Heredity and sex . Fig. 54. — Male to left with horns and female to right without horns of afly, Elaphomyia. (After Wood.) females. The males of certain beetles have horns —the female lacks them (Fig. 52). In a genus of flies the eyes are stalked, and the SECONDARY SEXUAL CHARACTERS 107 eyes of the male have stalks longer than those ofthe female (Fig. 53). In another genus of flies thereare horns on the head like the antlers of the stag(Fig. 54). In the spiders the adult males are sometimes verysmall in comparison with the females (Fig. 55). Thesize difference may be regarded as a secondary se
Heredity and sex . Fig. 54. — Male to left with horns and female to right without horns of afly, Elaphomyia. (After Wood.) females. The males of certain beetles have horns —the female lacks them (Fig. 52). In a genus of flies the eyes are stalked, and the SECONDARY SEXUAL CHARACTERS 107 eyes of the male have stalks longer than those ofthe female (Fig. 53). In another genus of flies thereare horns on the head like the antlers of the stag(Fig. 54). In the spiders the adult males are sometimes verysmall in comparison with the females (Fig. 55). Thesize difference may be regarded as a secondary sexual. Fig. 55. — Male (to left) and female (to right) of a spider, Argiope aurelia.(From Cambridge Natural History.) character. Darwin points out, since the male is some-times devoured by the female (if his attentions arenot desired), that his small size may be an adaptationin order that he may more readily escape. But thepoint may be raised as to whether he is small in orderto escape; or whether he is eaten because he is one of our native spiders, Hahrocestum splendida,the adult males and females are conspicuously different 108 HEREDITY AND SEX in color — the male more highly colored than thefemale. In another native species, Maevia vittata,there are two kinds of males, both colored differentlyfrom the female. Passing over the groups of fishes and reptiles inwhich some striking cases of differences between thesexes occur, we come to the birds, where we find thebest examples of secondary sexual characters.
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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectsex, bookyear1913
