LIFE AND DEATH. 287 



energy concerned is primarily what is usually 

 termed chemical energy, and that every compound 

 entering into the protoplasm carries in a supply 

 of this, available in various ways. 



Death, on the contrary, is the cessation of 

 these rhythmical processes of building up and 

 breaking down of the protoplasm molecules. It 

 does not imply the cessation of chemical changes 

 of other kinds, but that these rhythmical con- 

 structions of the complex and labile protoplasm 

 molecules breaking down on stimulation to bodies 

 partly re-assimilable, partly combustible in respira- 

 tion, and partly excretory, etc., have ceased, and 

 that further chemical changes in the material are 

 thenceforth simpler and different in kind and 

 degree, eventually leading to total disintegration 

 so that no units are left capable of restoring the 

 rhythm. 



If these ideas are correct, we may define 

 Disease as dangerous disturbances in the regularity, 

 or interference with the completeness or range of 

 the molecular activities constituting normal Life 

 i.e. Health and it is evident that every degree 

 of transition may be realised between the two 

 extremes. Now, if we further assume, as I think 

 we must do, that a considerable range or " play " 

 must exist in the molecular activities of the 

 protoplasm constituting life, we obtain a sort of 

 expression of what we mean by limits of variation. 

 The fact that life can go on in a given plant at 

 temperatures between from i-5'' and 3 5-40C., 

 or in lights of different intensity, or within 



