After a chase of a whole day, which effected nothing but the fatigue of the party, he began to despair of success.

后来在追了整整一天后，队伍疲劳极了却一无所获，他开始丧失信心了。

What applies to one animal will apply throughout all time to all animals—that is, if they vary—for otherwise natural selection can effect nothing.

适用于一种动物的东西将始终适用于所有动物——也就是说， 如果它们有所不同——否则自然选择就不会产生任何影响。