r les vraies fleurs doubles chez les
Orchidees," 'Bull. Acad. Roy. Belg.,' vol. xix, part ii, 1852. p. 171.

[307] C. Morren, 'Bull. Acad. Belg.,' vol. xx, 1853, part ii, p. 284
(_Syringa_).

[308] 'Rep. Bot. Congress,' London, 1866, p. 135, t. vii, f. 14.

[309] Although it is generally admitted that the filament of the stamen
corresponds to the stalk of the leaf, and the anther to the leaf-blade,
yet there are some points on which uncertainty still rests. One of these
is as to the sutures of the anther. Do these chinks through which the
pollen escapes correspond (as would at first sight seem probable) to the
margins of the antheral leaf, or do they answer to the lines that
separate the two pollen-cavities on each half of the anther one from the
other? Professor Oliver, 'Trans. Linn. Soc.,' vol. xxiii, 1862, p. 423,
in alluding to the views held by others on this subject, concludes, from
an examination of some geranium flowers in which the stamens were more
or less petaloid, that Bischoff's notion as to the sutures of the anther
is correct, viz., that they are the equivalents of the septa of
untransformed tissue between the pollen-sacs. Some double fuchsias
('Gard. Chron.,' 1863, p. 989) add confirmation to this opinion. In
these flowers the petals were present as usual, but the stamens were
more or less petaloid, the filaments were unchanged, but the anthers
existed in the form of a petal-like cup from the centre of which
projected two imperfect pollen-lobes (the other two lobes being
petaloid). Now, in this case, the margins of the anther were coherent to
form the cup, and the pollen was emitted along a line separating the
polliniferous from the petaloid portion of the anther. This view is also
borne out by the double-flowered _Arbutus Unedo_, and also by what
occurs in some double violets, wherein the anther exists in the guise of
a broad lancet-shaped expansion, from the surface of which project four
plates (fig. 157), representing apparently the walls of the pollen-sacs,
but destitute of pollen; the chink left between these plates corresponds
thus to the suture of the normal anther.

[Illustration: FIG. 157.--Petaloid stamen of _Viola_, with four
projecting plates.]

The inner or upper portion of the anther-leaf is that which is most
intimately concerned in the formation of pollen; it comparatively rarely
(query ever) happens that the back or lower surface of the antheral leaf
is specially devoted to the form