did not cease growth till 26th August. On 2nd September the left central
rectrix was almost at the end of its growth, the right had ceased to grow
a little before. The left was about an inch longer than the right. Thus
both in length in duration of growth the feathers of the pulled side were
longer than those of the right, and this was the result of treatment
continued only six months, and commenced some months after the feathers
had begun to grow. I have no doubt, however, that the pulling out of the
feather as soon as it shows signs of forming quill, so that its successor
at once grows again, is even more important in producing the great length
of feather than the stroking of the feather itself.

In this case, then there is no doubt (_a_) that the long-tailed birds are
artificially treated with the utmost care and ingenuity by the Japanese,
who produced them; (_b_) that the mechanical stimulus in my experiments
did cause the feathers to grow for a longer period and attain greater
length; (_c_) that the tendency to longer growth is, even when no
treatment is applied, distinctly inherited. It is a legitimate and logical
conclusion that the inherited tendency is the result of the artificial
treatment. No other breed of fowls shows such excessive growth of tail
feathers. It may be admitted that individuals differ considerably in their
congenital tendency to greater growth, _i.e._ greater length of the tail
feathers, but according to my views this is not contradictory to the main
conclusion, for every hereditary character shows individual variation.

It may be pointed out here that on the Lamarckian theory the conception of
adaptations is not teleological: they do not exist for a certain purpose,
but are the result of external stimulations arising from the actions and
habits of the organism. The latter conception is the more general, for
cases of somatic sexual characters exist which cannot be said to have a
use or function. For example, the comb and wattles of _Gallus_ are