IV ON PLANT LIFE 123 
the Scotch Fir. When, on the contrary, the 
pollen is carried by insects, the quantity nec- 
essary is greatly reduced. Still it has been 
calculated that. a Peony flower produces be- 
tween 3,000,000 and 4,000,000 pollen grains ; 
in the Dandelion, which is more specialised, 
the number is reduced to about 250,000 ; 
while in such a flower as the Dead-nettle it is 
still smaller. 
The honey attracts the insects; while the 
scent and colour help them to find the flowers, 
the scent being especially useful at night, 
which is perhaps the reason why evening 
flowers are so sweet. 
It is to insects, then, that flowers owe 
their beauty, scent, and sweetness. Just as 
gardeners, by continual selection, have added 
so much to the beauty of our gardens, so to 
the unconscious action of insects is due the 
beauty, scent, and sweetness of the flowers of 
our woods and fields. 
Let us now apply these views to a few 
common flowers. ‘Take, for instance, the 
White Dead-nettle. 
The corolla of this beautiful and familiar 
