Note 72 — Chapter V · EVOLUTION.

“If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous successive slight modifications, my theory would absolutely break down.”—Darwin, Origin of Species, 5th ed. p. 227. In several passages insistence is made on this. “Natura non facit saltum” may be perfectly true; but without impugning the Law of Continuity we may urge that the Law of Discontinuity is equally true. The one is an abstract ideal conception; the other is a concrete ideal conception. According to the one, every change from rest to motion, or from one state to another, must pass through infinites; according to the other every change is abrupt. In my First Series, Vol. I. p. 327, I have shown how, on mechanical principles, every change in an organism must be abrupt. A glance at the metamorphoses of the embryo, or the stages of insect-development, will show very sudden and abrupt changes. Let me also cite Mr. Darwin against himself: “When we remember such cases as the formation of the more complex galls, and certain monstrosities, which cannot be accounted for by reversion, cohesion, etc., and sudden, strongly marked deviations of structure, such as the appearance of a moss-rose on a common rose, we must admit that the organization of the individual is capable through its own laws of growth, under certain conditions, of undergoing great modifications, independent of the gradual accumulation of slight inherited modifications.”—Origin, p. 151. See also note to § 130, further on, p. 142.