tness of its legs, could not fail to be
observed; and the fact that its offspring were similarly short-legged,
and had a consequent inability to get over fences, would inevitably
become widely known. Similarly with plants. That this flower had an
extra number of petals, that that was unusually symmetrical, and that
another differed considerably in colour from the average of its kind,
would be easily seen by an observant gardener; and the suspicion that
such anomalies are inheritable having arisen, experiments leading to
further proofs that they are so, would frequently be made. But it is not
thus with functionally-produced modifications. The seats of these are in
nearly all cases the muscular, osseous, and nervous systems, and the
viscera--parts which are either entirely hidden or greatly obscured.
Modification in a nervous centre is inaccessible to vision; bones may be
considerably altered in size or shape without attention being drawn to
them; and, covered with thick coats as are most of the animals open to
continuous observation, the increases or decreases in muscles must be
great before they become externally perceptible.

A further important difference between the two inquiries is that to
ascertain whether a fortuitous variation is inheritable, needs merely a
little attention to the selection of individuals and the observation of
offspring; while to ascertain whether there is inheritance of a
functionally-produced modification, it is requisite to make arrangements
which demand the greater or smaller exercise of some part or parts;
and it is difficult in many cases to find such arrangements, troublesome
to maintain them even for one generation, and still more through
successive generations.

Nor is this all. There exist stimuli to inquiry in the one case which do
not exist in the other. The money-interest and the interest of the
fancier, acting now separately and now together, have prompted
multitudinous individuals to make experiments which have brought out
clear evidence that fortuitous variations are inherited. The
cattle-breeders who profit by producing certain shapes and qualities;
the keepers of pet animals who take pride in the perfections of those
they have bred; the florists, professional and amateur, who obtain new
varieties and take prizes; form a body of men who furnish naturalists
with countless of the required proofs. But there is no such body of men,
led either by pecuniary interest or the interest o