the sexual organs. We have seen the gradual transition of stamens to
pistils, and of pistils to stamens, the development of ovules on the
edges of the anther, the co-existence of pollen with ovules on an
antheroid body, and, stranger still, the actual development of pollen
within the tissues of the ovule itself! From such facts, in addition to
what we know of the relative position, internal structure, and mode of
development of the organs, it is impossible to avoid coming to the
conclusion that, however distinctly these parts may, under ordinary
circumstances, be set apart for the performance of distinct functions,
morphologically they are homologous.

These ideas may be carried yet farther--the same sort of evidence, which
is adduced in support of the morphological identity of leaves with the
parts of the flower, may be advanced in confirmation of the opinion,
that, morphologically, there is no distinction between axis and leaf.
The leaf, according to this view, is a specialised portion of the axis
set apart to do certain work, just as the petals, stamens, &c., are
leaves told off for distinct uses. It is unnecessary to refer to the
intermediate productions linking the leaf-form to that of the axis, all
that is requisite here is to point out the facts that teratology lends
in support of these views. These may be summed up by the statement that
almost all those attributes which morphologists recognise as peculiar to
one or the other organ respectively, may be and are manifested by both.
We have the stem acquiring the characters of the leaf, and the leaf
those of the stem. Thus we have seen leaves, leaf-buds, branches, and
flower-buds springing from leaves or leaf-organs;[555] see pp. 174, 177,
445, &c. The structure that we are apt to associate exclusively with
one is found to pertain to the other. The arrangement of the vascular
cords in the leaf-organ finds its counterpart in the axis, generally, it
is true, modified to suit altered circumstances or diverse purposes. In
some cases the disposition is absolutely indistinguishable in the two
organs. It may then be said that the distinctions usually drawn between
axis and leaf are not absolute, and that, however necessary such a
separation may be for descriptive or physiological purposes,
morphologically the two organs are identical. Again, it may be said that
leaf and axis are two phases of the same organ,--an organ capable of
existing in its undifferentiated state in th