question of the stability of species as
well as on the origin of species. Professor Morgan, in his {216}
article on Darwinism in the "Light of Modern Criticism," already
quoted, says the important fact (with regard to Mendel's Law) from the
point of view of the theory of evolution is that "the new species have
sprung fully armed from the old ones, like Minerva from the head of
Jove." "From de Vries's results," he adds, "we understand better how
it is that we do not see new forms arising, because they appear, as it
were, fully equipped over night. Old species are not slowly changed
into new ones, but a shaking up of the old organization takes place
and the egg brings forth a new species. It is like the turning of the
kaleidoscope, a slight shift and the new figure suddenly appears. It
needs no great penetration to see that this point of view is entirely
different from the conception of the formation of new species by
accumulating individual variations, until they are carried so far that
the new form may be called a new species."

With regard to this question of the transformation of one species into
another, Mendel himself, in the concluding paragraphs of his article
on hybridization, seems to agree with the expressions of Morgan. He
quotes Gaertner's opinion with apparent approval: "Gaertner, by the
results of these transformation experiments was led to oppose the
opinion of those naturalists who dispute the stability of plant
species and believe in a continuous evolution of vegetation. He
perceives in the complete transformation of one species into another
an indubitable proof that {217} species are fixed within limits beyond
which they cannot change." "Although this opinion," adds Mendel,
"cannot be unconditionally accepted, we find, on the other hand, in
Gaertner's experiments a noteworthy confirmation of that supposition
regarding the variability of cultivated plants which has already been
expressed." This expression of opinion is not very definite, and
Bateson, in what Professor Wilson of Columbia calls his "recent
admirable little book on Mendel's principles," adds the following note
that may prove of service in elucidating Mendel's meaning, as few men
have entered so fully into the understanding of Mendel's work as
Bateson, who introduced him to the English-speaking scientific public,
"The argument of this paragraph appears to be that though the general
mutability of natural species might be doubtful, yet among