ADVERSITY. 
13 
time to believe that they were after sand crabs. They 
did not make a large bag, for they were new to the work 
and did not set about it in the right way. But if they 
had kept at it long enough, there is no doubt they would 
have improved by practice. Then, if they had trained 
their young to the same pursuit, there is no doubt the 
young would have beaten the parents. In a few genera- 
tions the structure would have followed the habits, for 
those parts of the body which are not kept up by con- 
stant use soon become unfit for use, while those parts 
which are employed in any peculiar way soon become 
adapted to their new task. We may find illustrations 
of this law everywhere. Tame ducks can scarcely fly 
a yard, but their legs are stouter than those of wild 
ducks. Darwin says that the very bones in the leg of 
the tame duck are proportionately heavier, but the wing 
bones are lighter. Among ourselves has not baldness 
followed the use of hats, and are not bad teeth, which 
decay and torture us before half their term of service 
is out, the legitimate punishment of our effeminate parti- 
ality for tender meat and soft foods ? So the claws of 
the kestrel would have lost their keenness, his beak would 
have changed its shape, his legs and toes would have grown 
I 
