INHERITANCE, LIMITED BY AGE. 
183 
Ci, 
Ap - XVI. 
CHAPTER XYI. 
Birds — concluded. 
'^mature plumage in relation to the character of the pi uniage 
lri both sexes when adult — Six classes of cases — Sexual differ- 
e Dces between the males of closcdy-nllied or representative species 
~~ Pie female assuming the characters of the male — Plumage of 
16 young in relation to the summer and winter plumage of the 
adults — On the increase of beauty in the Birds of the World — 
r °tecti vo colouring — Conspicuously-coloured birds — Novelty 
appreciated — Summary of the four chapters on Birds. 
^ 13 'Rust now consider the transmission of characters 
•| S | Suited by age in reference to sexual selection. 
. 16 truth and importance of the principle of inheri- 
ts Ce ^responding ages need not here be discussed, 
. ( ; tl0, igh has already been said on the subject. Before 
f , ' lu g the several rather complex rules or classes of 
l‘ ast ' s > under which all the differences in plumage 
H:t 'v een t p e youn ~ an( j p) ie 0 ld, as far as known to 
*he, J ° 
! > joay be included, it will be well to make a few 
e Vinary remarks. 
" ith animals of all kinds when the young differ in 
°Ur from the adults, and the colours of the former 
are 
far as we can see, of any special service, they 
a - v generally be attributed, like various embryological 
f pictures, to the retention by the young of the character 
a u early progenitor. But this view can be maintained 
C | confidence, only when the young of several species 
ot ° 8el y resemble each other, and likewise resemble 
Ij. er adult species belonging to the same group; for 
{] ? Matter are the living proofs that such a state ol 
ltl gs was formerly possible. Young lions and pumas 
