Note 267 — Chapter XVI

Other animals, belonging to quite distinct classes, are either habitually or occasionally capable of breeding before they have fully acquired their adult characters. This is the case with the young males of the salmon. Several amphibians have been known to breed whilst retaining their larval structure. Fritz Müller has shewn (‘Facts and Arguments for Darwin,’ Eng. trans. 1869, p. 79) that the males of several amphipod crustaceans become sexually mature whilst young; and I infer that this is a case of premature breeding, because they have not as yet acquired their fully-developed claspers. All such facts are highly interesting, as bearing on one means by which species may undergo great modifications of character, in accordance with Mr. Cope’s views, expressed under the terms of the “retardation and acceleration of generic characters;” but I cannot follow the views of this eminent naturalist to their full extent. See Mr. Cope, “On the Origin of Genera,” from the ‘Proc. of Acad. Nat. Sc. of Philadelphia,’ Oct. 1868.