in the peculiar manner of flight of certain breeds of the pigeon,
&c. We have analogous cases with mankind in the inheritance
of tricks or unusual gestures, to which we shall presently recur.
To those who admit the gradual evolution of species,
a most striking instance of the perfection with which the most
difficult consensual movements can be transmitted, is afforded
by the humming-bird Sphinx-moth (_Macroglossa_); for this moth,
shortly after its emergence from the cocoon, as shown by the bloom
on its unruffled scales, may be seen poised stationary in the air,
with its long hair-like proboscis uncurled and inserted
into the minute orifices of flowers; and no one, I believe,
has ever seen this moth learning to perform its difficult task,
which requires such unerring aim.


[2] Muller, `Elements of Physiology,' Eng. translat. vol. ii. p. 939.
See also Mr. H. Spencer's interesting speculations on the
same subject, and on the genesis of nerves, in his `Principles
of Biology,' vol. ii. p. 346; and in his `Principles of Psychology,'
2nd edit. pp. 511-557.

When there exists an inherited or instinctive tendency to the performance
of an action, or an inherited taste for certain kinds of food,
some degree of habit in the individual is often or generally requisite.
We find this in the paces of the horse, and to a certain extent
in the pointing of dogs; although some young dogs point excellently
the first time they are taken out, yet they often associate the proper
inherited attitude with a wrong odour, and even with eyesight.
I have heard it asserted that if a calf be allowed to suck its mother
only once, it is much more difficult afterwards to rear it by hand.[3]