SEXUAL SELECTION 655 



probable that in nearly the same manner as the constitutional 

 disturbance in the ofEspring, caused by a cross between two 

 distinct species or races, often leads to the reappearance of 

 long -lost characters," so here, the disturbance in the consti- 

 tution of the individual, resulting from castration, produces 

 the same effect. 



The tusks of the elephant, in the diflEerent species or races, 

 differ according to sex, nearly as do the horns of ruminants. 

 In India and Malacca the males alone are provided with 

 well-developed tusks. The elephant of Ceylon is considered 

 by most naturalists as a distinct race, but by some as a dis- 

 tinct species, and here "not one in a hundred is found with 

 tusks, the few that possess them being exclusively males. ' ' "" 

 The African elephant is undoubtedly distinct, and the female 

 has large, well-developed tusks, though not so large as those 

 of the male. 



These differences in the tusks of the several races and 

 species of elephants — the great variability of the horns of 

 deer, as notably in the wild reindeer — the occasional pres- 

 ence of horns in the female Antilope bezoartica, and their 

 frequent absence in the female of Antilocapra americana — 

 the presence of two tusks in some few male narwhals — the 

 complete absence of tusks in some female walruses — are all 

 instances of the extreme variability of secondary sexual 

 characters, and of their liability to differ in closely allied 

 forms. 



Although tusks and horns appear in all cases to have 

 been primarily developed as sexual weapons, they often 

 serve other purposes. The elephant uses his tusks in at- 

 tacking the tiger; according to Bruce, he scores the trunks 

 of trees until they can be thrown down easily, and he like- 

 wise thus extracts the farinaceous cores of palms; in Africa 



" I have given various experiments and other evidence proving that this is 

 the case in my "Variation of Animals and Plants under Domestication," vol. 

 ii, 1868, pp. 39-47. 



*> Sir J. Emerson Tennent, "Ceylon," 1859, vol. ii. p. 274. For Malacca, 

 "Journal of Indian Archipelago," vol. iv. p. 357. 



