Part 20

Osmium. A metallic element. Symbol: Os.

Ovary. The part of the pistil which contains rudimentary seeds. One of the two reproductive organs in which eggs are produced.

Overtone. A tone produced by secondary vibrations, as of segments of a piano wire.

Ovum. An egg or female germ. Plural: ova.

Oxidize. Combine with oxygen.

Oxygen. An important gaseous element. Symbol: O. About one-fifth of the air is oxygen.

Paleo-. In many combinations, old, ancient. Also: palæo-, palaeo-.

Paleozoic. Of the oldest geological periods. More usually, of the era between the Mesozoic and the Pre-cambrian. The words designating geological eras have been used differently by various scientists.

Paleontology. The science dealing with life in former geological periods, with species now extinct but made manifest by fossil remains.

Palladium. A metallic element of the platinum group. Symbol: Pd.

Parallax. The apparent displacement of an object caused by the actual change in the position of the observer, or by the assumption of two different points of observation. The parallax is expressed in degrees of an angle.

Paralogy. Mental illness.

Parasite. A plant or animal that derives nourishment or shelter from another upon which, with which, or within which it lives.

Parthenogenesis. Reproduction without the union of male and female.

Pascal’s Law. The law formulated by Pascal which is fundamental for the mechanics of fluids: A fluid under pressure exerts equal force upon equal areas of surface.

Pelagian or pelagic. Relating to the open sea. Pelagic organisms are those which do not approach the shore.

Penology. The study of punishment for crime. If this science were studied scientifically, perhaps it would cease to exist.

Perennial. Lasting for several years; specifically, lasting for more than two years.

Phagocyte. A leucocyte which consumes disease-producing organisms.

Phase. The aspect of the moon or of a planet depending on the amount of illumination. Position of variation with regard to a real or assumed starting-point. An individual chemical in a mixture.

Phenomenon. Probably more familiar in the plural: phenomena. Something which is perceived by the senses. An event of scientific interest.

Philology. The science of language. The philologists have been inclined recently to extend their science, so that it deals with meaning, with folklore or traditional beliefs, and with various other subjects which are more or less closely related to language.

Philosophy. Literally: the love of wisdom. Former: the sum of knowledge, a complete system of knowledge, sometimes with emphasis upon its use in regulating human conduct. Philosophy is now primarily ethical. Durant insists that the growth of the various sciences makes it all the more necessary to be concerned with philosophy, which directs the proper use of knowledge. Religion, incidentally, is concerned chiefly with the field indicated for philosophy, not with the ground covered by the various sciences.

Phonology. The study of sounds in speech.

Phosphorus. A non-metallic element. Symbol: P.

Photics or photology. The science of light.

Photo-. In compounds, light or photographic.

Phyllo-. In compounds, leaf. For instance, Phyllopoda: an order of crustaceans with feet resembling leaves.