A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation, on the effects of use and disuse, on the direct action of external conditions, and so forth.
宏伟而几乎无人涉足的研究领域将被打开,涉及变异的原因和规律、相关性、使用和废弃的影响、外部条件的直接作用等等。