312 THE DESCENT OF MAN 



We liave as yet considered the transference of characters, 

 relatively to their period of development, only in species in 

 a natural state; we will now turn to domesticated animals, 

 and'first touch on monstrosities and diseases. The presence 

 of supernumerary digits, and the absence of certain pha- 

 langes, must be determined at an early embryonic period — 

 the tendency to profuse bleeding is at least congenital, as is 

 probably color-blindness — yet these peculiarities, and other 

 similar ones, are often limited in their transmission to one 

 sex; so that the rule that characters developed at an early 

 period tend to be transmitted to both sexes, here wholly 

 fails. But this rule, as before remarked, does not appear 

 to be nearly so general as the converse one, namely, that 

 characters which appear late in life in one sex are trans- 

 mitted exclusively to the same sex. From the fact of the 

 above abnormal peculiarities becoming attached to one sex 

 long before the sexual functions are active, we may infer 

 that there must be some difference between the sexes at 

 an extremely early age. With respect to sexually limited 

 diseases, we know too little of the period at which they 

 originate, to draw any safe conclusion. Gout, however, 

 seems to fall under our rule, for it is generally caused by 

 intemperance during manhood, and is transmitted from the 

 father to his sons in a miich more marked manner than to 

 his daughters. 



In the various domestic breeds of sheep, goats, and 

 cattle, the males differ from their respective females in 

 the shape or development of their horns, forehead, mane, 

 dewlap, tail, and hump on the shoulders; and these pecu- 

 liarities, in accordance with our rule, are not fully developed 

 until a rather late period of life. The sexes of dogs do not 

 differ, except that in certain breeds, especially in the Scotch 

 deer-hound, the male is much larger and heavier than the 

 female; and, as we shall see in a future chapter, the male 

 goes on increasing in size to an unusually late period of 

 life, which, according to rule, will account for his increased 

 size being transmitted to his male offspring alone. On the 



