LIFE-HISTORY OF THE HERB ROBERT 115 
experience of inducing pollen grains to start at all, 
but the reader or student should have no great 
difficulty in verifying for himself what I have to say 
about pollination and in adding observations of his 
own. 
As the bright petals suggest, the flower is adapted 
to cross-pollination by insects. The honey is at the 
base of the stamens inside the calyx, and in order to 
reach it an insect must have a tongue about a quarter 
of an inch long. 
I have seen it visited by bees of various sorts 
which have four wings, and by some good-sized flies 
which have only two, but it also secures the services 
of such long-tongued insects as butterflies, among 
others the Garden Whites: they are, however, 
decidedly large for a blossom of this size, and the much 
smaller Blues, which are fortunately so common in 
our country, are more suitable in this respect. 
In my own garden that remarkably pretty butter- 
fly, the Holly Blue, can be seen at work upon it in 
the spring and more rarely in the late summer, but 
these are only a few from a long list of visitors that 
every one who watches can see from time to time 
during the flowering period, although most of us, 
including the author, would be at a loss to give the 
correct name to each. 
Now let us look at the arrangements for cross- 
pollination in the flower itself. 
The ten stamens are in two rows of five each, but 
for the sake of clearness I have only shown five in the 
illustration, three belonging to one row and two to the 
other. 
When the flower opens the stigmas are not mature, 
that is to say, they are not ready to be pollinated : we 
