Hence, the structure of each part of each species, for whatever purpose it may serve, is the sum of many inherited changes, through which the species has passed during its successive adaptations to changed habits and conditions of life.

因此，无论出于何种目的， 每个物种的每个部分的结构都是许多遗传变化的总和，该物种在不断适应变化的生活习惯和条件的过程中经历了这些变化。