIONS OF POSITIVE AND NEGATIVE 

 TURGIDITY-VARIATIONS 



Motile responses of opposite signs, characteristic of positive and negative 

 turgidity-variations - Indirect hydrostatic effect of stimulus causes 

 expansion and erection of leafPositive and negative work Wave of 

 increased hydrostatic tension transmitted with relatively greater velocity 

 than wave of true excitation Method of separating hydro-positive and 

 excitatory effects Indirect effect of stimulus, causing positive turgidity- 

 variation induces galvanometric positivity Antagonistic elements in the 

 electrical response Separation of hydro-positive from true excitatory 

 effect by means of physiological block . . . . . . 



CHAPTER VI 



EXTERNAL STIMULUS AND INTERNAL ENERGY 



Hydraulic transmission of energy in plants True meaning of tonic condi- 

 tionOpposite expressions of internal energy and external stimulus 

 seen in growth-response Parallelism between responses of growing and 

 motile organs Increased internal energy caused by augmentation 01 

 temperature finds expression in enhanced rate of growth ; erection of 

 motile leaf ; curling movement of spiral tendril ; and galvanometric 

 positivity External stimulus induces opposite effect in all these cases- 

 Sudden variation of temperature, acting as a stimulus, induces transient 

 retardation of growth ; depression of motile leaf ; uncurling movement 

 of spiral tendril ; and galvanometric negativity Laws of mechanical 

 and electrical response 60 



