Page:Descent of Man 1875.djvu/13
Principles of Sexual Selection.
|Secondary sexual characters — Sexual selection — Manner of action — Excess of males — Polygamy — The male alone generally modified through sexual selection — Eagerness of the male — Variability of the male — Choice exerted by the female — Sexual compared with natural selection — Inheritance at corresponding periods of life, at corresponding seasons of the year, and as limited by sex — Relations between the several forms of inheritance — Causes why one sex and the young are not modified through sexual selection — Supplement on the proportional numbers of the two sexes throughout the animal kingdom — The proportion of the sexes in relation to natural selection||207|
Secondary Sexual Characters in the Lower Classes of the Animal Kindgom.
|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||260|
Secondary Sexual Characters of Insects.
|Diversified structures possessed by the males for seizing the females — Differences between the sexes, of which the meaning is not understood — Difference in size between the sexes — Thysanura — Diptera — Hemiptera — Homoptera, musical powers possessed by the males alone — Orthoptera, musical instruments of the males, much diversified in structure; pugnacity; colours — Neuroptera sexual differences in colour — Hymenoptera, pugnacity and colours — Coleoptera, colours; furnished with great horns, apparently as an ornament; battles; stridulating organs generally common to both sexes||274|