The distinction of species he explains by the destruction of intermediate graduated forms.

他通过中间分级形式的破坏来解释物种的区别。

After all, what did the intermediate forms look like?

究竟，中间那 过度的形式是什么样子的呢？

In the first place, it should always be borne in mind what sort of intermediate forms must, on the theory, have formerly existed.

首先，应该始终牢记在理论上必须存在什么样的中间形式。

The apparent absence of intermediate forms of language -- say, a talking animal -- left the question of how language evolved resistant to empirical inquiry.

语言中间形式的明显缺失——比如会说话的动物——留下了语言如何进化而无法抵抗实证探究的问题。

Natural selection, as has just been remarked, leads to divergence of character and to much extinction of the less improved and intermediate forms of life.

正如刚才所说， 自然选择导致性格的分化， 并导致改良程度较低的和中间的生命形式大量灭绝。

Hence all the intermediate forms between the earlier and later states, that is between the less and more improved states of a the same species, as well as the original parent-species itself, will generally tend to become extinct.

因此，早期和晚期状态之间的所有中间形式，即同一物种的改良程度较低和改良程度较高的状态之间的所有中间形式，以及原始亲本物种本身， 通常都会趋于灭绝。