CHEMICAL CHARACTERS OF CELL 81 



common to draw comparison between the two, 

 and to point to metabolism as the chief dis- 

 tinction. But while this is the most obvious 

 distinction the more fundamental one remains 

 in the energy relations of the two with the 

 environment. The growth of the crystal is the 

 result of the loss of energy; that of the organ- 

 ism the result of the gain of energy. The 

 crystal represents a last position of stable 

 equilibrium assumed by molecules upon a cer- 

 tain loss of kinetic energy, and the formation 

 of the crystal by evaporisation and concentra- 

 tion of a liquid does not, in its dynamic aspect, 

 differ much from the precipitation of an amor- 

 phous sediment (in a footnote it is stated that 

 6 it appears exceptional for the crystalline 

 configuration to stand higher in the scale of 

 energy than the amorphous '). The organism, 

 on the other hand, represents a more or less 

 unstable condition formed and maintained by 

 inllow of energy ; its formation, indeed, is often 

 attended with a loss of kinetic energy (fixation 

 of carbon in plants), but if so, accompanied by 

 a more than compensatory increase of potential 

 molecular energy." 



Finally, as regards the question of crystallisa- 

 tion, the crystal of any rock can be dissolved 

 and will re-crystallise under suitable conditions, 

 and these two processes can be repeated ad 



F 



