natural causes, be made to pass from the type of one species to that of
another. A wolf by domestication, for example, can never become a dog,
nor the ourang-outang by the force of external circumstances be brought
within the circle of the human species.

In this opinion Mr. LYELL, Dr. PRICHARD, and Mr. LAWRENCE, concur. The
general conclusion at which they have arrived is, that there is a
capacity in all species to accommodate themselves to a certain extent to
a change of external circumstances; this extent varying greatly
according to the species. There may thus be changes of appearance or
structure, and some of these changes are transmissible to the offspring;
but the mutations thus superinduced are governed by certain laws, and
confined within certain limits. Indefinite divergence from the original
type is not possible, and the extreme limit of possible variation may
usually be reached in a short period of time; in short, Professor
WHEWELL concludes (_Indications of Creation_, p. 56), _that every
species has a real existence in nature_, and a transmutation from one to
another does not exist. Thus for example, CUVIER remarks that,
notwithstanding all the differences of age, appearance and habits, which
we find in the dogs of various races and countries, and though we have
(in the Egyptian mummies) skeletons of this animal as it existed 3,000
years ago, the relation of the bones to each other remains essentially
the same; and with all the varieties of their shape and size, there are
characters which resist all the influences, both of external nature, of
human intercourse, and of time.

What varieties, again, in the forms of the different breeds of horses
and horned cattle; racers, hunters, coach horses, dray horses, and
ponies; short-horns and long-horns, Devons and Herefords, polled
galloways and Shetlands; how unlike are the unimproved breeds of cattle