64 Permanence and Evolution. 



with a view to singularity, e.g., if the prototype 

 of the carrier was a much larger bird, then its 

 long neck and huge bill would have been much 

 more appropriate. 



Then as to the individual birds in various 

 breeds marked like the rock dove, either 

 these are crossed or not ; if they are, cadit 

 qucestio, if not, then on the hypothesis of 

 limited variability, they depend on creatures 

 with similar constitutions being attacked by 

 circumstances in the same way ; leaving the 

 cause of this similarity undecided, on the 

 hypothesis of no variation, all the breeds may 

 have contained sub-strains ab origine coloured 

 like the rock dove. Darwin maintains and gives 

 instances to show that rock dove markings have 

 a tendency to spring up when different breeds 

 are crossed. But in none of these cases does he 

 appear to know much about the pedigree of the 

 particular birds, but pins his faith on generalities, 

 on the unlikelihood of reversion acting for more 



