reasoning power, xi, 237, 243-4, xv, 65, 66, 68; relation to lower animals, 53-68; rudimentary structures in, 56; sense of smell, xi, 77-8; sex determiners in, ix, 338-9; skull capacity, xv, 40-1, 89; skull shapes in, 42-3; stages in development of, 188-204; structure compared with apes, 57-62; struggle for existence in, 25-6, 27; struggle for perfection in, 28-9; survival of fittest in, 27; symmetrical instinct in, 251; tool-using animal, v, 9, 10-11, ix, 67-8, xv, 205; tropical animal, ix, 308-9 (see also Primitive Man) Manatees, jaguars and, xii, 362 Mandan Indians, buffalo dance, xv, 305-6 Mandibles, of insects, xii, 99; of men and apes compared, xv, 94 Mandrills, xii, 379-80 Mangabeys, xii, 379 Manganese, viii, 154; affinity strength, 128; atomic weight and symbol, 383; electrochemical analysis, 295; fusibility, 384; ores, 198, 271; specific gravity, 384; test for, 287, 289 Manganin, resistance, vi, 77, vii, 364 Mangrove Keys, xii, 42 Mangle, Electric, vii, 82-3 Manhattan Elevated Railway, engines and turbines, v, 152-3 Manholes, construction, vii, 30 Mania, hot baths in treatment of, x, 311; of adolescence, 236-7 Maniacs, strength of, xi, 264 Manila Hemp, xiii, 236, 239-40 Manila Paper, source, xiii, 240 Manna, "rains" of, i, 355, 357 Mantids, xii, 107-8 Manual Labor, fatigue from, ix, 81; food requirements in calories, 297 Manufacturing Centers, of future, v, 173 Manufacturing Stage, xv, 187, 203 Manures, as fertilizers, viii, 342-3; as nitrogen source, xiv, 66; waste of, viii, 346 Map-Making, aeronautical, i, 45-8 Maple Tree, antiquity, xiii, 324-5; as forest tree, 86-7; fruit, winged, 57, 58 (fig.); in landscaping, 271-2; petals absent in, 195; seed dispersal, 343; source of sugar, viii, 242-3; in United States, xiii, 368, xiv, 372 (see also Sugar Maple) Maps, discrepancies in, xiv, 10-11; tinting of, iv, 130 Marble, iii, 371; green, 338; metamorphic rock, 380, xiv, 19; reaction with acids, viii, 37 March (of weather elements), i, 205, 376-7 Marchetti, Peter, x, 79 Marconi, distress signal system, vii, 284; wireless messages, 258, 259; wireless work, xvi, 191 Marconi Transmitting System, vii, 263-5 Mare Tenebrosum, i, 55 Mare's Tail Clouds, i, 99, 377 Margarines, vegetable, x, 261, 267 Marine Animals, conditions necessary, iii, 17; large, xii, 297-9, 333-5, 347; mollusks, 57-80; primitive types, 16-24, 26, 32, 128-9; worms, 45, 51, 54 Marine Climate, i, 208, 377 Marine Deposits, iii, 52-5 Marine Meteorology, i, 271-83; founding of, 216 Marine Rivers, xiv, 153 Marine Rocks, xiv, 19; found above sea level, iii, 82-3, 85, 132, 235; in mountains, xiv, 231