54 THE NATURE-STUDY OF PLANTS 
is quite true. Letussee, then, how the space is bridged, 
There are many different ways in which it may be 
done, but I propose to indicate only in a general way 
what is carried out in Nature, with an almost incredible 
amount of variety in detail. 
The pollen grains sometimes reach the stigma of 
their own flower by falling upon it, as we can under- 
stand readily if we turn to a Buttercup or the blossom 
of a Lilac; or, again, they may be knocked on to it 
by an insect. 
But they may fall on to the corolla, and they 
often do; two examples will suffice. In the Ragged 
Robin there are plenty of grains to be seen with a lens 
on the petals, and in the last stage of the flower the 
stigmas grow in amongst them, and so self-pollina- 
tion comes about. 
In the Corn Convolvulus we can find grains upon 
the corolla, but here the device is a different one. 
As the blossom withers it closes up again into a 
crumple, and so the inside of the petals, where the 
grains are, is brought into contact with the stigmas. 
Most people know that in the Primrose there are 
two kinds of flower: one with a long style and the 
stamens below the stigma; the other with a short 
style and the stamens above it. In the latter some 
pollen grains may, of course, drop or be knocked on 
to the stigma; but self-pollination is quite possible in 
the other kind too. Instead of withering into a 
crumple like the Corn Convolvulus, when the right 
time comes, the corolla, while still fresh, drops out of 
the calyx whole, and if we look at it we shall see that 
the stamens adhere to it. Now, the style and the 
stigma do not drop off until after the fall of the corolla, 
and so in the long-styled flowers the stamens are 
