148 
POPULAR SCIENCE REYEEW. 
Spurred. The pollen grains are small, and require the micro- 
scope to determine their form, which is elongated, with convex 
sides and truncated extremities (fig. 26). 
The style is club-shaped, hooked at the apex with the stigma 
on the under surface (fig. 27). As it stands, surrounded by the 
stamens, the hooked apex alone is visible (fig. 25). The ovary, 
it will be observed, from the longitudinal section of the flower 
(fig. 21), is superior and somewhat conical, bearing the ovules 
from each side. If a transverse section of the ovary is made, it 
will appear slightly triangular in outline, with the walls thick- 
ened a little into three equidistant placentae, on which the ovules 
are produced (fig. 28). The ovary is undivided, and therefore 
one -celled, with three parietal placentae, or placentae of the 
wall of the cell. Comparison of the ovary of the primrose with 
the ovary of the violet will show that they both agree in the 
ovary being superior, and in being one-celled ; but they differ in 
the ovules of the primrose being borne from the centre, and in 
the violet from the walls of the ovary. Moreover a comparison 
of other parts of the flower will exhibit differences in the 
calyx, in the corolla, in the stamens, in the style, in the stigma, 
and in the pollen granules. Prominent above all will be the 
distinction between the monosepalous calyx of the one and the 
polysepalous calyx of the other, and between the monopeta- 
lous regular corolla of the one and the polysepalous irregular 
corolla of the other. 
The snowdrop {GalantJius nivalis) will serve as another 
example of flower dissecting ; and in this instance we have 
also a common and familiar object upon which to perform our 
operations. The first superficial observation will be sufiicient for 
us to note the entire absence of a green calyx, which is present 
in so many flowers. Instead of a calyx, we appear to have white 
petals. Let us strip them off carefully, one by one. There are 
three white floral leaves standing in a circle around the circum- 
ference of the flower ; but beneath these are others, and smaller 
ones, notched at the apex, and ornamented near the notch with 
a crescent-shaped green spot (fig. 29). These may also be re- 
moved and placed beside the others, and are again three. So 
that we have three outer petals, which correspond to a calyx, 
only that they are white, and three inner and smaller ones, 
corresponding to a corolla. If the scars left by the removal of 
these flower-leaves are examined closely, the three inner are 
seen to be alternate with the three outer. Or, if a flower is cut 
transversely a little beyond the green ovary, we shall observe 
much such an arrangement as is indicated diagrarnmatically in 
fig. 35. The six floral leaves constitute what is termed a perianth ; 
for although there is no green calyx, the outer circle manifestly 
orresponds therewith. The difference in form, size, and colouring 
