114 THE NATURE-STUDY OF PLANTS 
matter of fact, in some other species of Geranium, as, 
for example, the Meadow Cranesbill, they are often 
stained with blue or mauve, which is not by any means 
a common colour for pollen grains. 
Now when one of the grains gets upon the stigma 
it sends out a tube which grows down into the ovary 
below vid the interior of the style, and fertilizes one 

Fic. 45.—Herb Robert. Pollen grains and tube. 
A x 400. B xX 360. 
p, the tube. 
of the small seedlets right at the bottom of the flower, 
and it is through one of the three excrescences that the 
pollen tube starts its growth. How it reaches the 
stigma, or, in other words, how pollination is effected, 
is another matter, and we will give our attention to 
it at once. 
What I have written about the protrusion and 
growth of the pollen tube is not very easily verified 
by direct observation until one has had some personal 
