First forms minute, l. 297. See Additional Note [I]. on Spontaneous Vitality.[Back to Canto]
An embryon point, l. 314. The arguments showing that all vegetables and animals arose from such a small beginning, as a living point or living fibre, are detailed in Zoonomia, Sect. XXXIX. 4. 8. on Generation.[Back to Canto]
Brineless tide, l. 315. As the salt of the sea has been gradually accumulating, being washed down into it from the recrements of animal and vegetable bodies, the sea must originally have been as fresh as river water; and as it is not saturated with salt, must become annually saline. The sea-water about our island contains at this time from about one twenty-eighth to one thirtieth part of sea salt, and about one eightieth of magnesian salt; Brownrigg on Salt.[Back to Canto]
Whence coral walls, l. 319. An account of the structure of the earth is given in Botanic Garden, Vol. I. Additional Notes, XVI. XVIII. XIX. XX. XXIII. XXIV.[Back to Canto]
Drunk the headlong waves, l. 322. See Additional Note [III].[Back to Canto]
An insect-myriad moves, l. 327. After islands or continents were raised above the primeval ocean, great numbers of the most simple animals would attempt to seek food at the edges or shores of the new land, and might thence gradually become amphibious; as is now seen in the frog, who changes from an aquatic animal to an amphibious one; and in the gnat, which changes from a natant to a volant state.
At the same time new microscopic animalcules would immediately commence wherever there was warmth and moisture, and some organic matter, that might induce putridity. Those situated on dry land, and immersed in dry air, may gradually acquire new powers to preserve their existence; and by innumerable successive reproductions for some thousands, or perhaps millions of ages, may at length have produced many of the vegetable and animal inhabitants which now people the earth.
As innumerable shell-fish must have existed a long time beneath the ocean, before the calcareous mountains were produced and elevated; it is also probable, that many of the insect tribes, or less complicate animals, existed long before the quadrupeds or more complicate ones, which in some measure accords with the theory of Linneus in respect to the vegetable world; who thinks, that all the plants now extant arose from the conjunction and reproduction of about sixty different vegetables, from which he constitutes his natural orders.
As the blood of animals in the air becomes more oxygenated in their lungs, than that of animals in water by their gills; it becomes of a more scarlet colour, and from its greater stimulus the sensorium seems to produce quicker motions and finer sensations; and as water is a much better vehicle for vibrations or sounds than air, the fish, even when dying in pain, are mute in the atmosphere, though it is probable that in the water they may utter sounds to be heard at a considerable distance. See on this subject, Botanic Garden, Vol. I. Canto IV. l. 176, Note.[Back to Canto]
So Trapa rooted, l. 335. The lower leaves of this plant grow under water, and are divided into minute capillary ramifications; while the upper leaves are broad and round, and have air bladders in their footstalks to support them above the surface of the water. As the aerial leaves of vegetables do the office of lungs, by exposing a large surface of vessels with their contained fluids to the influence of the air; so these aquatic leaves answer a similar purpose like the gills of fish, and perhaps gain from water a similar material. As the material thus necessary to life seems to be more easily acquired from air than from water, the subaquatic leaves of this plant and of sisymbrium, oenanthe, ranunculus aquatilis, water crow-foot, and some others, are cut into fine divisions to increase the surface, whilst those above water are undivided; see Botanic Garden, Vol. II. Canto IV. l. 204. Note.