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Show r 1s6 1 Crufl:s the green mo:lfes, and the tangled wood, And fparkling plunges to its parent flood." -0 'er the wann wave a fmiling youth pre fides, Attunes its murmurs, its meanders guides, (The blootning Fucus) in her fparry coves To amorous Echo fings his Jecret loves, Bathes his fair forehead in the mifl:y fiream, And with fweet breath perfumes the rifing fl:eam. -So, edt, an Angel o'er Bethefda' s fprings, Each morn defcending, :ihook his dewy wings 195 200 Fucus. l. I95· Clandefiine marriage. A fpecies of Fucus, or of Conferva, foon appears in all bafons which contain water. Dr. PridHey found that great quantities of pure dephlogifl:icated air were given up in water at the points of this vegetable, particularly in the funlhine, and that hence it contributed to preferve the water in refervoirs from becoming putrid. The minute divifions of the leaves of fubaquatic plants as mentioned in the note on Trapa, and of the gills of filh, feem to ferve another purpofe befides that of increafing their furface, which has not, I believe, been attended to, and that is to facilitate the feparation of the air, which is mechanically mixed or chemically ditTolvcd in water by their points or edges ; this appears on immerfing a d:·y hairy leaf in water frefh from a pump; innumerable globules like quicklilver appear on almofl: every point; for the extremities of thefc points attract the particles of water lefs forcibly than thofe particles attract each other; hence the contained air, whofe elafl:icity was but jufl: balanced by the attraCl.ive power of the furrounding particles of water to each other, finds at the point of each fibre a place where the refifl:ance to its expanfion is lefs; and in confequcnce it there expands, and becomes a bubble of air. It is eafy to forefee that the rays of the funlhine, by being refraCl.ed and in part reflected by the two furfaces of thefe minute air-bubbles, mufl: impart to them much more heat than to the tranfparent water; and thus facilitate their afcent by further expanding them; that the points of vegetables attraCt the particles of water lcfs than they attract each other, is fcen by the fpherical form of dew-drops on the points of grafs. See note on V egctable Refpiration in Part I. r 157 1 And as his bright tran£lucent form He laves, Salubrious powers enrich the troubled waves. Amphibious Nymph, from Nile's prolific bed Emerging TRAP A lifts her pearly head; 7'rapa. 1. 2o4. Four males, one female. 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 footflalks to fupport them above the furface of the water. As the aerial leaves of vegetables do the office of lungs, by expofing a large furface of vetTels with their contained fluids to the influence of the air; fo thcfe aquatic leaves anfwer a fimilar pmpofe like the gills of fi{h; and perhaps gain from water or give it to a fimilar material. As the material thus necetTary to life feems to abound more in air than in water, the fubaquatic leaves of this plant, and of fifymbrium, oenanthe, ranunculus aquatilis, water crowfoot, and fome others, are cut into fine divifions to increafe the furface; whilfl: thofe above water are undivided. So the plants on high mountains have their upper leaves more divided, as pimpinella, petrofelinum, and others, becaufe here the air is thinner, and thence a larger furface of contact: is required. The fiream of water alfo pa!Tes but once along the gills of filh, as it is fooner deprived of its virtue; whereas the air is both received and ejected by the action of the lungs of land-animals. The whale feems to be an exception to the above, as he receives water and fp outs it out again from an organ, which I fuppofe to be a refpiratory one. As fpring-water is nearly of the fame degree of heat in all climates, the aquatic plants, which grow in rills or fountains, are found equally in the torrid, temperate, and frigid zones, as water-crefs, watcr-parfnip, ranunculus, and many others. In warmer climates the watery grounds are ufefully cultivated, as with rice; and the roots of fome aquatic plants are faid to have fupplied food, as the ancient Lotus in Egypt, which fome have fuppofed to be the Nymphrea.-In Siberia the roots of the Butomus, or flowering rufh, are eaten, which is well worth further enquiry, as they grow fpontan eoufly in our ditches and rivers, which at prefent produce no efculent vegetables; and might thence become an article of ufeful cultivation. Herodotus affirms that the Egyptian Lotus grows in the Nile, and refembles a Lily. That the natives dry it in the fun, and take the pulp out of it, which grows like the head of a poppy, and bake it for bread. Enterpe. Many grit-il:ones and coals, which I have feen, feem to bear an impreffion of the roots of the N ymphrea, which are often three or four inches thick, efpecially the white-flowered one. |