THE ORIGIN OF LIFE 163 



process is rigidly dependent upon the administration thereto 

 of external energy, which in the process of absorption must 

 of necessity fall from a higher level of intensity. And when 

 the energy thus absorbed by the complex molecule is again 

 set free by combustion, it is degraded to a still lower po- 

 tential, from which, without external intervention, it can never 

 rise again to its former plane of intensity. The phenomena 

 of radioactivity tell the same tale. All the heavier atoms, 

 at least, are constantly disintegrating with a concomitant 

 discharge of energy. There is no compensating process, how- 

 ever, enabling such an atom to re-integrate and recharge itself 

 at stated intervals ; and, once it has broken down into its com- 

 ponent protons and electrons, ''not all the king's horses nor 

 all the king's men can ever put Humpty-Dumpty together 

 again." In a word, none of the inorganic units of the mineral 

 world exhibits that wonderful power of autonomous recupera- 

 tion which a unicellular ciliate manifests when it rejuvenates 

 itself by means of endomixis. The inorganic world knows 

 of no constructive process comparable to this. It is only in 

 living beings that we find what James Ward describes as the 

 "tendency to disturb existing equilibria, to reverse the dissi- 

 pative processes which prevail throughout the inanimate 

 world, to store and build up where they are ever scattering 

 and pulling down, the tendency to conserve individual ex- 

 istence against antagonistic forces, to grow and to progress, 

 not inertly taking the easier way but seemingly striving for 

 the best, retaining every vantage secured, and working for 

 new ones." ("On the Conservation of Energy," I, p. 285.) 

 Summing up, then, we have seen that the reproductive 

 process, whereby the metists or multicellular organism origi- 

 nate, resolves itself ultimately into a process of cell-division. 

 The same is true of the protists or unicellular organisms. For 

 all cells, whether they be protists, germ cells, or somatic cells, 

 originate in but one way, and that is, from a preexistent liv- 

 ing cell by means of cell-division. Neither experimentation 



