THE EVOLUTION OF LIVING BEINGS. 145 



is a metamorphosed hindleg of a landanimal, which 

 conclusion is about as well founded as that the door of 

 my house is a metamorphosis of the door of my neigh- 

 bour's. 



This may have happened, but need not have hap- 

 pened ; my door may have been made from that of my 

 neighbour's, by taking off something here and adding 

 perhaps something there, so as to fit my house, but it 

 may just as well, and much more probably has been, 

 constructed anew. 



So why should we accept the flapper of a seal to 

 have been formed by the changing of the hindleg of 

 a land-animal ? We know, that from a cross not one 

 type, but several types arise, so that there is no reason 

 whatever to consider all these different types to be 

 derived from the one with the simplest constitution; 

 we know on the contrary that it are just the compara- 

 tively simplest types, the recessive ones, which are en- 

 tirely unable to give rise directly to other ones. 



A type giving rise to a large number of forms must 

 on the contrary be a complicated one, allowing segrega- 

 tion. 



I hear it objected, that I am proceeding to do the 

 same I reproach to those I criticise, viz that I am on 

 the way to explain away the differences which do 

 exist between different classes. 



This is not my purpose; I only claim that the 

 ,,groundplan" is but a very general one, that we are 

 not justified to consider the simplified ,,groundplan", 

 obtained by cutting off all differences in structure 

 existing between the different organisms, as primitive, 



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