142 THE ORIGIN OF LIFE 



groups of atoms being witlidrawn and others taking 

 their places. If these atoms and groups of atoms are 

 always of the same kind, and if their substance and 

 exit always take place in the same manner and 

 direction, as must be the case so long as the 

 metabolism of the whole remains unaltered, a certain 

 altering of the particles results, which we must call 

 structure ; although the whole substance is in motion, 

 in a continual flow." 



It is only in this way he supposes that the re- 

 construction of the cell can result when a portion 

 is removed. It must, however, be borne in mind 

 that the same phenomenon of reconstruction of a 

 damaged part can take place in crystals, when 

 metabolism in the sense in which he uses the word 

 does not occur. The structure of the cell does not 

 appear to be a particular state of motion of the meta- 

 bolic flow, it seems to consist of surfaces wherein the 

 molecular aggregation and consequent flow are the 

 same. The larger structures for a time remain un- 

 changed even when the flow has ceased, although the 

 more minute structures may or may not depend upon 

 the flow itself 



The formation of very minute cell structures 

 dependent upon instability in the physical and 

 chemical conditions of the flow is, however, possible 

 when we bear in mind that our ideas of the solid 

 and liquid states have been largely, if not completely, 

 altered by the discovery of what are called liquid 

 crystals, which may give a cellular structure to 

 a substance in the ill-definable state between a 



