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Updated: June 24, 2025
Dutch, retention of their colour by the, in South Africa. Duty, sense of. Duvaucel, female Hylobates washing her young. Dyaks, pride of, in mere homicide. Dynastes, large size of males of. Dynastini, stridulation of. Dytiscus, dimorphism of females of; grooved elytra of the female. Eagle, young Cercopithecus rescued from, by the troop. Eagle, white-headed, breeding in immature plumage.
Distinction between the sterility of first crosses and of hybrids Sterility various in degree, not universal, affected by close interbreeding, removed by domestication Laws governing the sterility of hybrids Sterility not a special endowment, but incidental on other differences, not accumulated by natural selection Causes of the sterility of first crosses and of hybrids Parallelism between the effects of changed conditions of life and of crossing Dimorphism and trimorphism Fertility of varieties when crossed and of their mongrel offspring not universal Hybrids and mongrels compared independently of their fertility Summary.
The first hatching, that of the normal egg, makes the Meloid go through the larval dimorphism of the Anthrax and the Leucospis. The primary larva finds its way to the victuals; the secondary larva consumes them. The second hatching, that of the pseudochrysalis, reverts to the usual course, so that the insect passes through the three customary forms: larva, nymph, adult.
We have here a curious and inexplicable case of dimorphism, for some of the females of four European species of Dytiscus, and of certain species of Hydroporus, have their elytra smooth; and no intermediate gradations between the sulcated or punctured, and the quite smooth elytra have been observed. See Dr. H. Schaum, as quoted in the 'Zoologist, vols. v.-vi. 1847-48, p. 1896.
These characters absent in the lowest classes Brilliant colours Mollusca Annelids Crustacea, secondary sexual characters strongly developed; dimorphism; colour; characters not acquired before maturity Spiders, sexual colours of; stridulation by the males Myriapoda.
As I pointed out in my Sexual Dimorphism , the common characteristic of somatic sexual characters is their adaptive relation to some function in the sexual habits of the species in which they occur. All other differences, therefore, including genital ducts and copulatory or intromittent organs, are somatic.
Bateson offers no explanation of this, but it obviously suggests that some trace of the original dimorphism of the sheep in this character was retained in both horned and hornless breeds.
Nemertians, colours of. Neolithic period. Neomorpha, sexual difference of the beak in. Nephila, size of male. Nests, made by fishes; decoration of, by Humming-birds. Neumeister, on a change of colour in pigeons after several moultings. Neuration, difference of, in the two sexes of some butterflies and hymenoptera. Neuroptera. Neurothemis, dimorphism in.
Summarizing the results of this discussion, we may state that useful dimorphism, or double adaptation, is a substitution of characters quite analogous to the useless dimorphism of cultivated ever-sporting varieties and the stray occurrence of hereditary monstrosities. The same laws and conditions prevail in both cases.
He also discusses the case of Abraxas grossulariata and its variety lacticolor, and other cases of sex-linked heredity, apparently with the idea that all such cases are similar to those of sexual dimorphism.
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