CHAPTER XIV 



THE DETERMINATION OF THE CRITICAL POINT OF DEATH 

 BY INVERSION OF THE THERMO-MECHANICAL CURVE 



Death-spasm in anisotropic organ due to differential longitudinal contraction — In 

 radial organ the death-contraction is purely longitudinal — Death-point deter- 

 mined from point of inversion of a thermo-mechanical curve — The complete 

 record thus constitutes a curve of life-and-death, the two being separated hy 

 the death-point — Characteristic thermo-mechanical curve as resultant of varia- 

 tion of temperature and variation of length — The necessity of specifying the 

 rate of rise of temperature — Tlie thermo-mechanical curve characterised by 

 sharp and definite inversion at point of death — No inversion of thermo- 

 mechanical curve after death of plant — Death-contraction under heat-rigor in 

 plant analogous to similar phenomenon in animal — The Morograpli, a perfected 

 form of apparatus for determining critical point of death — Remarkable identity 

 of thermo-mechanical curves obtained with two similar specimens — Death-point 

 almost as definite as a physical constant — Vanishing of point of inversion with 

 age — Determination of death-point under cold-rigor — Constancy of death-point. 



We have seen how the death-point can be determined in 

 anisotropic organs, by the occurrence of a spasmodic lateral 

 movement. We have also seen that this death- movement is 

 an excitatory response, at once initiated and terminated at 

 the point of death. It has been shown further that the 

 anisotropic is simply an instance of differential longitudinal 

 response. It follows that if the death-spasm in the aniso- 

 tropic organ be indeed caused by true excitation, then from 

 a radial organ, at the moment of death, we should obtain a 

 purely longitudinal contraction. We may look upon this phe- 

 nomenon, again, from a purely molecular standpoint. We can 

 then see that if death be brought about by a sudden mole- 

 cular change, such an event might be expected to exhibit 

 itself in a correspondingly sudden change of form. Let us 



