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].

Osmosis, [72].
At the cells, [72].
To illustrate, [75].