Nor should we be too sure that an activity whose precise function in

relation to development we cannot discover has no use at all
Nor should we be too sure that an activity whose precise function in
relation to development we cannot discover has no use at all. Each
instinct must be considered not alone in the light of what it means to
its possessor today, but of what it means to all his future development.
The tail of a polliwog seems a very useless appendage so far as the
adult frog is concerned, yet if the polliwog"s tail is cut off a perfect
frog never develops.