CONFORMITY WITH PLAN 317 



it is true, always possesses many more properties than the 

 animal requires for the construction of its surrounding-world, 

 but by no means enough to satisfy all animals. We have, 

 accordingly, the remarkable fact that there are actually a 

 limited number of certain properties present in the external 

 world, for which the animal, if it is to prosper, must develop 

 in its bodily structure corresponding counter-properties, 

 which shall fit in with these like pegs and sockets. 



The external world offers to the organism a certain number 

 of properties separated in space and in time, from which to 

 select, and therewith the possibility of making a poorer or a 

 richer surrounding-world. But the external world itself takes 

 no part in the selection, which has to be made by the organism 

 without external assistance. 



We have to come to terms with this fact : on the one 

 side are the properties of the external world, which exercise 

 no direction-giving influence ; and on the other is the living 

 germ, which possesses no organs that could give it knowledge 

 of these properties. And yet we see how the embryo un- 

 erringly produces definite counter-properties, which fit into a 

 definite group of properties in the external world. 



Since the discovery of the genes, we know that in the 

 germinal rudiments all the pegs and sockets of the counter- 

 properties are present, and these they only have to shape 

 according to a certain rule, in order for the congruity with 

 the external world to be complete. . 



As we know, the rule of shaping is not mechanical, but 

 is borne by other factors than those with which we are 

 acquainted through physics and chemistry. I have called 

 these factors impulses, and have shown that they are enclosed 

 in an impulse-system, having an internal equilibrium both of 

 a spatial and of a temporal kind. 



It only remains to show that the impulse-systems corre- 

 spond with the groups of properties in the external world, just 



^y^ 



