ds have come down to us from the age
of the Pharaohs in the wrappings of the Egyptian mummies,--that they are
widely diffused in the air and the waters, insomuch that no sooner does
a coral reef appear above the level of the sea than it is forthwith
covered with herbage by means of seeds wafted by the winds or deposited
by the waves,--and that it is almost impossible to exclude them by any
artificial expedient, since they are capable of resisting the action of
boiling water and even of alcohol itself,--it cannot, we think, be
denied that the few cases which still remain obscure or unexplained may
be, at least, _probably_ accounted for in accordance with the same
natural law which is found to be invariably established in every
department to which our clear knowledge extends.

In regard, again, to the supposed "transmutation of species," we are
equally warranted in affirming that it is destitute of all experimental
evidence, and unsupported even by any natural analogy. As the doctrine
of spontaneous generation stands opposed to the maxim that _organic life
can be produced only by organic life_, so the doctrine of a
transmutation of species stands opposed to the equally certain maxim
that _like produces like, both in the vegetable and animal kingdoms_.
Cuvier has demonstrated, with reference to the birds and reptiles
preserved in Egypt, an entire fixity and uniformity of species, in
every, even the least, particular, for at least three thousand
years.[48] In the actual course of Nature we see no tendency to change;
nay, a barrier seems to have been erected in the constitution of Nature
itself to prevent the possible confusion of races by promiscuous
intercourse, through that provision which renders the mule incapable of
reproduction. No plant has ever been found in a state of transition from
a lower to a higher form; no instance has ever been produced of one of
the algae being transmuted into the lowest form of terrestrial
vegetation; nor of a small gelatinous body developing itself into a
fish, a bird, or a beast; nor of an ourang-outang rising into a man.[49]
It is true, indeed, 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 arise changes of appearance or structure, and some of
these changes are transmissible to the offspring; but the mutations thus
superinduced are _govern