Cn Ar. yni. 
SEXUAL SELECTION. 
287 
and developed in the adult males alone. When, on the 
other hand, the adult male closely resembles the young 
of both sexes (these, with rare exceptions, being alike), 
he generally resembles the adult female ; and in most of 
these cases the variations through which the young and 
old acquired their present characters, probably occurred 
hi conformity with our rule during youth. Lilt there is 
here room for doubt, as characters are sometimes trans- 
ferred to the offspring at an earlier age than that at 
' v hich they first appeared in the parents, so that the 
parents may have varied when adult, and have trans- 
ferred their characters to their offspring whilst young. 
There are, moreover, many animals, in which the two 
• S( -*Xes closely resemble each other, and yet both differ 
from their young ; and here the characters of the adults 
"mst have been acquired late in life ; nevertheless, 
these characters in apparent contradiction to our rule, 
aj e transferred to both sexes. We must not, however, 
° v erlook the possibility or even probability of succes- 
sive variations of the same nature sometimes occurring, 
'"ider exposure to similar conditions, simultaneously in 
hoth sexes at a rather late period of life ; and in this case 
the variations would be transferred to the offspring of 
hoth sexes at a corresponding late age ; and there would 
he no real contradiction to our rule ot the variations 
"’hich occur late in life being transferred exelusiv ely to 
fhe sox in which they first appeared, 'this latter rule 
8e ems to hold true more generally than the second rule, 
finely, that variations which occur in either sex early 
hi life tend to be transferred to both sexes. As it was 
obviously impossible even to estimate in how large a 
"Umber of cases throughout the animal kingdom these 
l ) Vo propositions hold good, it occurred to me to inves- 
%ate some striking or crucial instances, and to rely 
011 the result. 
