S64 THE DESCMT of man. 



adult female; and in most of these cases the variations 

 through which the young and old acquired their present 

 cliaracters, probably occurred, according to our rule, during 

 youth. But there is here room for doubt, for characters 

 are sometimes transferred to the offspring at an earlier age 

 than that at which they first appeared in the parents, so 

 that the parents may have varied when adult and have 

 transferred their characters to their offspring while young. 

 There are, moreover, many animals in which the two sexes 

 closely resemble each other, and yet both differ from their 

 young; and here the characters of the adults must have 

 been acquired late in life; nevertheless, these characters, in 

 apparent contradiction to our rule, are transferred to both 

 sexes. We must not, however, overlook the possibility or 

 even probability of successive variations of the same nature 

 occurring, under exposure to similar conditions, simul- 

 taneously in both sexes at a rather late period of life; and 

 in this case the variations would be transferred to the off- 

 spring of both sexes at a corresponding late age; and there 

 would then be no real contradiction to the rule that varia- 

 tions occurring late in life are transferred exclusively to the 

 sex in which they first appeared. This latter rule seems to 

 hold true more generally than the second one, namely, that 

 variations which occur in either sex early in life tend to be 

 transferred to both sexes. As it was obviously impossible 

 even to estimate in how large a number of cases throughout 

 the animal kingdom these two propositions held good, it 

 occurred to me to investigate some striking or crucial 

 instances and to rely on the result. 



An excellent case for investigation is afforded by the 

 deer family. In all the species but one the horns are 

 developed only in the males, though certainly transmitted 

 through the females and capable of abnormal development 

 in them. In the reindeer, on the other hand, the female 

 is provided with horns; so that in this species the horns 

 ought, according to our rule, to appear early in life, long 

 before the two sexes are mature and have come to differ 

 much in constitution. In all the other species the horns 

 ought to appear later in life, which would lead to their 

 development in that sex alone in which they first appeared 

 in the progenitor of the whole family. Now in seven 

 species belonging to distinct sections of tlie family and 

 inhabiting different regions in which the stags alone bear 



