70 CREATIVE EVOLUTION CHAP 



to each other, and so related to former complications 

 as to go further on in the same direction ? How, 

 especially, can we suppose that by a series of mere 

 &quot; accidents &quot; these sudden variations occur, the same, 

 in the same order, involving in each case a perfect 

 harmony of elements more and more numerous and 

 complex, along two independent lines of evolution ? 



The law of correlation will be invoked, of course ; 

 Darwin himself appealed to it. 1 It will be alleged 

 that a change is not localized in a single point of the 

 organism, but has its necessary recoil on other points. 

 The examples cited by Darwin remain classic : white 

 cats with blue eyes are generally deaf ; hairless dogs 

 have imperfect dentition, etc. Granted ; but let us not 

 play now on the word &quot;correlation.&quot; A collective 

 whole of solidary changes is one thing, a system of 

 complementary changes changes so coordinated as 

 to keep up and even improve the functioning of an 

 organ under more complicated conditions is another. 

 That an anomaly of the pilous system should be 

 accompanied by an anomaly of dentition is quite 

 conceivable without our having to call for a special 

 principle of explanation ; for hair and teeth are 

 similar formations, 2 and the same chemical change of 

 the germ that hinders the formation of hair would 

 probably obstruct that of teeth : it may be for the 

 same sort of reason that white cats with blue eyes 

 are deaf. In these different examples the &quot; cor 

 relative &quot; changes are only solidary changes (not to 

 mention the fact that they are really lesions, namely, 

 diminutions or suppressions, and not additions, which 



1 Darwin, Origin of Species, chap. i. 



2 On this homology of hair and teeth, see Brandt, &quot;tiber . . . eine 

 mutmassliche Homologie der Haare und Zahne &quot; (BioL Centralblatt, vol 

 xviii., 1898, especially pp. 262 ff.). 



