Part II.— SEXUAL SELECTION. 
CHAPTER VIII. 
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 ot the male 
Variability of the male — Choice exerted by the female — Sexual 
compared w ith 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 — On the limita- 
tion of the numbers of the two sexes through natural selection. 
With animals which have their sexes separated, the 
^ales necessarily diffeT from the females in their organs 
°f reproduction ; and these afford the primary sexual 
characters. But the sexes often differ in what Hunter 
has called secondary sexual characters, which are not 
Erectly connected with the act of reproduction; for 
^stance, in the male possessing certain organs of sense 
0r locomotion, of which the female is quite destitute, or 
hi having them more highly-developed, in older that 
he may readily find or reach her ; or again, in the male 
having special organs of prehension so as to hold her 
securely. These latter organs of infinitely diversified 
hinds graduate into, and in some cases can hardly be 
distinguished from, those which are commonly ranked 
as primary, such as the complex appendages at the 
a Pex of the abdomen in male insects. Unless indeed 
