acacia_; he
states that if a cutting or a graft be taken from the upper portion of
the tree, the fastigiate habit will be reproduced, and the branches will
be furrowed and covered with short prickles; but if the plant be
multiplied by detaching portions of the root-stock, then instead of
getting a pyramidal tree with erect branches, a spreading bushy shrub is
produced, with more or less horizontal, cylindrical branches, destitute
of prickles.[212]

=Eversion of the axis.=--In the case of the fig, the peculiar
inflorescence is usually explained on the supposition that the
termination of the axis becomes concave, during growth, bearing the true
flowers in the hollow thus formed. The cavity in this case would
probably be due not to any real process of excavation, but to a
disproportionate growth of the outer as contrasted with the central
parts of the fig. Some species of _Sempervivum_ have a similar mode of
growth, so that ultimately a kind of tube is formed, lined by the
leaves, the central and innermost being the youngest. The hip of the
Rose may be explained in a similar manner by the greater proportionate
growth of the outer as contrasted with the central portions of the apex
of the flower-stalk. In cases of median prolification, already referred
to, the process is reversed, the central portions then elongate into a
shoot and no cavity is formed. A fig observed by Zuccarini (figs. 105,
106) appears to have been formed in a similar manner, the flower-bearing
summit of the stalk not being contracted as usual, the flowers projected
beyond the orifice of the fig. If this view be correct the case would be
one rather of lengthening of the axis than of absolute eversion since it
was never inverted.

[Illustration: FIG. 105.--Fig showing prolonged inflorescence and
projecting flowers.]

[Illustration: FIG. 106.--Section of the same.]

=Altered direction of leaves.=--The leaves partake more or less of the
altered direction of the axis, as in fastigiate elms, but this is not
universally the case, for though the stem is bent downwards the leaves
may be placed in the opposite direction; thus in some specimens of
_Galium Aparine_ growing on the side of a cliff from which there had
been a fall of chalk, the stems, owing apparently to the landslip, were
pendent, but the leaves were abruptly bent upwards.

One of the most singular instances of an inverted direction of the
leaves is that presented by a turnip (fig. 107) presente