24 THE STORY OF THE BIRDS. 
the toucans, perhaps), have their bodies solidly cov- 
ered. But the embryos (which may tell us so much 
of the history of the race) in the ostrich forms have 
the feather tracts well defined, and so have some fos- 
sil penguins. We are justified, then, in thinking that 
the primitive birds had their plumage in patches. 
_ The wise men tell us that feathers are modified 
scales, and it may be that these modifications had 
different centers or places of beginning; but since 
the patterns now show so much variety, it is evident 
that the original arrangements have been very striking- 
ly changed somewhere in the Jess remote past. But 
why these patterns should tend now to prevail so dis- 
tinctly, and to be rather more than less definite in the 
higher groups, is not so apparent. It may be that 
after the plumage grew longer and spread well over 
the entire surface from different centers, as it does 
now, these bare tracts were all protected from any 
external influence tending to change them, and they 
persist now unmodified. Since solidly feathered birds 
are largely degenerate and flightless, we can not resist 
feeling that bare tracts are in some undefinable way 
connected with flight. At any rate, if we knew why 
a bird cut its frock so, we should certainly know a 
great deal more about why it put on soft raiment and 
about its history in general—just as the fashions of a 
people help us to judge of its customs and character. 
