38 EVOLUTION 



measure of success in each individual. This increase, 

 being accumulated by inheritance in every succeeding 

 generation, ultimately led to the great stature exhibited 

 by the giraffes of the present day. 



The stilt-like legs of many wading birds were ascribed 

 by Lamarck to the result of the continued attempts of 

 ancestors which had shorter extremities to obtain their 

 food in shallow water without wetting their feathers. 

 The long-continued endeavours of these birds to stretch 

 and elongate their legs had the same effect as the 

 similar efforts made by the ancestors of the giraffes. 

 It has been suggested, however, by a critic of Lamarck's 

 position that such birds would be likely to eschew fish 

 dinners long before any notable increase in the length 

 of their legs was arrived at. 



If some of the above cases appear a little ludicrous, 

 there are other instances in which the Lamarckian 

 hypothesis seems to afford a perfectly adequate and 

 natural explanation. Such a case is afforded by the 

 family of the flat fishes* including such well-known 

 species as the sole and plaice. In the adult condition 

 these fishes lie flat on one side ; and during their 

 development from the young condition, that eye which, 

 if it remained in its original position, would look 

 directly downwards travels round the head until it 

 comes to lie quite upon the upper surface. As Darwin 

 pointed outj agreeing hi this with Mivart* a sudden 

 spontaneous transformation in the position of the eye 

 is hardly conceivable, and it is equally impossible to 

 explain the origin of this remarkable feature by the 

 action of natural selection, because a slight change 



