STERILITY OF HYBRIDS 235 



mechanisms is no greater than it has always been. On the con- 

 trary the fact that variations can now so generally be recognized 

 as definite is some alleviation of the difficulty. We can moreover 

 disabuse ourselves of the notion that for all characters which are 

 definite or fixed, some utilitarian rationale may be presumed. 

 Upon that point the study of variation has provided a perfectly 

 clear answer. 



In frankly recognizing that the fixity of characters in general 

 need not connote usefulness to their possessors we deliver our- 

 selves of a distracting pre-occupation and prepare our minds for 

 an investigation of the properties of living organisms in the 

 same spirit as that in which the chemist and the physicist 

 examine the properties of unorganized materials. The creature 

 persists not merely by virtue of its characteristics but in spite 

 of them, and the fact of its persistence proves no more than 

 that on the whole the balance of its properties leaves something 

 in its favour. 



It may be noted by the way that the fact that the structures 

 of living things are on the whole adaptative was not always 

 obvious. Though to naturalists of this generation it is a truism, 

 we have only to turn to Buffon to find that in his philosophy of 

 nature it played no essential part. The passage in which Buffon 

 describes what he regards as the forlorn and degraded condition 

 of the Woodpecker is well known. We have come to think of 

 the Woodpecker as a capital example of adaptation to the mode 

 of life; but Buffon after enumerating the hard features of the 

 bird's existence, forced to earn its living by piercing the bark of 

 trees in an attitude of perpetual constraint, remarks 1 " Tel est 

 l'instinct etroit et grossier d'un oiseau borne a une vie triste et 

 chetive. II a recu de la Nature des organes et des instrumcns 

 appropries a cette destinee ou plutot il tient cette destinSe memo 

 des organes avec lesquels il est ne " (my italics). His reflexions 

 on the Stilt (Hitnantopus) read even more strangely to us, 

 accustomed as we are to see in the prodigious length and thinness 

 of the shanks and in the other features of its organisation pal- 

 pable adaptations to a wading life. For Buffon, however, this 



1 Buffon, Hist. Nat., Oiseaux, 1780, VII, p. 3- 



