mand an explanation
widely different from that which might account for the extremely slow
and slight inheritance of the normal effects of use and disuse? Surely
it would be better to suspend one's judgment as to the true explanation
of highly exceptional and purely pathological cases rather than resort
to an hypothesis that creates more difficulties than it solves.

THE MOTMOT'S TAIL.

The narrowing of the long central tail feathers of the motmot is
attributed to the inherited effects of habitual mutilation (_Descent of
Man_, pp. 384, 603). But in the specimens at South Kensington[61] the
narrowness extends upwards much beyond the habitually denuded part, and
the broadened end is the broadest part of the whole feather. If the
inherited effect of an inch or two of denudation extends from three to
six inches upwards, why has it not also extended two inches downwards so
as to narrow the broadened end? The narrowness seems to be a mainly
relative or negative effect produced by the broadening out of a long
tapering feather at its end under the influence of sexual selection.
Several other birds have similarly narrowed or spoon-shaped feathers and
do not bite them. Is it not more feasible to suppose that this
attractive peculiarity first suggested its artificial intensification,
than to suppose that the bird began nibbling without any definite cause?
Sexual selection would then encourage the habit. Anyhow, it is as
impossible to show that the mutilation preceded the narrowing as it is
to show that tonsure preceded baldness.

OTHER INHERITED INJURIES MENTIONED BY DARWIN.

Darwin quotes some cases from Dr. Prosper Lucas's "long" but weak and
unsatisfactory "list of inherited injuries."[62] But Lucas was somewhat
credulous. One of his cases is that many girls were born in London
without mammae through the injurious effect of certain corsets on the
mothers. He also gives a long account of a Jew who could read through
the thick covers of a book, and whose son inherited this "hyperaesthesia"
of the sense of sight in a still more remarkable degree (i. 113-119).
Evidently Lucas's cases cannot be accepted without some amount of
reserve.

The cases of the three calves which inherited the one-horned condition
of the cow, the two sons who inherited a father's crooked finger, and
the two sons who were microphthalmic on the same side as their father
had lost an eye, may be due to mere coincidence; or an inherited
constitutional te