Chap. VIII.] SEXUAL SELECTION. 273 



Inheritance at Corresponding Seasons of the Year. — 

 With animals in a state of nature innumerable instances 

 occur of characters periodically appearing at different sea- 

 sous. We see this with the horns of the stag, and with 

 the fur of arctic animals which becomes thick and white 

 during the winter. Numerous birds acquire bright colors 

 and other decorations during the breeding-season alone. I 

 can throw but little light on this form of inheritance from 

 facts observed under domestication. Pallas states 21 that, in 

 Siberia, domestic cattle and horses periodically become 

 lio-hter-colored during the winter; and I have observed a 

 similar marked change of color in certain ponies in Eng- 

 land. Although I do not know that this tendency to as- 

 sume a differently-colored coat during different seasons of 

 the year is transmitted, yet it probably is so, as all shades 

 of color are strongly inherited by the horse. Nor is this 

 form of inheritance, as limited by'season, more remarkable 

 than inheritance as limited by age or sex. 



| 



Inheritance as Limited by Sex. — The equal transmis- 

 sion of characters to both sexes is the commonest form of 

 inheritance, at least with those animals which do not pre- 

 sent strongly-marked sexual differences, and indeed with 

 many of these. But characters are not rarely transferred 

 exclusively to that sex, in which they first appeared. 

 Ample evidence on this head has been advanced in my 

 work on Variation under Domestication; but a few in- 

 stances may here be given. There are breeds of the sheep 

 and goat, in which the horns of the male differ greatly in 

 shape from those of the female ; and these differences, ac- 

 quired under domestication, are regularly transmitted to 



21 ' Novae species Quadrupedum e Glirium ordine,' 1778, p. 7. On the 

 transmission of color by the horse, see ' Variation of Animals, etc., under 

 Domestication,' vol. i. p. 21. Also vol. ii. p. 71, for a general discussion 

 on Inheritance as limited by Sex. 



