By ee ee? | Panag he 
ae Se A ee ee N 
1884.] Zoölogy . 545 
The principal reasons for this being, first, that it does not require 
for its production a correlative diversification of adjacent features. 
of the surrounding tissues and adjoining parts, thus requiring 
more time, energy, and force than a mere slight change of the 
color-secreting tissue. Second, as it is comparatively so easily 
affected, it has been subject to more of the passing whims and 
ies of mankind than any other part, especially as it does not 
pie the patience necessary to produce a change of form or 
re 
tation of his selective inclination. Being so susceptible to 
variation from the parental marking and coloring, it is also the 
part in which we should expect atavism to occur most frequently, 
as is the fact, 
As a theoretical illustration we will represent the development 
of a domesticated bird, from the beginning of life in the egg to 
the ult, by A to Y a, which will represent the young, and Za 
adult, a representing coloration. And a variety produced by 
7 Selection from the parent stock by Z z 6(z form, 4 color). 
1 ġ will, of course, have to pass through the same embryologi- 
nes? as Z a, because it was derived from that stock. 
is we regard the different variations of form of the species 
ugh which a variety passed before reaching its present char- 
roe it is rising to the peculiarities of the next or adult form, we 
ù perceive “Sop those special germs whose further sce 
rested will simply m i i tures without fur- 
ther evolution Pty mature with the prior fea 
. 
har pating to our illustration again, with Z z 4, we will suppose 
me abnormal condition an arresting of that feature most 
ty ae Teach the original preparental characteristic coloration 
if Wis . to the special varietal characteristics at X; now, 
Previous parent stock, and before the peculiarities 
© parentage have had an opportunity to domi- 
: “id i ile the tendency is 
of raed the May continue to mature while cy 
Yatious Parts commence to develop at different times, a check 
