Why should there often be so great a difference in the result of a reciprocal cross between the same two species?

为什么相同两个之间互交结果往往会有如此？

Hybrid plants produced from a reciprocal cross generally resemble each other closely, and so it is with mongrel plants from a reciprocal cross.

由互惠杂交产生杂交植通常彼此非常相似， 来自互惠杂交植也是如此。

By a reciprocal cross between two species, I mean the case, for instance, of a female-ass being first crossed by a stallion, and then a mare by a male-ass: these two species may then be said to have been reciprocally crossed.

所谓两个之间相互杂交， 我指是母驴首先与马杂交，然后母马与公驴杂交情况：这两个可以说是相互杂交.