SUMMARY. 
237 
C«. 
; 4P. XVI. 
lesion, then if the parents vary late in life — and we 
0c ° w that this constantly occurs with our poultry, and 
c asionally with other birds — the young will be left 
^affected, whilst the adults of both sexes will be 
.'i 'fled. If both these laws of inheritance prevail and 
j 1, ‘ r sex varies late in life, that sex alone will be 
'hilled, the other sex and the young being left un- 
( ‘ lw; ted. When variations in brightness or in other 
“•pbuon. characters occur early in life, as no doubt 
. <jl1 happens, they will not be acted on through sexual 
f Action until the period of reproduction arrives ; eonse- 
l llt! ntly they will, if dangerous to the young, be elimi- 
cte d through natural selection. Thus we can under- 
llc j how it is that variations arising late in life have 
°ften been preserved for the ornamentation of the 
ales- the females and the young being left almost un- 
^ e cted, and therefore like each other. With species 
^riiig a distinct summer and winter plumage, the males 
^ ' y bich either resemble or differ from the females 
^ llQ g both seasons or during the summer aloue, the 
s=?ees and kinds of resemblance between the young 
, ' the old are exceedingly complex; and this com- 
j. exj ty apparently depends on characters, first acquired 
r |- ^he males, being transmitted in various ways and 
e l 'ces, as limited by age, sex, and season. 
the young of so many species have been but little 
quilled in colour and in other ornaments, we are 
Jj^Ued to form some judgment with respect to the 
^’ttnage of their early progenitors ; and we may infer 
a t tUe beauty of our existing species, if wo look to the 
0 j.'° e class, has been largely increased since that period 
lv "hieh the immature plumage gives us an indirect 
c ord. Many birds, especially those which live much 
the ground, have undoubtedly been obscurely co- 
0| ii'ed 
for the sake of protection. In some instances 
