Part 35

Sensitive-plants, 59

Sexes of butterflies differently coloured for recognition, 196

Sexual colours, 177 theory of, 192

Sexual selection not a cause of colour, 198 neutralized by natural selection, 210

Sickle-bill humming-bird, 136

Size, correspondence of, in tropical flowers and insects, 236

Sky, colour of not mentioned in old books, 245

Smith, Mr. Worthington, on mimicry in fungi, 223

Smyth, Professor Piazzi, on the Great Pyramid, 298

Snakes, 114

Sobralias, 51

Soil, heat of, 8 influence of temperature on climate, 8

Solenopsis, genus of ants, 84

Sorby, Mr., on composition of chlorophyll, 221

South America, extinct fauna of, 336 geographical changes of, 338 its parallelism with Africa, 339 an area of preservation of ancient types, 339

Spices from equatorial forest-trees, 36

Spiders, 97

Spruce, Dr. Richard, on number of ferns at Tarrapoto, 47 on inconspicuousness of tropical flowers, 61 on use of aromatic secretions of leaves, 278

Stainton, Mr., on insects attacking scented leaves, 277

Stick-insects, 92

St. Helena, indigenous flowers of, 275

St. John, Mr., on large python, 115

Structure of humming-birds, 125

Sugar from palm-trees, 44

Sunda Islands and Japan once joined to Asia, 326

Sun-birds, differences from humming-birds, 154

Sun’s noonday altitude in Java and London compared, 6

Sun’s rays, heating effect of, 7