THE ORGANIC AND THE INORGANIC 321 



ment indicative of a very definite plan which was 

 present in the minds of the players shortly after the 

 game began. 



Mechanistic biology would seek to explain this 

 transformation of a homogeneous system of elements 

 into a heterogeneous and specific arrangement by the 

 interaction of the elements with each other, and by 

 the reaction of the environment. But, given a homo- 

 geneous arrangement of elements capable of interacting 

 with each other, then only one final phase can be 

 supposed to be produced. A mixture of sulphur, 

 carbon dust, copper and iron filings raised suddenly to 

 a high temperature will only interact in one way, and 

 the final phase of the system will depend on the com- 

 position of the mixture, on the temperature, and on 

 the conduction of heat into the mixture in the initial 

 stage of heating. A mixture of chloroform and water 

 shaken up in a bottle is at first a " homogeneous " 

 mixture of the particles of the two substances, but 

 under the influence of gravity the liquids separate 

 from each other and form two distinct layers, each of 

 which will contain in solution some of the other liquid. 

 A homogeneous mixture of different substances there- 

 fore becomes a heterogeneous arrangement in the in- 

 organic system, as in the organic one, but while we can 

 predict the former one we cannot predict the latter. 

 We can express the result of the combination of the 

 elements of the inorganic mixture as something that 

 depends on chemical and physical potentials, but this 

 is quite impossible in the case of the development of 

 the embryonic system. It is not only that our know- 

 ledge of the developmental process is imperfect : the 

 distinction between the two processes of differentiation 

 is a fundamental one. A change in the conditions 

 under which the inorganic system differentiates leads 



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