Mentality and Self-Consciousness 83 



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stantly changing electrical conditions in the re- 

 gions between the adjacent atoms. 



The responsiveness of living matter to the 

 activities of individual atoms can be readily 

 demonstrated by certain optical experiments. 

 After determining the maximum distance from 

 which a small white object can be seen by the light 

 from a candle-flame, and knowing the size of the 

 pupil of the eye, we can calculate the minimum 

 intensity of light to which the eye is sensitive. 

 Since the radiant energy from one candle-power 

 which falls within the limits of the visible spec- 

 trum amounts to about 190,000 ergs per second, 

 the minimum amount of light-energy per one- 

 fifteenth of a second to which the eye is sensitive 

 can then be calculated. It will be found to be not 

 much greater than 10~ 12 erg, which is approxi- 

 mately the amount of energy required to eject one 

 electron from an atom. 



All natural processes which do not involve the 

 activities of living matter may be classified as 

 reversible and irreversible. Keversible processes 

 are those which are governed by the primary laws 

 of nature. They will proceed equally well in either 

 direction and will not change the entropy of the 

 system. Irreversible processes are those which 

 are governed by the second law of thermody- 



