^{page 230 note *} Benthos (βέν⎸οσ, bottom of the sea) is a term introduced by Haeckel for all those organisms living on or creeping over the bottom of the sea, in contradistinction to Plankton, which, as extended by him, includes all those organisms swimming about in the sea or carried along in ocean currents (Plmiktmi-Studien, Jena, 1890).Google Scholar

^{page 231 note *} Thoulet, Comples Itendus, tome xcviii. p. 1000, 1884.Google Scholar

^{page 231 note †} Sollas, Zool. Chall. Exp., part lxiii. pp. 47 et seq.

^{page 232 note *} Pearcey, Proc. Hoy. Phys. Soc. Edin., vol. viii. p. 400.

^{page 233 note *} Nηρίίησ, son of Nereus (see Haeckel, Plankton-Studien, p. 22, Jena, 1890).Google Scholar

^{page 231 note †} t Haeckel, loc. Cit.

^{page 236 note *} The balance used by us was not very delicate; the results can only be relied on to the third place of decimals.

^{page 236 note †} Exp. (A). To determine this point we added silicic acid in a soluble form to a litre of artificial sea-water (which water was practically free from silicic acid),

^{page 237 note *} Bischoff, Chemical and Physical Geology, vol. i. p. 3. Mr Alexander Johnstone, F.G.S., has proved experimentally that pure water, even when saturated with carbonic acid, has no solvent action on pure tale or steatite, but that sea-water has a slight but distinct effect in this direction equal to 1 part in 200,000. His results are also interesting as showing that silicate of magnesium once formed cannot be conveyed to any extent in a soluble condition by river water to the sea (Proc. Boy. Soc. Edin., vol. xvi. pp. 172–175, 1889).Google Scholar

^{page 239 note *} A solution of silicate of soda was neutralised with carbonic acid, and an amount of this solution equal to 1 grm. of soluble or colloid silicic acid added to 1 litre of sea-water. A comparatively small precipitate resulted, and was found to consist of silicic acid and silicate of magnesia, with traces of lime. The clear liquid filtrate from this precipitate remained for a very long period perfectly clear, and only deposited a slight additional precipitate after standing more than fourteen days. The silicic acid was determined in the filtrate, and it was found that the amount of the precipitate corresponded with the carbonate of magnesia or lime which occurred in the water. Thus if soluble silicic acid in any circumstances be added to sea-water, we should expect only that portion thrown out that would thus combine with the alkaline constituents of the sea-water, the amount of alkaline constituents being always enormously in excess over that in which silicic acid could exist either in surface or bottom water.

^{page 239 note †} Loc. cit., vol. i. pp. 76, 77.

^{page 240 note †} See Murray, and Irvine, , “Coral Reefs and other Carbonate of Lime Formations in Modern Seas,”Proc. Roy. Soc. Edin., vol.xvii. pp.79–109, 1890.Google Scholar

^{page 241 note *} Advantage is taken of this fact in the purification of muddy waters for domestic and manufacturing purposes by adding lime and alumina salts, which induce the separation of suspended matter and its subsidence (see Sidell in Humphreys and Abbot's Report on the Mississippi, Appendix A, No. 2, pp. 495 etseq., 1876; Schultze, PoggAnn., vol. 129, p.366, 1866).Google Scholar

^{page 243 note *} = 27,500 tons per cubic mile of water.

^{page 243 note +} = 14,200 tons per cubic mile of water.

^{page 243 note ‡} =7740 tons per cubic mile of water.

^{page 243 note §} =1300 tons per cubic mile of water.

^{page 244 note *} We are indebted to Captains Thomas S. Knox and George Read, of the Anchor Line, for collecting the waters from the Mediterranean, Indian, and Atlantic Oceans.

^{page 245 note *} Johann Nave, writing of Diatoms, remarks that these Algae abound wherever water collects, from the sea to the smallest puddle on the wayside, and are generally associated with clay or mud. Gerstenbergh's plan for the propagation of Diatoms is instructive. He spreads the mud (containing Diatoms) on a plate or shallow dish, and exposes it to the full light of the sun. Stimulated by its rays, the plants begin to multiply rapidly, and on removal those left in the mud may be stimulated into active production by repeating the same process. By degrees the vitality of the little plant exhausts itself, and it is necessary to revive their vegetative powers. This may be accomplished by creating an artificial spring and winter. You have only to allow the water to evaporate, and the mud to become nearly, but not quite, dry, when, on fresh water being poured over it, vegetation commences anew. In this way gatherings originally poor may be made to yield an abundant supply of Diatomacea.

^{page 247 note *} Sachs' Physiology of Plants, pp. 262, 263.

^{page 247 note †} See Poucliet and Chabry, “L'eau de mer artificielle comme agent tératogénique,” Journ. de l'Anatomie, 1889, pp. 289–307.Google Scholar

^{page 249 note *} In this connection Julien states (“On the Geological Action of Humus Acids,” Proc. Amer. Ass., vol. xxviii. p. 359)—”Considerable evidence now exists that a substance corresponding to humus, simply in its yield of acid solvents of lime, oxides of iron, manganese, &c, enters universally into the constitution of the layer of ooze upon the bottom of the ocean. Its exact composition has never yet been determined; but it may be suspectSB. that it resembles that of glairine, especially in its high content of silica. As it has resulted from the continuous decomposition of the cellulose membranes of the diatomaceae, &c, and of the gelatinous sarcode of the radiolaria, spongise, and foraminifera, which may be there living or deposited by subsidence from the surface, its composition must differ widely from that of the humus of subaerial eremacausis, in its large proportion of water and nitrogen and in its poverty in carbon. It must thus present the most favourable conditions for rapid dissociation.”

^{page 250 note *} The abstraction of silicic acid from silicate of alumina will, of course, necessitate that an equivalent amount of alumina should be accounted for. Doubtless this passes into solution, for in all the sea-waters examined by us, after a most careful filtration, alumina has been found in solution (see also Dittmar's Report, Phys. Chem. Chall. Exp., part i.)