Chap. XVI. THE YOUNG LIKE BOTH ADULTS. 215 



played as important a part, as I believe it lias, in 

 giving ornamental colours, plumes, &c., to the males, 

 and, by means of equal transmission, to the i'emales of 

 many species. The objection would be a valid one, if 

 the younger and less ornamented males were as suc- 

 cessful in winning females and propagating their kind, 

 as the older and more beautiful males. But we have 

 no reason to suppose that this is the case. Audubon 

 speaks of the breeding of the immature males of Ibis 

 tantalus as a rare event, as does Mr. Swinhoe, in re- 

 gard to the immature males of Oriolus.^^ If the young 

 of any s]3ecies in their immature plumage were more 

 successful in winning partners than the adults, the 

 adult plumage would probably soon be lost, as the 

 males which retained tlieir immature dress for the 

 longest period would prevail, and thus the character of 

 the species would ultimately be modified.^^ If, on the 

 other hand, the young never succeeded in obtaining a 

 female, the habit of early reproduction would perhaps 

 be sooner or later quite eliminated, from being super- 

 fluous and entailing waste of power. 



The plumage of certain birds goes on increasing in 



38 See the last foot-note. 



^^ Other animals, belonging to qnite dibtinct 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 Miiller has shewn (' Facts 

 and Arguments for Darwin,' Eng. trans. 1869, p. 79) tliat 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. 



