236 PROBLEMS OF GENETICS 



curious bird seemed a poor, neglected production, extravagant 

 in its disproportions, one of the misfits of creation, left as a 

 shadow in the picture composed of nature's more successful 

 efforts. 2 This theme he develops at some length, being evidently 

 well pleased with the idea. 



Our way of regarding these things is doubtless sounder and 

 more fruitful than Buffon's, but it is well to remember that what 

 seems so obvious to us looked quite differently to other excellent 

 observers; and stupid as it may have been to have overlooked 

 plain examples of adaptation, it is a far worse mistake to see 

 adaptation everywhere. I do not seek to minimise the real 

 and permanent difficulty which the existence of adaptations 

 creates, but by the suggestion that all normal specific differences 

 are adaptational that difficulty was quite gratuitously increased. 



In these respects it may be claimed that progress has been 

 made, even if that progress seem outwardly of small account. 



But all constructive theories of evolution have been built on 

 the understanding that what we know of the relation of varieties 

 to species justifies the assumption that the one phenomenon is a 

 phase of the other, and that each species arises or has arisen 

 from another species either by one or several genetic steps. In 

 the varieties we have accustomed ourselves to think that we see 

 those steps. We still know little enough of the mode of occur- 

 rence of variation, but we do begin to know something, and if we 

 ask ourselves whether our knowledge, such as it is, conforms at 

 all readily with our former expectations, we cannot with any 

 confidence assert that it does. Among the plants and animals 

 genetically investigated are many illustrations of very striking 

 and distinct varieties. Many of these might readily enough be 

 accepted as species by even the most exacting systematists, and 

 not a few have been so treated in classification; but when we 

 have examined their relationship to each other we feel not merely 

 that they are not species in any strict sense but that the dis- 

 tinctions they present cannot be regarded as stages in the direc- 

 tion of specific difference. Complete fertility of the results of 

 inter-crossing is and I think must rightly be regarded as incon- 



2 ibid., viii, p. 115. 



