I shall hereafter have occasion to show that the exotic Lobelia fulgens is never visited in my garden by insects, and consequently, from its peculiar structure, never sets a seed.

Nearly all our orchidaceous plants absolutely require the visits of insects to remove their pollen-masses and thus to fertilise them.

I find from experiments that humble-bees are almost indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower.