SEX-CHARACTERS IN EVOLUTION 133 



(c) that the tendency to longer growth is, even when 

 no treatment is applied, distinctly inherited. It is a 

 legitimate and logical conclusion that the inherited 

 tendency is the result of the artificial treatment. 

 No other breed of fowls shows such excessive growth 

 of tail feathers. It may be admitted that individuals 

 differ considerably in their congenital tendency 

 to greater growth, i.e. greater length of the tail 

 feathers, but according to my views this is not 

 contradictory to the main conclusion, for every 

 hereditary character shows individual variation. 



It may be pointed out here that on the Lamarckian 

 theory the conception of adaptations is not teleo- 

 logical : they do not exist for a certain purpose, but 

 are the result of external stimulations arising from 

 the actions and habits of the organism. The latter 

 conception is the more general, for cases of somatic 

 sexual characters exist which cannot be said to have 

 a use or function. For example, the comb and 

 wattles of Oallus are sexually dimorphic, being in the 

 original species larger in the cock than in the hen. 

 There is no convincing evidence that these ap- 

 pendages are either for use or ornament. They are, 

 in fact, a disadvantage to the bird, being used by 

 his adversary to take hold of when he strikes. The 

 first thing that happens when cocks fight is the bleed- 

 ing and laceration of the comb, as they peck at each 

 other's heads. This laceration of the skin is, in my 

 view, the primary cause of the evolution of these 

 structures, leading to hypertrophy. But in this, 

 as in other cases, the hereditary result is regular, 

 constant, and symmetrical, while the immediate 

 effect on the individual is doubtless irregular. 



