II. Remarks on variation in animals and plants. To accompany the first report of the committee for conducting statistical inquiries into the measurable characteristics of plants and animals

1. The importance of variation as a factor in organic evolution is not seriously disputed; but, if one may judge from the expressions contained in recent essays, naturalists are not agreed as to the manner in which variation among individuals is associated specific modification. The view originally put forward by Darwin and Wallace is that specific modification is at least generally a gradual process, resulting from “the accumulation of innumerable slight variations, each good for the original possessor” (‘Origin of Species,’ chap. xv). This view rests on the assumption that each of those small differences which are to be observed among a group of individuals belonging to the same species has generally some effect upon the chance of life.