Charles Darwin: The Origin of Species by means of Natural Selection

GLOSSARY 1. GLOSSARY OF THE PRINCIPAL SCIENTIFIC TERMS USED IN THE PRESENT VOLUME. (continued)

POLYZOARY.--The common structure formed by the cells of the Polyzoa, such as the well-known seamats.

PREHENSILE.--Capable of grasping.

PREPOTENT.--Having a superiority of power.

PRIMARIES.--The feathers forming the tip of the wing of a bird, and inserted upon that part which represents the hand of man.

PROCESSES.--Projecting portions of bones, usually for the attachment of muscles, ligaments, etc.

PROPOLIS.--A resinous material collected by the hivebees from the opening buds of various trees.

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.

RANGE.--The extent of country over which a plant or animal is naturally spread. RANGE IN TIME expresses the distribution of a species or group through the fossiliferous beds of the earth's crust.

RETINA.--The delicate inner coat of the eye, formed by nervous filaments spreading from the optic nerve, and serving for the perception of the impressions produced by light.

RETROGRESSION.--Backward development. When an animal, as it approaches maturity, becomes less perfectly organised than might be expected from its early stages and known relationships, it is said to undergo a RETROGRADE DEVELOPMENT or METAMORPHOSIS.