hand that works the machine (environment), just as the quality of the
sound produced by a fiddle depends entirely upon the hand which plays
upon it. It would be improper to apply the term "mutation" to those
genetic characters which are not new characters or new variants of old
characters, but such genetic characters are of the same nature as
those characters to which the term mutation has been applied. It may be
noticed in passing that it is very questionable if the modern biologist
has acted in the real interests of science in applying the term mutation
in the sense in which he has applied it. The genetic characters of
organisms come from one of two sources: either they are old characters
and are due to the action of what we call inheritance or they are new
and are due to what we call variation. If the term mutation is applied
to the actual alteration of the machinery of the protoplasm, no
objection can be felt to its use; but if it be applied, as it is, to the
product of the action of the altered machine, viz. to the new genetic
character, it leads to confusion. Inheritance is the persistence of the
structure of the machine; characters are the products of the working of
the machine; variation in genetic characters is due to the alteration
(mutation) in the arrangement of the machinery, while variation in
acquired characters (Lamarckian) is due to differences in the mode of
working the machinery. The machinery when it starts (in the new zygote)
has the power of grinding out certain results, which we call the
characters of the organism. These appear at successive intervals
of time, and the orderly manifestation of them is what we call the
life-history of the organism. This brings us back to the question with
which we started this discussion, viz. what is the relation of these
variations in structure, which successively appear in an organism and
constitute its life-history, to the mutational variations which appear
in different organisms of the same brood or species. The question is
brought home to us when we ask what is a bud-sport, such as a nectarine
appearing on a peach-tree? From one point of view, it is simply a
mutation appearing in asexual reproduction; from another it is one of
these successional characters ("growth variations") which constitute
the life-history of the zygote, for it appears in the same zygote which
first produces a peach. Here our analogy of a machine which only works
in one way seems to fail us