Fixedness of character, or the strength of inheritance, has often been
judged of by the preponderance of certain characters in the crossed
offspring between distinct races; but prepotency of transmission here comes
into play, and this, as we shall immediately see, is a very different
consideration from the strength or weakness of inheritance. It has often
been observed[136] that breeds of animals inhabiting wild and mountainous
countries cannot be permanently modified by our improved breeds; and as
these latter are of modern origin, it has been thought that the greater
antiquity of the wilder breeds has been the cause of their resistance to
improvement by crossing; but it is more probably due to their structure and
constitution being better adapted to the surrounding conditions. When
plants are first subjected to culture, it has been found that, during
several generations, they transmit their characters truly, that is, do not
vary, and this has been attributed to ancient characters being strongly
inherited; but it may with equal or greater probability be consequent on
changed conditions of life requiring a long time for their accumulative
action. Notwithstanding these considerations, it would perhaps be rash to
deny that characters become more strongly fixed the longer they are
transmitted; but I believe that the proposition resolves itself into
this,--that all characters of all kinds, whether new or old, tend to be
inherited, and that those which have already withstood all counteracting
influences and been truly transmitted, will, as a general rule, continue to
withstand them, and consequently be faithfully inherited.

{65}

_Prepotency in the Transmission of Character._

When individuals distinct enough to be recognised, but of the same family,
or when two well-marked races, or two species, are crossed, the usual
result, as stated in the previous chapter, is, that the offspring in the
first generation are intermediate between their parents, or resemble one
parent in one part and the other parent in another part. But this is by no
means the invariable rule; for in many cases it is found that certain
individuals, races, and species are prepotent in transmitting their
likeness. This subject has been ably discussed by Prosper Lucas,[137] but
is rendered extremely complicated by the prepotency sometimes running
equally in both sexes, and sometimes more strongly in one sex than in the
other; it is likewise complicated by