Newton, Professor, of Yale, on origin of Mars' satellites, 177.

Nucleus, dimensions of, 237; amount of radium in, 238.

Nummulitic beds of Himalaya, 138.

O.

Ocean, amount of rock salt in, 50; cause of black colour of, 55;
estimated mass of sediments in, 48; increase of bulk due to
solvent denudation, 52; its saltness due to denudation, 41.

Old age and death, 82-85; not at variance with progressive
activity, 83.

Organic systems, origin of, 78.

Organic vibrations, 86 _et seq._

Organism and accelerative absorption of energy, 79; and economy,
109-111; and periodic rigour of the environment, 94,95.

Organism and sleep, 95; ultimate explanation of rythmic events
in, 96, 97; law of action of, 68 _et seq._; periodicity of; and
law of progressive activity, 82 _et seq._