54 C. U. ARIENS KAPPERS 



and which are mostly indicated by the two centrosomes. So 

 here, too, there are two (sometimes more) simultaneous centers 

 of influence, which play an essential part in the accomplishment 

 of the process. 



Whereas, however, the simultaneous action of influences causes 

 a 'linking/ an association in the construction of mental life and 

 also of the nervous system, there appears a differentiation in the 

 other case (in somatic development), a differentiation which, how- 

 ever, remains a unit, an individual; in other words, the 'linking' 

 of the parts which is a consequence of the process in mental life, 

 is present at the starting-point in somatic development and 

 persists. 



Speaking properly, however, it may be said, that here, too, the 

 'linking' of the results of those influences does not arise till the 

 differentiation has been accomplished, because, when the germ- 

 cell was still one cell, the influences, which bring about the differ- 

 entiation, had not yet acted, and so (apart from engrammatic 

 factors) the results of those simultaneous influences, too, could 

 not as yet have been linked. 



So in both processes there are simultaneous influences, from which 

 originates a formative process, in both a linking of those influences; 

 in the cerebral linking, however, an integrated association of them 

 and in the development of the germ-cell a differentiated association. 

 In both cases, however, there arises a construction, which is a 

 product of correlated influences of the surroundings. 



Let us consider in this light the influence of the medium on 

 the differentiation of the cells. In order to explain how the divi- 

 sion and multiplication of the cells is at the same time attended 

 with a qualitative differentiation of the daughter-cells, it is sup- 

 posed on good experimental grounds that the two sides of the 

 mother cell, owing to their different situation — owing to the fact 

 that they are exposed to different influences — do not undergo the 

 same differentiation. 6 That from the same blastomeres entirely 



6 Wilson (also Driesch and Hertwig): "The relative! position of the blastomere 

 in the whole determines in general what develops from it; if its position be 

 changed, it gives rise to something different; its prospective value is a function 

 of its position." (The cell in development and inheritance.) 



