[Footnote: _The honey'd sap_, l. 352. The aphis punctures with its fine proboscis the sap-vessels of vegetables without any visible wound, and thus drinks the sap-juice, or vegetable chyle, as it ascends. Hence on the twigs of trees they stand with their heads downwards, as I have observed, to acquire this ascending sap-juice with greater facility. The honey-dew on the upper surface of leaves is evacuated by these insects, as they hang on the underside of the leaves above; when they take too much of this saccharine juice during the vernal or midsummer sap-flow of most vegetables; the black powder on leaves is also their excrement at other times. The vegetable world seems to have escaped total destruction from this insect by the number of flies, which in their larva state prey upon them; and by the ichneumon fly, which deposits its eggs in them. Some vegetables put forth stiff bristles with points round their young shoots, as the moss-rose, apparently to prevent the depredation of these insects, so injurious to them by robbing them of their chyle or nourishment.] [Footnote: _The tadpole swims_, l. 359. The progress of a tadpole from a fish to a quadruped by his gradually putting forth his limbs, and at length leaving the water, and breathing the dry air, is a subject of great curiosity, as it resembles so much the incipient state of all other quadrupeds, and men, who are aquatic animals in the uterus, and become aerial ones at their birth.] "So human progenies, if unrestrain'd, By climate friended, and by food sustain'd, 370 O'er seas and soils, prolific hordes! would spread Erelong, and deluge their terraqueous bed; But war, and pestilence, disease, and dearth, Sweep the superfluous myriads from the earth. Thus while new forms reviving tribes acquire Each passing moment, as the old expire; Like insects swarming in the noontide bower, Rise into being, and exist an hour; The births and deaths contend with equal strife, And every pore of Nature teems with Life; 380 Which buds or breathes from Indus to the Poles, And Earth's vast surface kindles, as it rolls!