220 The Romance of Wild Flowers 
blocked by the thickened head (stigma) of the long 
style, the other narrowed by the five anthers round 
the margin. These differences have long been known, 
but no one guessed their meaning, or thought they 
had one, until Charles Darwin pointed it out, and 
now it forms one of the most easily verified examples 
of the numerous contrivances existing among our 
wild flowers for effecting cross-fertilisation. 
Wet the small blade of a sharp penknife and with 
it cut through a Primrose flower, from the stalk 
upwards; then you will see at the bottom of the 
corolla-tube an egg-shaped body (ovary) ending in 
the slender style with a thickened head (stigma). 
Around the ovary a small quantity of nectar is 
produced, and only insects with long tongues can 
reach down to it. If the stigma of the flower you 
have cut comes to the top of the tube, look out for 
another in which the anthers are just inside the 
mouth, and make a section of that in the same 
manner. Then take a bristle, or something equally 
slender, and, pretending it is a bee’s tongue, pass it 
down the tube from above. If the flower you first 
experiment with be a long-styled one, the bristle will 
be covered with pollen from the anthers which are 
about half-way down the tube. Then use the same 
bristle with the short-styled flower, and you will find 
that the pollen from the first is now detached by the 
viscid stigma of the second specimen, which is at the 
same height as are the anthers in the first. At the 
same time, pollen from No. 2 is deposited on the 
bristle at a height corresponding with the stigma of 
No.1. There is a difference also in the size of the 
pollen-grains corresponding with the length of the 
