120 SEXUAL DIMORPHISM 



mate took no notice of her. In this way the polygamy of 

 the jungle fowl and pheasant tribe doubtless arose, the males 

 after a time having entirely abandoned the care of their pro- 

 geny. It is impossible to say what determined the greater 

 domesticity or pugnacity in male or female ; it is sufficient to 

 attribute it to the principle which Herbert Spencer calls the 

 instability of the homogeneous. Among the various forms of 

 Gallinacei there are some in which males and females are 

 equally peaceful and attentive to their families, some in which 

 the males are more so than the females, and some in which 

 the females are more so than the males. To my mind the 

 important point is that difference of size and structure cor- 

 respond to difference of habit, and only manifests itself in 

 the individual when the breeding habits come into play. In 

 the species of Turnix the young females are similar to the 

 adult males. I think it is evident from these facts that the 

 slight peculiarities of plumage in the adult female Turnix 

 must be due to the conditions of life, although the physio- 

 logical explanation is yet to be found. It is possible, as I 

 have suggested in the case of fishes, that the continual sexual 

 excitement produces a nervous influence on the secretion of 

 pigment in the skin and feathers. In the Spanish Bustard 

 Quail, Turnix sylvatica, and some other species the difference 

 in the colour and markings between the sexes is very slight, 

 while in several Australian species there is no difference 

 except in size. 



It would be interesting to know what kind of wounds the 

 females inflict on one another in their combats, and on what 

 parts they are commonly inflicted. No modifications like 

 those which I have attributed in other species to wounds or 

 blows exist in Turnix, although the females are so pugnacious. 

 Probably one reason of this is that the pugnacity of the 

 females has but recently arisen in the evolution of the genus, 

 but it may be that the wounds inflicted are not very severe. 



