€hap. VI. MANNER OF FORMATION OF THE CHIEF RACES. 223 



toe, or in habits of life, as in roosting and building in trees. 

 But the above objection shows how completely the principle of 

 selection has been misunderstood. It is not likely that charac- 

 ters selected by the caprice of man should resemble differences 

 preserved under natural conditions, either from being of direct 

 service to each species, or from standing in correlation with 

 other modified and serviceable structures. Until man selects 

 birds differing in the relative length of the wing-feathers or 

 toes, &c, no sensible change in these parts should be expected. 

 Nor could man do anything unless these parts happened to 

 vary under domestication : I do not positively assert 'that this 

 is the case, although I have seen traces of such variability in 

 the wing-feathers, and certainly in the tail-feathers. It would 

 be a strange fact if the relative length of the hind toe should 

 never vary, seeing how variable the foot is both in size and in the 

 number of the scutellge. With respect to the domestic races 

 not roosting or building in trees, it is obvious that fanciers 

 would never attend to or select such changes in habits ; but 

 we have seen that the pigeons in Egypt, which do not for some 

 reason like settling on the low mud hovels of the natives, are 

 led, apparently by compulsion, to perch in crowds on the trees. 

 We may even affirm that, if our domestic races had become 

 greatly modified in any of the above specified respects, and it 

 could be shown that fanciers had never attended to such points, 

 or that they did not stand in correlation with other selected 

 characters, the fact, on the principles advocated in this chapter, 

 would have offered a serious difficulty. 



Let us briefly sum up the last two chapters on the pigeon We 

 may conclude with confidence that all the domestic races, notwith- 

 standing their great amount of difference, ^descended from the 

 Golumba Iwia, including under this name certain wild races. But 

 the differences between these latter forms throw no light whatever 

 on the characters which distinguish the domestic races. In each 

 breeder sub-breed the individual birds are more variable than 

 birds in a state of nature ; and occasionally they vary in a sudden 

 and strongly-marked manner. This plasticity of organisation 

 apparently results from changed conditions of life. Disuse has 

 reduced certain parts of the body. Correlation of growth so ties 

 the organisation together, that when one part varies other parts 



