Ozone, i. 7 effect of the combination of ozone and oxygen in the absorption of radiant heat, i. 43 Prof. Tyndall’s conjecture as to the production of ozone, i. 44 its affinity for iodine, i. 96 its possible effect on the solar spectrum, i. 132 production of, i. 17 P Padina Pavonia, or Peacock’s tail laver, structure of, i. 247 Pagurus, or hermit crab, structure and mode of reproduction of, ii. 197 Palm, stem or axis of a, i. 384 growth and reproduction of palms, i. 384, 385 Palmoglœa macrococca, structure and development of, i. 182 Palmyra palm, growth of the stem of, i. 385 Pandanus or screw pine, roots and habitat of, i. 387 Papillaris, siliceous skeleton of, ii. 60 Paraffin, i. 105 crystals of, how produced, i. 127 Paraffin oil and candles, i. 119, 127 Paramœcium caudatum, cilia and mouth of, ii. 68, 69 immense propagation of, ii. 74 Parkeriaceæ, or Ceratopteridineæ, structure and habitat of, i. 363 Parmelia saxatilis, structure and habitat of, i. 305 Parmeliacei, structure of the, i. 302 characters of the group, i. 304 Parmelia parcolerina, yellow dye obtained from the, i. 124 Parmelia parietina, dye obtained from, i. 303 Passalus cornutus, parasitic fungus in the stomach of, i. 274 Patchouli, amount of radiant heat absorbed by the perfume of, i. 44 Patellidæ, or limpets, structure, food, and habitat of, ii. 238, 239 Paulia perforata, organs of reproduction of, i. 301 Pea mildew, fungus producing the, i. 295 Peach, cause of blistered leaves of the, i. 291 Pear, cause of blistered leaves of the, i. 291 Pearl oyster, nacreous lining of shell of, ii. 234 Pease, caseine obtained from, i. 125 Peat, and peat mosses, i. 333 Pecten, or scallop, eyes of the, ii. 235 Pediastrum, structure and development of, i. 194 Pedicellaria globosa, structure of, ii. 180 Pelagia, structure and mode of reproduction of, ii. 97 Peltigeri, characters of the group, i. 305 Peneroplis, structure of, ii. 31, 32 Penicillia mould, structure of the, i. 285 Penicillium armeniacum, spores of, i. 285, 286 Penicillium candidum, production of, i. 287 Penicillium glaucum, structure and habitat of, i. 286, 287 its polymorphous character, i. 287 in the yeast of beer, i. 288 its production of acetic fermentation, i. 288 Pennatula phosphorea, structure and habitat of, ii. 128 modes of reproduction of, ii. 129 Pennatulidæ, or sea-pens, structure, habitat, and mode of reproduction of, ii. 128, 129 Pentacrinites, structure of, ii. 175 Pentacrinus caput-Medusæ, structure and habitat of, ii. 175 Pentacrinus Europæus, structure of, and change to a comatula, ii. 176 Peppermint, absorption of radiant heat by the perfume of, i. 44 Peranemeæ, or Woodsieæ, characters of the group, i. 350