THE PROBLEM OF THE ORIGIN OF SPECIES. 



19 



With reduction traveling from before backward, in the manner described, we 

 get the bars in their typical number, form, and position, as one of the necessary 

 stages of the process, and without appealing to de novo origin, incipient rudiments, 

 etc. But if bars originated in such simple fashion the direction of evolution 

 being precisely the same as that of embryological development if the theory of 

 rudiments must be abandoned in this case, do we not meet the same theory again 

 in any attempt to account for the chequers? What kind of rudiments could be 

 imagined? We might assume that minute flecks of pigment first appeared, one in 

 each feather; and then, further, imagine that these purely chance originations 



TEXT-FIGURE 3. Oriental or Japanese turtle-dove, Turtur orientalis. x 0.5. Toda del., 

 1903. The color-pattern in black and white. The light-brownish or bronzed edges 

 of the feathers given in white, the dark centers in black. This pattern is preserved 

 in the feathers of the neck-mark. 



happened to have some slight utility, and that natural selection did the rest. But 

 it is just as difficult to account for a small as a large origin de novo, and the smaller 

 it is the more unfortunate it is for the theory of natural selection. 



If we seek refuge in the doctrine of mutation, are we better off? Mutation hides 

 itself in the undiscoverable premutation, and so we have all the difficulty of an 

 incipient stage, and no means of advancing by ordinary variation. Fortunately 

 we are not driven to either alternative, for the chequers arise neither as mutations 

 nor as rudiments, but by direct and gradual modifications of an earlier ancestral 

 mark, which came with the birth of the pigeon phylum as a heritage from still 

 more distant avian ancestors. 



