DEVELOPMENT 217 



there are potentialities in the physical sense. These act so that 

 their results appear to us as things (blastomeres, etc.) physically 

 extended. 



We have not been inclined to think about space otherwise than 

 as something indifferent. It is true that the tide-generating force 

 of the moon on the ocean is proportional to the square of the 

 distance of the moon, but we look upon this force as " exerted " 

 by the mass of the moon. But it would appear that what any 

 blastomere, or small mass of cells in an embryogeny, is going 

 to become depends on its spatial relationship to other blastomeres, 

 or cells. Thus the epidermal cells opposite to the developing 

 optic cup become the crystalline lens of the eye and the adjacent 

 epidermal cells remain epidermis. But if the optic cup is " trans- 

 planted " the opposite cells in the new region of epidermis 

 (which otherwise would have remained epidermal) now become 

 crystalline lens. At present it is in keeping with modern specula- 

 tion to say that the cells of the optic cup secrete enzymes which 

 so act on the adjacent epidermal cells as to cause them to become 

 a lens — obviously this is only speculation. 



And in recent physics space has acquired positive quality, or 

 properties. This, of course, is only mathematical speculation, 

 still it is suggestive of a corresponding outlook upon developmental 

 problems. 



vii. The developmental organization can be indefinitely sub- 

 divided and still remain what it was. 



Thus a cod-egg may become an adult fish which spawns several 

 millions of eggs and each of the latter may again become a cod 

 and reproduce several millions of eggs and so on without limit. 

 In such a case we must think about the original " single " organiza- 

 tion as being divided into millions of parts and of each '' part " 

 being again similarly divided and so on. In all these " parts " 

 the original organization is present. There is no limit, because 

 though evolution means a change in the organization (so that 

 a new species of Gadiis comes into existence) there need not be 

 any evolutionary process. There is no physical analogy to this. 

 In all energies there are quanta, or minimal limits to subdivision. 

 We cannot clearly think about the organization as suffering 

 diminution by subdivision and then growing again, for it is not 

 a material-energetic entity (though it implies energy). It has 

 been suggested that there is a physical analogy given by fragment- 



