46
Scientific Memoirs by Medical Officers of the Army of India.
and here the tendency, of course, is to pollination of both edges of one of the stigmas of the styles, the other
stigma being protected by its internal situation. This arrangement is comparatively rare. It is to be
understood that the above statements are to be taken generally. They refer merely to the two types of
arrangement. In almost every case neither one nor the other is thoroughly carried out throughout any
flower, and a certain amount of pollination of almost every stigmatic surface occurs. The number of styles
and anthers in individual flowers varies very considerably.
The following table shows the numbers of them present in 9 flowers examined in regard to this point
at different times:—
No. of Plower.
Stamens.
Styles.
1 .
.
. . .
7
5
2
. . . . .
7
5
3
. . . . .
6
6
. 4
. . . . .
5
7
5
. . . . .
6
6
6
.
. . .
.
1 0
10
7
. . . . .
9
8
8
. . . . .
9
1 0
9
. . .
.
.
9
10
Note D.—On the Characters of the Pollen Grains in Ottelia, and on the Phenomena of their Germination.
(Plate VI, Figs. 4, 5.)
The pollen grains in Ottelia are spherical, with an average diameter of 0.66 m.m. They are covered
with minute tubercles, and are of a fine yellow colour due to the contained protoplasm. The protoplasm
is coarsely granular, and the colouring matter is primarily evenly diffused throughout it. During germin-
ation, however, it tends to separate in the form of distinct oily drops, which frequently exude through the
cell wall and sometimes pass outwards along the germinating tubes. During germination the pollen grains
are precisely like germinating spores of uredinal fungi, save that two nuclei are readily revealed within them
under the influence of appropriate staining reagents. Of these I have found picrocarmine to be the most
satisfactory. It colours the cytoplasm yellow and the nucleoplasm a fine red. The nuclei differ conspicu-
ously from one another in form as a rule, one being of an elongated cylindrical shape, with rounded extre-
mities; the other shorter and irregularly rounded in outline. During the progress of germination both of
them appear ultimately to leave the interior of the grains, but, as a rule, at considerable intervals, and the
cylindrical one appearing normally to be the first to do so.
Note E.—On the Structure of the Leaves in Ottelia.
The lamina in the normal submerged leaves in Ottelia is entirely devoid of stomata or pseudostomata.
The superior and inferior epidermis (Plate VII, Fig. 2, 3) each consists of a single row of cells. They are
connected at wide intervals with one another by means of partitions consisting also of single strata of cells,
and in certain sites perforated by numerous intercellular spaces. The cell walls around these spaces
are, as a rule, as in the case of the porous partitions of the petioles, scapes, and stems, specially thickened,
and, as revealed by staining reagents, also differ from those in other places in the quality of their component
materials. Both of these phenomena are apparently related to maintaining the patency of the openings.
The rest of the lamina, apart from the sparsely distributed vascular bundles, is composed of a great
system of huge intercellular spaces. The contents of these are different under the influence of different con-
ditions. When the leaves have been removed from the access of light for some time, the spaces attain their
minimum capacity and are occupied by liquid. Under the influence of sunlight an accumulation of
gaseous bubbles occurs within them. These bubbles gradually melt into one another, and many spaces thus
ultimately come to be occupied by one huge bubble which fills their entire cavity and causes the upper and
under epidermal boundaries to bulge outwards (vide Plate VII, Fig. 6, a, b).B o t h t h e e p i d e r m a l a n d
parenchymal cells contain networks of active protoplasm along which the numerous chlorophyll corpuscles
are carried from one part of the cell cavity to another.