Chap. VIII. SEXUAL SELECTION. 261 



attractive males. Unless this result should follow, the 

 characters which give to certain males an advantage 

 over others, could not be perfected and augmented 

 through sexual selection. When the sexes exist in 

 exactly equal numbers, the worst-endowed males will 

 ultimately find females (except where polygamy pre- 

 vails), and leave as many offspring, equally well fitted for 

 their general habits of life, as the best-endowed males. 

 From various facts and considerations, I formerly in- 

 ferred that with most animals, in which secondary sexual 

 characters are well developed, the males considerably 

 exceeded the females in number; and this does hold 

 good in some few cases. If the males were to the 

 females as two to one, or as three to two, or even in 

 a somewhat lower ratio, the whole affair would be 

 simple ; for the better-armed or more attractive males 

 would leave the largest number of offspring. But after 

 investigating, as far as possible, the numerical propor- 

 tions of the sexes, I do not believe that any great 

 inequality in number commonly exists. In most cases 

 sexual selection appears to have been effective in the 

 following manner. 



Let us take any species, a bird for instance, and 

 divide the females inhabiting a district into two equal 

 bodies: the one consisting of the more vigorous and 

 better-nourished individuals, and the other of the less 

 vigorous and healthy. The former, there can be little 

 doubt, would be ready to breed in the spring before the 

 others ; and this is the opinion of Mr. Jenner Weir, who 

 has during many years carefully attended to the habits 

 of birds. There can also be no doubt that the most 

 vigorous, healthy, and best-nourished females would on 

 an average succeed in rearing the largest number of 

 offspring. The males, as we have seen, are generally 

 ready to breed before the females ; of the males the 



