above it, and is thus externally visible. It stands high above the anthers,
which are situated halfway down the tube and cannot be easily seen. In the
short-styled form the anthers are attached near the mouth of the tube, and
therefore stand above the stigma, which is seated in about the middle of the
tubular corolla. The corolla itself is of a different shape in the two forms;
the throat or expanded portion above the attachment of the anthers being much
longer in the long-styled than in the short-styled form. Village children notice
this difference, as they can best make necklaces by threading and slipping the
corollas of the long-styled flowers into one another. But there are much more
important differences. The stigma in the long-styled form is globular; in the
short-styled it is depressed on the summit, so that the longitudinal axis of the
former is sometimes nearly double that of the latter. Although somewhat variable
in shape, one difference is persistent, namely, in roughness: in some specimens
carefully compared, the papillae which render the stigma rough were in the long-
styled form from twice to thrice as long as in the short-styled. The anthers do
not differ in size in the two forms, which I mention because this is the case
with some heterostyled plants. The most remarkable difference is in the pollen-
grains. I measured with the micrometer many specimens, both dry and wet, taken
from plants growing in different situations, and always found a palpable
difference. The grains distended with water from the short-styled flowers were
about .038 millimetres (10 to 11/7000 of an inch) in diameter, whilst those from
the long-styled were about .0254 millimetres (7/7000 of an inch), which is in
the ratio of 100 to 67. The pollen-grains therefore from the longer stamens of
the short-styled form are plainly larger than those from the shorter stamens of
the long-styled. When examined dry, the smaller grains are seen under a low
power to be more transparent than the larger grains, and apparently in a greater
degree than can be accounted for by their less diameter. There is also a
difference in shape, the grains from the short-styled plants being nearly
spherical, those from the long-styled being oblong with the angles rounded; this
difference disappears when the grains are distended with water. The long-styled