228 The Romance of Wild Flowers 
case) bring about self-fertilisation by making several 
consecutive visits to the long-styled flower, though 
probably this does not happen to any great extent, 
for the pollen is very accessible in both forms. Good 
seed is also produced by flowers that never open, as 
in the Violet and Wood Sorrel. The fruit is similar to 
those of Primrose and Pimpernel, but instead of open- 
ing as in either of these, it splits from near the top to 
near the bottom into five valves, but these valves re- 
main connected at either pole, and only allow the seeds 
to sift out between. This plant has the alternative 
name of Featherfoil, which is appropriate enough, for 
its leaves are cut from each side near the midrib into 
a great number of slender lobes, which give a very 
feather-like appearance to the leaves. We have 
previously seen how the submerging of a leaf causes 
it to become either entirely slender, or if fairly 
broad, cut into a number of slender lobes or filaments 
that will offer little opposition to movements of the 
water, and at the same time expose a larger surface 
to catch the small amount of carbonic acid gas that is 
dissolved in the water. 
