Quite on the contrary
the facts that strike us most forcibly as being reversions are those
that are apt to give us an insight into the systematic affinity of a
higher degree. We are disposed to make use of them in our attempts to
perfect the natural system and to remould it in such a way as to become
a pedigree of the related groups. Such cases of atavism no doubt occur,
but the anomalies referred to them must be interpreted merely on the
ground of our assumptions as to the relative places in the system to be
assigned to the different forms.
Though such instances cannot be considered as belonging strictly to the
subject we are dealing with, I think it may be as well to give an
example, especially as it affords an occasion for referring to the
highly important researches of Heinricher on the variability and
atavistic [173] tendencies of the pale blue flag or _Iris pallida_. The
flowers of the blue flags have a perianth of six segments united below
into a tube. The three outer parts are dilated and spreading, or
reflexed, while the three inner usually stand erect, but in most species
are broad and colored like the outer ones. Corresponding to the outer,
perianth-segments are the three stamens and the three, petal-like
divisions of the style, each bearing a transverse stigma immediately
above the anther.
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