which can convey the fertilising dust to the flower for which it is designed. And according to Mr. Darwin _all_ plants are practically diœcious, for he states that the pollen, to have a fertilising effect, must be brought to the pistils of one flower from the stamens of one on another root. Whether this be considered established or not, there remains the fact of the existence of diœcious plants as explaining the admirable design of the provision that a bee in the course of one flight shall gather pollen solely from _one species_. As far as honey-gathering is concerned the bee is not governed by this rule; but for this other important function it becomes absolutely essential that the right pollen, and that only, should be conveyed to the right flower. The careful observer may note how the dust on the bodies of bees varies from yellow to red and brown according to the kind of flowers from which it has been gathered, and the "socks," as the Germans call them, on the two hind legs will be found always of the same colour. To no scientific man are we probably more indebted for observations and deductions upon this branch than to Sir John Lubbock. Whilst this edition was in course of preparation it was the writer's privilege to listen to a lecture upon "Relations of Plants and Insects" delivered by this able investigator before the Society of Arts; and the lecture has since been published as a paper in the _Fortnightly Review_ of April 1877. In the course of his remarks Sir John cited many interesting particulars of the ways in which flowers are protected from the incursions of ants, whose visits would be harmful, both from their rifling the stores from the bees, by whom alone they are likely to be fertilised, and from the liability of the latter to desert any species in which their tender probosces were in danger of being seized by ants--it being the nature of an ant to grapple any pointed thing directed towards her. Kerner was referred to as having observed some of the modes by which such results are obviated. In some cases there are _chevaux de frise_ around the flower, in the form of hairs pointing downwards, or other barriers which the ant cannot penetrate or surmount: notably in the corn bluebottle, which is smooth all over except just beneath the flower, and in the thicket heads of some thistles. In others there are glutinous parts which the ant cannot traverse, as was noticed in the _Polygonum amphibium_, which, when it grows on land, has sticky glands at the extremities of certain hairs, while when in the water, where it is safe already, it is perfectly smooth. Again, there are pendulous flowers, like the snowdrop, which are so slippery on the surface that an ant would immediately slide off, as was humorously illustrated by a sketch prepared with several others by the lecturer's daughter. Facts were also stated showing how the pollen is sometimes preserved by the closing of certain flowers