Mammoth Cave, general impressions of, 241, 242, 248; relics of 1812, 242; the clock, 243; timidity of visitors, 243, 244; a dark city, 244; as a sanitarium, 244, 245; the Star Chamber, 245, 246; musical rocks, 246, 247; water in, 247, 248; Goring Dome, 248; the entrance, 248, 249; a river of cool air, 249, 250. Maple, red, 17. Maple, sugar, keys of, 152; starting of the sap, 159; a good sap day, 160, 161. March, a typical day of, 161; tokens of, 219, 220. Marigold, marsh, 19. Marsh-mallow (_Althæa officinalis_), 12. Martin, Mrs., her _Home Life on an Ostrich Farm_, 86. Martin, purple (_Progne subis_), eggs of, 65. Meadow-beauty, _or_ rhexia, 10. Meadowlark (_Sturnella magna_), 236; notes of, 165, 167. Medeola. _See_ Indian cucumber root. Melilotus. _See_ Clover, sweet. Milkweed, marsh, 13. Mimicry, 308, 309. Mimulus, purple, _or_ monkey-flower, 29. Mink (_Putorius vison_), 103, 104; tracks of, 126, 127, 309. Mockingbird (_Mimus polyglottos_), 239, 302; song of, 308. Monarda, _or_ bee-balm, 11. Monkey-flower. _See_ Mimulus. Moose (_Alce alces_), pursuit of a, 280, 281. Mountain-ash, 42. Mountain-climbing, in the Catskills, 33-60. Mountains, their meaning to Oriental minds, 44, 45. Mt. Graham, 43. Mount Sterling, 223. Mt. Wittenberg, 35, 38, 56, 57. Mouse, meadow, 256; crossing a lake, 309-311. Mouse, white-footed, a mother with her young, 311. Mouse-ear, 21-23. Muskrat (_Fiber zibethicus_), 103, 104; in a doorway, 177, 178, 303. Nature, the language of, 118; various forms of the love of, 203, 204; the real lover of, 205, 206; the passion for Nature not a mere curiosity about her, 207, 208; the creative touch of the imagination needed in descriptions of, 213, 215; fresh impressions of, 215-220; many dramas played at once on her stage, 268; all things to all men, 269, 270; the gradations in, 307-309. Neversink, the, 34. Newt, water, 162. Night, Jefferies on, 213; Whitman on, 213, 214; in Senancour's _Obermann_, 214, 215. Nightingale, song of, 308. Oaks, English, 212. _Obermann_, by Étienne Pivert de Senancour, quotation from, 214, 215.