Nutrients (see Foods),
Composition of, [135].
Relative quantity needed, [123].
Routes taken by, [175].
Tests for, [136].
Nutriment, storage of, [177]-[180].
Olfactory stimulus, [347].
Opsonins, [34].
Optic thalami, [289].
Orbit, [373].
Organ, defined, [7].
Organism, defined, [19].
Organization, defined, [10].