(IS Introduction: Variation. 



male offspring will not be allowed to perpetuate itself it would appear that 

 such females will have to breed with the finer males and their harmful effect 

 on that sex will be done away with in course of generations , because the 

 male qualities are transmitted in part to the female offspring as well as to 

 the male. 



Mr. Beddard's opinion that sexual dimorphism is mainly dependent upon 

 the reproductive organs is based upon such rare cases as that of a hermaphro- 

 dite Chaffinch (p. 262) in which one side of the bird was found to be like the 

 male in coloration, the other side like the female, with the generative systems 

 coiTes])ondingly divided'). As bearing upon the same matter may be cited the 

 circumstance that old females which have lost their fertilily sometimes assume 

 the male dress.-) Such facts appear to be very instructive, perhaps proving that 

 the sexual glands themselves through nervous influences determine the coloration 

 of the integument, intricate questions, which we are not prepared to discuss 

 here. But when Mr. Beddard suggests that the differences in disiiosition and 

 habit of very many males and females are dependent upon the sexual germ glands 

 themselves he appears to be contradicted by reasons given antea, p. 65. 



Exceptional cases. An examination of exceptions often throws more light 

 upon a matter than is afforded by the contemplation of the rule. The female of 

 the Coucal, Centrococcyx hengalensis, is much larger and stronger than the male, 

 though of similar coloration; it utters remarkable cries and is not known to take 

 any share in incubating the eggs ; the male is small, silent, and it broods on 

 the eggs. Moreover the male possesses only one testicle, the left one being 

 entirely Avanting. The conditions have been fully described by their discoverer, 

 Bernstein, in the Natuurk. Tijdschr. van Ned. Ind. 1860, pp. 27 — 49, pi. I; and 

 mentioned J. f. O. 1859, 185; 1860, 269. ^See also, suhtus, pp. 219, 220). Ap- 

 parently both Darwin, Wallace, and Beddard might claim this case as sup- 

 porting their different theories. Darwin, though he seems to have overlooked 

 the fact, anticipated the possibility of such a condition: "If we might assume 

 that the males . . . have lost some of that ardovir which is usual to their sex, 

 so that they no longer search eagerly for the females . . . then it is not im- 

 probable that the females would have been led to court the males, instead of 

 being courted by them" (Descent, p. 207). For Wallace's view it might be 

 claimed that the structural deficiency of the male points to a lower status of 

 vitality, sufficient to account for its smaller size and quiet habits. In accordance 



'j The Chaffinch quoted by Prof. Beddard was described t)y Prof Weber (ZooL Anzeiger 1890, 508). 

 Compare Prof. Cabanis' descriptions of such differently coloured halves in Pyrrhida rulgaris and Colaptes 

 7iiexieantis (J. f. 0. Ib74, 344); of v. Rosenberg's of a Chaffinch with two anterior halves of the body, the one 

 in coloration a male, the other a female iM. O. Ver. Wien 1S84 XIII. 87 & plate; and of Kleinschmidt's 

 of a bilateral -asjinmetrically coloured specimen of the Common Kingfisher Abh. u. Bcr. Zool. Mus. Dresden 

 18'.l8/9 Nr. 2 p. 73, plate III . Also the remarks of Prof Brandt on Arrhcnoidia lateralis (Z. wiss. Zool. 1889 

 XL VIII, 107) should be consulted. Lorenz asserted that he had seen a similar case in Tetrao tdrix (see: 

 Tichomirow: "On Hennaphroditism in Birds" — ^mtten in Russian — 1887 p. 21 note,, but we doubt this. 



2) "Hahnenfedi-igkeit". Comp. Meyer: Auer-, Rackel- und Birkwild 1887 p. :):). and Abh. Ber. Mus. 

 Dresden 1894/5 Nr. 3, as well as Brandt's paper quoted in note 1. 



