PROTEAN. — Exceedingly variable.

PROTOZOA. — The lowest great division of the animal kingdom. These animals are composed of a gelatinous material, and show scarcely any trace of distinct organs. The Infusoria, Foraminifera, and sponges, with some other forms, belong to this division.

PUPA (pl. PUPAE). — The second stage in the development of an insect, from which it emerges in the perfect (winged) reproductive form. In most insects the PUPAL STAGE is passed in perfect repose. The CHRYSALIS is the pupal state of butterflies.

RADICLE. — The minute root of an embryo plant.

RAMUS. — One half of the lower jaw in the Mammalia. The portion which rises to articulate with the skull is called the ASCENDING RAMUS.