It is also necessary to bear in mind that, owing to the law of correlation, when one part varies and the variations are accumulated through natural selection, other modifications, often of the most unexpected nature, will ensue.

还有必要记住， 由于相关定律， 当一部分发生变化并且变化是通过自然选择积累起来的时，就会发生其他修改， 通常是最意想不到的。