Heredity and sex . Fig. 14. — White-booted humming bird, two malesand one female. (After Gould.) The phosphorescent organ of our common firefly,Photinus pyralis, is a beautiful illustration of a second-ary sexual character. On the under surface of the malethere are two bands and of the female there is a singleband that can be illuminated (Fig. 18). At night themales leave their concealment and fly about. A littlelater the females ascend to the tops of blades of grass THE EVOLUTION OF SEX 29. Fig. 15. — Male and female bobolink. (From Bird Lore.)

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Keywords: ., boo, bookcentury1900, bookdecade1910, booksubjectsex, bookyear1913