Pipestone, red, of the Côteau des Prairies, xxxvii, 393; xxxviii, 138.
Pittsburg, Pennsylvania, account of, _S. P. Hildreth_, xxix, 68, 79.
_Pixii_, rotating magnetic machine, xxiv, 144, 146^f, 196.
Plague in Constantinople, remarks on, xxxiv, 32.
Planes, inclined, in the construction of rail roads, _J. Thomson_, xxiii, 107.
Planera, or Siberian elm, notice of, xx, 377.
Planet, supposed new, beyond Herschel, _Cacciatore_, xxxi, 158. ---- Jupiter and his satellites, _Struve_, xiii, 173. ---- Saturn, xiii, 172; xvii, 162; xxv, 191; xxxvii, 373; xliv, 383. ---- ----, sixth satellite of, xxxiv, 207. ---- Venus, _P. F. de Vico_, xliv, 377, 383. ---- ----, rotation of, xxiv, 204.
Planets moving in a resisting medium, examination of the theory of, _R. W. Haskins_, xxxiii, 1. ----, ibid, remarks on, xvii, 389. ----, sizes of, xxxiii, 17. ----, motion of, represented, xii, 103. ----, comparative oblateness of, xxxi, 222.
Planetary spaces, temperature of, xxxii, 1; xxxiv, 57.
Plants, number of known species, xlix, 172. ---- of New York, number of indigenous, _J. Torrey_, xl, 77. ----, classification of, according to a natural system, _Robert Brown_, i, 435. ----, grand division, into exogens, endogens and acrogens, xxxii, 295. ----, other subdivisions, xxxii, 296, 299. ----, soul or spiritual life of, _C. F. P. von Martius_, xl, 170. ----, ammonia disengaged by growing, x, 190. ----, carbonic acid disengaged by the roots of, xlv, 227. ----, non-decomposition of carbonic acid by, xxxiv, 44. ----, circulation in, _E. Emmons_, xxvi, 99. ----, ---- of sap in, xix, 393. ----, chemistry of, _J. Liebig_, xl, 177. ----, chemical constitution of cellular and woody tissue in, xl, 176. ----, cultivation of, in moss, xiii, 189. ----, crystalline substances from the juice of, xi, 391. ----, crystals in, _Turpin_, xix, 177; xx, 382. ----, crystals of oxalate of lime in, xx, 383; xxi, 372. ----, crystals in the tissues of, _J. W. Bailey_, xlv, 149; xlviii, 17.^f ----, effect of light on the color and movements of, _D. P. Gardner_, xlvi, 1.^f ----, effect of light on the germination of the seeds of, xliv, 352. ----, ---- ---- on the growth of, xliv, 352; xlvi, 397; xlvii, 194. ----, experiments on inorganic elements of, xlvii, 194. ----, effect of climate on geography of, xlvii, 221. ----, effect of frost of the winter of 1837-8 in England, upon, _J. Lindley_, xxxix, 18. ----, ---- of chemical solutions on, xvii, 388. ----, excrementitious matter from, _J. Buel_, xxviii, 267. ----, experiments on garden, _J. T. Plummer_, xl, 197. ----, growth of, in closely glazed cases, xliii, 383. ----, growing under glass, _C. Daubeny_, xxxiv, 11. ----, ---- ibid, _N. B. Ward_, xxxiv, 11. ----, ---- ibid, _J. Yates_, xxxiv, 13. ----, growing on animals, _S. L. Mitchill_, xii, 21. ----, on the development of the external organs of, xxxvii, 187. ----, on the leafing of, xliv, 419. ----, indicators of seasons, ii, 255. ----, phosphorescent, xv, 170. ----, phosphoric acid in, ii, 358. ----, poisoning of, xv, 169. ----, respiration in, xxii, 363. ----, sleep of, xxii, 375. ----, used for cordage, xxi, 27; xxv, 330; xxviii, 371; xli, 200.^f ---- and mosses, iodine in, xlv, 227. ----, fossil, accompanying anthracite coal, ix, 165. ----, ----, at Mariner's Mill, Ohio, xxxi, 28.^f ----, ----, in coal strata of England, iii, 389; xxxiii, 87, 270. ----, ----, of the coal formations, _A. Brongniart_, iv, 266.^f ----, ----, analysis of _Ad. Brongniart's_ work on, vii, 178. ----, see farther under _Botany_ and _Vegetable_.