1 82 THEORETICAL BIOLOGY 



GENERAL PROLOGEMENA 



With the final proof that, at the beginning of embryonic 

 ^ shaping, there is no framework in the germ, but that there 

 is a rule, the modern doctrine of the genesis of the organism 

 began. What the nature of this rule is can be deduced only 

 after the history of the genesis has been laid clear. The 

 question " How does a rule affect the protoplasm of the 

 germ ? ", we answered when we considered the super- 

 mechanical powers of protoplasm, by saying that it arranges 

 the impulse-sequence. 



As intermediary between the non-spatial rules and proto- 

 plasm, which is arranged with relation to space, we have 

 placed the impulse, and about that we must now say some- 

 thing briefly. The impulse sets going a process in the proto- 

 plasm. We may picture this by analogy with the effect of 

 ferments or catalysers. But whereas the physicists and 

 physiologists have developed purely material conceptions of 

 these releasing factors, and arranged them in the causal series, 

 we must ascribe to the impulses a semi-immaterial character, 

 which permits them, on the one hand, to initiate new causal 

 series, but, on the other, places their becoming effective 

 under the control of a rule that is in conformity with plan. 

 As an analogy, we may refer to the way sounds appear under 

 compulsion of the melody. 



To Karl Ernst von Baer, " the father of embryology," 

 belongs the merit of having compared the laws of melody 

 with those that shape the germ. 



But the discoverer of the impulses was Mendel. 



The story of this discovery will ever be worthy of re- 

 membrance. In the sexual crossing of peas Mendel discovered 

 the rule of interchange of the rudiments of characters, a rule 

 which holds good for sexual crossings in all organisms. But, 

 as happens to great geniuses whose intellectual course lies far 



