GENESIS, HEREDITY, AND VARIATION. 337 



still left unanswered the question — why docs gamogcnesis 

 recur? And to this tlie reply suggested was, that the ap- 

 proach towards general equilibrium in organisms, " is ac- 

 companied by an approach towards molecular equilibrium in 

 them; and that the need for this union of sperm-cell with 

 germ-cell is the need for overthrowing this equilibrium, and 

 re-establishing active molecular change in the detached germ 

 — a result probably effected by mixing the slightly-different 

 physiological units of slightly-different individuals." This is 

 the hypothesis which we have now to consider. Let us first 

 look at the evidences which certain inorganic phenomena 

 furnish. 



The molecules of any aggregate which have not a balanced 

 arrangement, inevitably tend towards a balanced arrangement. 

 As before mentioned (First Principles, § 100), amorphous 

 wrought iron, when subject to continuous jar, begins to arrange 

 itself into crystals — its atoms assume a condition of polar 

 equilibrium. The particles of unannealed glass, which are so 

 unstably arranged that slight disturbing forces make them 

 separate into small groups, take advantage of that greater 

 freedom of movement given by a raised temperature, to ad- 

 just themselves into a state of relative rest. During any 

 such re-arrangement the aggregate exercises a coercive force 

 over its units. Just as in a growing crystal the atoms suc- 

 cessively assimilated from the solution, are made by the 

 already crystallized atoms to take a certain form, and even to 

 re-complete that form when it is broken; so in any mass of 

 unstably-arranged atoms which passes into a stable arrange- 

 ment, each atom conforms to the forces exercised on it by all 

 the other atoms. This is a corollary from the general law of 

 equilibration. We saw (First Principles, § 170) that every 

 change is towards equilibrium; and that change can never 

 cease until equilibrium is reached. Organisms, above 



all other aggregates, conspicuously display this progressive 

 equilibration; because their units are of such kinds, and sa 

 conditioned, as to admit of easy re-arrangement. Those 



