of plants had been elicited by as tedious and costly a
process as that by which we now make some slight additional improvements
in certain races, we should have remained to this day in ignorance of
the greater number of their useful qualities.

_Acquired instincts of some animals become hereditary._--It is
undoubtedly true, that many new habits and qualities have not only been
acquired in recent times by certain races of dogs, but have been
transmitted to their offspring. But in these cases it will be observed,
that the new peculiarities have an intimate relation to the habits of
the animal in a wild state, and therefore do not attest any tendency to
a departure to an indefinite extent from the original type of the
species. A race of dogs employed for hunting deer in the platform of
Sante Fa, in Mexico, affords a beautiful illustration of a new
hereditary instinct. The mode of attack, observes M. Roulin, which they
employ consists in seizing the animal by the belly and overturning it by
a sudden effort, taking advantage of the moment when the body of the
deer rests only upon the fore-legs. The weight of the animal thus thrown
over is often six times that of its antagonist. The dog of pure breed
inherits a disposition to this kind of chase, and never attacks a deer
from before while running. Even should the deer, not perceiving him,
come directly upon him, the dog steps aside and makes his assault on the
flank; whereas other hunting dogs, though of superior strength, and
general sagacity, which are brought from Europe, are destitute of this
instinct. For want of similar precautions, they are often killed by the
deer on the spot, the vertebrae of their neck being dislocated by the
violence of the shock.[817]

A new instinct has also become hereditary in a mongrel race of dogs
employed by the inhabitants of the banks of the Magdalena almost
exclusively in hunting the white-lipped pecari. The address of these
dogs consists in restraining their ardor, and attaching themselves to no
animal in particular, but keeping the whole herd in check. Now, among
these dogs some are found, which the very first time they are taken to
the woods, are acquainted with this mode of attack; whereas, a dog of
another breed starts forward at once, is surrounded by the pecari, and,
whatever may be his strength, is destroyed in a moment.

Some of our countrymen, engaged of late in conducting one of the
principal mining associations in Mexico, th