678 TRE DESCENT OF MAN 



transmitting to their female ofEspring their own brightness, 

 would have to be eliminated by a change in the form of in- 

 heritance; and this, as shown by our previous illustration, 

 would be extremely difficult. The more probable result of 

 the long-contiaued destruction of the more brightly colored 

 females, supposing the equal form of transmission to prevail, 

 would be the lessening or annihilation of the bright colors 

 of the males, owing to their continual crossing with the 

 duller females. It would be tedious to follow out all 

 the other possible results; but I may remind the reader 

 that if sexually limited variations in brightness occurred 

 in the females, even if they were not in the least injurious 

 to them, and consequently were not eliminated, yet they 

 would not be favored or selected, for the male usually ac- 

 cepts any female, and does not select the more attractive 

 individuals; consequently these variations would be liable 

 to be lost, and would have little influence on the character 

 of the race; and this will aid in accounting for the females 

 being commonly duller colored than the males. 



In the eighth chapter instances were given, to which 

 many might here be added, of variations occurring at vari- 

 ous ages, and inherited at the corresponding age. It was 

 also shown that variations which occur late in life are com-, 

 monly transmitted to the same sex in which they first ap- 

 pear; while variations occurring early in life are apt to be 

 transmitted to both sexes; not that all the cases of sexually 

 limited transmission can thus be accounted for. It was fur- 

 ther shown that if a male bird varied by becoming brighter 

 while young, such variations would be of no service until 

 the age for reproduction had arrived, and there was compe- 

 tition between rival males. But in the case of birds living 

 on the ground and commonly in need of the protection of 

 dull colors, bright tints would be far more dangerous to the 

 young and inexperienced than to the adult males. Conse- 

 quently the males which varied in brightness while young 

 would sufEer much destruction and be eliminated through 

 natural selection; on the other hand, the males which varied 



