A great amount of variability, under which term individual differences are always included, will evidently be favourable.

大量的可变性， 在这个术语下总是包括个体差异， 显然是有利的。

An extraordinary amount of modification implies an unusually large and long-continued amount of variability, which has continually been accumulated by natural selection for the benefit of the species.

大量的修改意味着异常大且长期持续的可变性，为了物种的利益， 这种可变性通过自然选择不断积累。

A large number of individuals, by giving a better chance within any given period for the appearance of profitable variations, will compensate for a lesser amount of variability in each individual, and is, I believe, a highly important element of success.

大量的个体， 通过在任何给定时期内为出现有利可图的变化提供更好的机会，将补偿每个人较小的可变性， 我相信这是成功的一个非常重要的因素。