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 out, agreeing in 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 
