1 90 O^'thoplasy 



cesses represents ; they would thus miss being in the same 

 degree Hke their parents. In short, recapitulatio7i is a si?ie 

 qua non of Jiercdity. 



This ajDpears reasonable ; and it becomes more so when 

 we take the point of view of concurrence. For on that 

 view, future evolution in succeeding generations is to be in 

 the lines marked out by accommodation in the preceding 

 generations. If this is also to exhibit itself in the process 

 of development, then it is the more important that the 

 offspring in each case should have new elements of en- 

 dowment (variation), not inconsistent with the processes 

 of development through which the parents also acquired 

 theirs. This would extend backward from generation to 

 generation. In other words, variations, to be effective in 

 the same functional lines with accommodation, should be 

 consistent with the processes of development already estab- 

 Hshed, up to the point from which accommodations to the 

 environment, of Hke nature to themselves, have been found 

 possible. 



This additional point may be put in some such way as 

 this : not only is recapitulation a sine qua non of heredity, 

 but recapitulation plus variation is a sine qua non of Jiercd- 

 ity plus concurrcjice. Variation and modification which 

 concur in direction are most likely from processes which 

 are common to the two genetic series to which they respec- 

 tively belong. 



Referring to the diagrams given in the last paragraph 

 (pp. 187 f.) for natural selection (Neo-Darwinism) and 

 orthoplasy, the two points just made may be illustrated 

 from them. Referring to the natural selection diagram, it 

 appears that the individual development r;;/'", in order to 

 issue in an adult showing heredity from r;//', must go 



