leaves as well
as flowers possess this ethereal oil, as it is called. Caterpillars do
not like the taste of these oils, and leave these highly-scented plants
alone. It is, however, generally the flowers only that smell; and now
you can guess why they are protected by their fragrance. What is the
most important part of the flower?"

"Its seed," replied Mary.

"Yes; and as the cattle will not eat the flowers, the seed is safe from
them."

"But they eat flowers in hay," said Jack.

"True; but by the time the grass is cut many seeds have ripened and have
dropped out of their husks; and when flowers are dry, as they are in
hay, they lose their particular scent and the oil with it. But the very
perfume which keeps away the enemies of the flower attracts its friends
the insects, whose sense of smell is very keen."

"Why do flowers want insects?" asked Annie.

"Because they want their yellow dust taken from one flower to another,
to ripen their seeds, or to fertilize them, as it is called. The seeds
are far better if they are ripened by the pollen or dust of another
blossom than by the pollen of their own flower. The bees, as you know,
get covered with this dust as they visit one flower after another; some
of it sticks to the bees, but a great deal of it drops off as they rub
against the flowers."

"It's give and take," said Jack. "The flowers give the honey for the
insects to eat, and the insects carry their pollen away for them."

"Yes, that's something like it," said grandmamma. "And now you can see
why flowers which bloom at night need to have a strong odour. There are
some plants which

'Keep their odours to themselves all day'

but towards evening they

'Let the delicious secret out;'

and it is that moths and insects that fly about at night may know
whereabouts the flowers are. The bees are busy in the day-time; but
there are a great many kinds of moths, in fact there are more moths than
there are butterflies, and they only fly about at night, and the honey
of flowers is their sole food. So you see the scent of flowers has a
great use."

"I never thought of that before," said Mary.

"If the flowers which keep open late in the evening have not a very
strong perfume, they are generally white or pale yellow, so as to be
seen easily. There is one of these plants called the evening
primrose--not that it is like a primrose except in colour--at the bottom
of the garden walk."

"Do let us go and see