36 THE EVOLUTION THEORY 



division, on which all organic growth depends, unless we are to 

 assume, as Nageli did, a continual generatio cequivoca of the specific 

 kinds of biophors (his 'micellae'). But we shall see later, when we 

 come to speak of spontaneous generation, that we cannot acquiesce 

 in such an assumption. If, then, we cannot conceive of a power 

 of division arising from within and depending solely on growth 

 by means of assimilation, without such attractive and repellent 

 forces or 'vital affinities' the internal parts would necessarily fall 

 into disorder at every division. It seems to me therefore that such 

 ' affinities ' must be operative at all stages in the life of the vital 

 units, not only in biophors, but also in the cell, and in the ' person ' 

 as well as in determinant and id. It is true that ' persons ' no longer 

 generally possess the power of multiplying by division, but in plants 

 and lower animals many do possess it ; and the power of giving rise 

 anew to certain parts is obviously a part of that power of doubling 

 the whole by division. The ultimate roots of regeneration, then, 

 must lie in these 'affinities' between the parts, which preside over 

 their arrangement and are able to maintain it and to give rise to it 

 anew. In this respect the organism appears to us like a crystal 

 whose broken points always complete themselves again from the 

 mother-lye after the same system of crystallization, obviously in 

 this case too as a result of certain internal directive forces, polarities, 

 which here again we are unable precisely to define. But the differ- 

 ence between the organism and the crystal does not — as people have 

 been hitherto inclined to believe — lie only in the fact that the crystal 

 requires the mother-lye to complete itself, while the vital unit itself 

 procures the material for its further growth ; it lies also in the fact 

 that such regeneration is not possible in every organism and at every 

 place, but that special ' primary constituents ' are necessary, without 

 which the relevant part cannot arise. The indispensableness of these 

 primary constituents, the determinants, seems to me to depend on the 

 fact that the new structure cannot be built up simply by procuring 

 organic material, but that specially heiun stones, different in every case, 

 are necessary, which can only be supplied in virtue of an historical 

 transmission, or, to abandon the metaphor, because the vital units 

 of which the organ is to be reconstructed possess a specific character 

 and have a long history behind them ; thus they can only arise from 

 such vital units as have been handed on through generations, that 

 is, from the determinants. But these primary constituents are given 

 to the difi"erent forms of life in very varying degrees and in very 

 unequal distribution, and as far as we can see according to their 

 sixitability to an end. 



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