TOOLS AND TASKS AMONG THE BIRDS. 145 
would feel the surest; and the one having the nos- 
trils nearest the tip would smell the best. Hence in 
the struggle for existence in the ancient swamps the 
birds that had all these fortuitous combinations 
would most likely survive and be the ancestors of 
other fortunately endowed birds. but this view does 
not at all account for the reason why one of these 
good qualities does not develop beyond the other; 
why the long bill might not be better than the sensi- 
tive bill, and why feeling highly developed might not 
suppress smell. There is what is called a “nice cor- 
relation” of all these factors here that mere selection 
does not account for. Neither can the effects of use 
only account for the change, since there is surely 
nothing in the act of prodding that would tend to 
make a beak slimmer and softer—in fact, just the 
contrary. There is then in the making of this tool 
other forces that we know not of which nicely balance 
all these shaping factors to a certain end, as if a Great 
Power of Purpose throbbed beneath them all. 
Nevertheless it can in most instances be shown 
that all forms of organisms have been brought about 
gradually, and we can frequently see many of the 
developing forces; and in our present discussion we 
may perceive how the tool has usually been adapted 
to the task. Some species of Apteryx have shorter 
beaks than others. Thus the change in the style of 
feeding or the nature of the food at hand may have 
set up the fringes on the bills and tongues of ducks ; 
the pelican’s rear toe was webbed forward with the 
others (from an evident condition when it was once 
