Sphærococcus coronopifolius, mode of reproduction of, i. 236, 238 Sphærococcus, habitat of the genus, i. 239 Sphærophorei, characters of the, i. 310 Sphæroplea annulina, structure and reproduction of, i. 208, 209 Sphagnei, characters of, i. 331 Sphagnum latifolium, leaves of, i. 330 Sphagnum, or common bog-moss, structure, fructification, and habitat of, i. 332 uses of, in Lapland, i. 334 Spikenard, amount of radiant heat absorbed by the perfume of, i. 44 Spinal cord, structure and functions of the, ii. 8 Spines of plants, structure and formation of, i. 411 Spirogyra, mode of reproduction of, i. 218 Spirulina tenuissima, motions of, i. 213 Splachnei, characters of the tribe, i. 330 Splachnum ampullaceum, structure and habitat of, i. 331 Splachnum vasculosum, structure and colour of, i. 330 Spondylus gædaropus, eyes of the, ii. 235 Sponges, iodine found in, i. 19 Sponges, the Carpenteria, a link between the foraminifera and the, ii. 57 structure and development of, ii. 57 varieties in size, structure, and habits of the marine sponges, ii. 60 propagation of, ii. 60, 61 structure of fresh-water sponges, ii. 61 fossil sponges, ii. 62 Spongilla fluviatilis, structure and development, and propagation of, ii. 61 Spongiocarpeæ, structure and mode of propagation of, i. 237, 238 Spores of Cryptogamia, i. 177, 178 Sporidia, or spore-bearing cells, of Ascomycetes, i. 290 Sporidiiferi, structure and fructification of, i. 260 orders of, i. 260, 261 Sporiferi, structure and fructification of, i. 260 orders of, i. 260 Sporopodium Leprieurii, ascus of, i. 300 Spurgeworts, poisons and food supplied by the, i. 425, 426 Squamariæ, structure and modes of propagation of, i. 237 Squid, structure of the, ii. 245, 246 Squilla Desmarestii, structure of, ii. 198 Squilla mantis, structure of, ii. 198 Stamens of flowering plants, i. 379 Starch, production of, by plants, i. 420 Star-fishes, structure of, ii. 169 Stars, absorption of the heat radiated by the, by the earth’s atmosphere, i. 55 chemical power of the light of the, i. 55 Stars, falling, i. 28 Stars, fixed, constitution and spectra of the, i. 154, 155, 162, 163 spectra of periodic stars, i. 156 Staurastrum, structure and development of various species of, i. 192 Steam-engine, equivalence between the mechanical work and heat of the, as between cause and effect, i. 29 causes of the motive force in the, i. 29 Steel, effect of magnetism on, i. 77 importance of the spectrum analysis in the manufacture of, by Bessemer’s process, i. 137, 138 Stegobolus Berkeleianus, structure and organs of development of, i. 299 Stelleridæ, structure and mode of reproduction of, ii. 169-172, 174 Stems of plants, structure of, i. 384, 405 Stenochlæna, stem of, i. 339 Stephanosphæra pluvialis, structure and development of, i. 187-189 Stickleback, entozoön of the, ii. 145