CHAPTER 11. 



The Sexes, and Criticism of Sexual Selection. 



§ I. To gain a firmer and broader foundation on which to 

 base a theory of the differences between the sexes, it is ne- 

 cessary to take another review of the facts of the case. Instead 

 of considering the differences as they are expressed in the 

 successive classes of animals, it will be more convenient to 

 arrange them for themselves, according as they affect habit, 

 size, length of life, and the like. The review must again be 

 merely representative, without any attempt at completeness. 



Male and Female Coccus Insects, a, part of a cactus 

 plant with the excrescences due to coccus insects ; 

 b, male ; c, female. 



§ 2. Ge?ieral Habit. — Let us begin with an extreme yet 

 well-known case. The female cochineal insect, laden with 

 reserve products in the form of the well-known pigment, spends 



