CHAPTER VIII 



DEATH-SPASM IN PLANTS 



Criterion of the death of plant — Abolition of electric response at death — 

 Mechanical spasm of death — Water-bath for uniform rise of tempera- 

 ture — Excitatory effect of sudden cooling or heating — Erection of 

 leaf with rising, and depression of leaf with falling, temperature — 

 Thermo-mechanical inversion at the death-point — Necessity for 

 specification of rate of rise of temperature — Death record of Mimosa — 

 Abolition of response after death-spasm — Constancy of death-point 

 exhibited by different specimens — Death records of Desmodium 

 gyrans and Vicia Fava — Death-spasm in ordinary plants — The electric- 

 spasm of death — Lowering of death-point by fatigue and by poisonous 

 solution. 



A plant may be killed by subjecting it to a certain maxi- 

 mum temperature. The exact moment at which death is 

 initiated is difficult to determine, since there has been found 

 no certain and immediate criterion of death. One method 

 by which the occurrence of death may be determined is 

 by the abolition of that electric response which is characteris- 

 tic of the living condition. A plant as long as it is alive 

 gives in answer to a stimulus an electric response of galvano- 

 metric negativity. On the occurrence of death this parti- 

 cular response disappears. I find that the electric response 

 is abolished when the plant has been subjected for a time 

 to a temperature of about 6o° C. 



If the plant is subjected to a gradual rise of temperature, 

 there would arrive a time when the death-change will 

 begin to occur. In the animal an early symptom of death 

 is the setting in of rigor mortis. We shall find that in plants 

 also a death-spasm, analogous to the death-throe of the 

 animal, occurs at a critical moment. 



In order to obtain an automatic record which would 



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