21 8 THEORETICAL BIOLOGY 



it exerts its influence. The impulse-system merely conforms 

 to the position that it takes up in the system of impulses as 

 a whole, and if in so doing it comes upon suitable material, 

 containing the right sort of genes, all goes well. 



What goes on in the adjacent system is a matter of com- 

 plete indifference to the individual part-system. Thus, after 

 complete removal of a nervous germinal area, perfectly 

 developed limbs have successfully been produced, which 

 were nevertheless entirely destitute of nerves. 



The individual impulse-system is dependent on the material 

 only in so far as that must yield the suitable genes if the 

 ^^ system is to become manifest. It is dependent on the 

 adjacent systems only in so far as its fixed position is deter- 

 mined by its being set between them. For the rest, develop- 

 ment within each system proceeds quite independently, 

 according to the general rhythm which is prescribed to the 

 systems collectively ; it is all one whether the normal quantity 

 of material is present, and there is no regard paid as to whether 

 adjacent systems shape structures in a normal way, or pro- 

 duce only a reduced organ, or no organ at all. 



All of which proves to us the existence of an independent 

 natural factor, representing a self-contained rule built up 

 of part-rules, which, on their side, arrange the impulses both 

 in space and in time. 

 >si Once the impulses are set free, it does not matter whether 



they achieve a material effect or not ; the rule of genesis 

 proceeds calmly on its way, and sends forth its impulses 

 according to its own law and rhythm. 



The rule, although it breaks up into separate part- 

 rules, is in itself quite independent of space and time. 

 The impulses that obey the rule, are fixed in space and time, 

 but in themselves are still completely non-material. But, 

 since they are attached to the genes, they dominate the 

 material, for that is set in motion by the fermentative action 



^;^ 



