The Descent of Man

in separate pens. With the Polish breeds the
bony protuberance of the skull which supports
the crest is partially developed even before the
chickens are hatched, and the crest itself soon
begins to grow, though at first feebly (47. For
full particulars and references on all these
points respecting the several breeds of the
Fowl, see 'Variation of Animals and Plants under
Domestication,' vol. i. pp. 250, 256. In regard
to the higher animals, the sexual differences
which have arisen under domestication are
described in the same work under the head of
each species.); and in this breed the adults of
both sexes are characterised by a great bony
protuberance and an immense crest.
Finally, from what we have now seen of the
relation which exists in many natural species
and domesticated races, between the period of
the development of their characters and the
manner of their transmission—for example, the
striking fact of the early growth of the horns in