cial bones,
and the consequent want of space; and the shortening results from a
peculiar and abnormal state of the basal cartilages of the bones.

_Relative Position of Flowers with respect to the Axis, and of Seeds in the
Capsule, as inducing Variation._

In the thirteenth chapter various peloric flowers were described, and
their production was shown to be due either to arrested development, or
to reversion to a primordial condition. Moquin-Tandon has remarked that
the flowers which stand on the summit of the main stem or of a lateral
branch are more liable to become peloric than those on the sides;[856]
and he adduces, amongst other instances, that of _Teucrium
campanulatum_. In another Labiate plant grown by me, viz. the
_Galeobdolon luteum_, the peloric flowers were always produced on the
summit of the stem, where flowers are not usually borne. In
Pelargonium, a _single_ flower in the truss is frequently peloric, and
when this occurs I have during several years invariably observed it to
be the central flower. This is of such frequent occurrence that one
observer[857] gives the names of ten varieties flowering at the same
time, in every one of which the central flower was peloric.
Occasionally more than one flower in the truss is peloric, and then of
course the additional ones must be lateral. These flowers are
interesting as showing how the whole structure is correlated. In the
common Pelargonium the upper sepal is produced into a nectary which
coheres with the flower-peduncle; the two upper petals differ a little
in shape from the three lower ones, and are marked with dark shades of
colour; the stamens are graduated in length and upturned. In the
peloric flowers, the nectary aborts; all the petals become alike both
in shape and colour; the stamens are generally reduced in number and
become straight, so that the whole flower resembles that of the allied
genus Erodium. The correlation between these changes is well shown when
one of the two upper petals alone loses its dark mark, for in this case
the nectary does not entirely abort, but is usually much reduced in
length.[858]

{346}

Morren has described[859] a marvellous flask-shaped flower of the
Calceolaria, nearly four inches in length, which was almost completely
peloric; it grew on the summit of the plant, with a normal flower on