Part 21

Phylo-. In compounds, tribe, race. As, phylogeny: racial development, the natural history of a type.

Phylum. One of the largest divisions of animals or plants.

Physics. The science of matter and energy, not including fields which are considered chemical or biological.

Pistil. The female organ of a flower, including style, stigma, and ovary.

Planet. One of the bodies which revolve about the sun, including the earth but not comets or meteors.

Plant. A living organism which is not an animal. One which does not have sensation or voluntary motion. (This definition must be revised in the light of recent investigations.) Specifically, one of the smaller plants, excluding trees and shrubs.

Platinum. A metallic element. Symbol: Pt.

Pleistocene. Of the geological epoch before the Recent, in the Quaternary period of the Cenozoic era.

Pole. One of the two points in the celestial sphere about which the stars seem to revolve. One of the extremities of the axis of the earth. One of the points on a magnet where magnetic force is manifested. The anode or the cathode of a cell. The extremity of an axis of a spherical or oval cell or organ.

Politics. The science of government. Popularly, the art of exploiting democratic citizens, as practiced by office-holders and those who control them.

Pollen. The substance discharged from a flower, fertilizing or male grains.

Pollination. The carrying of pollen to the pistils.

Polonium. A substance found in pitchblende, perhaps an element.

Poly-. In compounds, many-. For example, polyadelphous: having the stamens united in three or more bundles. Polyandrous: having at one time more than one husband. Polygynous: having at one time more than one wife.

Postglacial. Belonging to a later period than that of the glaciers. Recent.

Potassium. A metallic element. Symbol: K.

Potential energy. Energy which is latent, not employed or in motion. Energy which a body has because of its position.

Poundal. The force which can act upon a pound mass for a second to give it a velocity of one foot per second, or which will give a mass of one pound an acceleration of one foot per second each second.

Practice. What is true in theory works out in practice, all due allowances for the influence of other theoretic laws having been made.

Praseodymium. A metallic element which occurs in rare minerals. Symbol: Pr.

Pre-Cambrian. Relating to the geological eras before the Cambrian period.

Precipitate. To change into liquid form. To cause a substance to be deposited in solid form from a solution. To make a dissolved substance insoluble. That which has been precipitated.

Prehensile. Used for grasping, suitable for grasping.

Pressure. The amount of exertion of force, expressed by the weight upon a unit area.

Primate. A member of the highest order (Primates) of mammals, including man and the monkeys.

Property. That which belongs to a whole class but is not used to distinguish it from others. Characteristic. A legal right to wealth.

Protean. Variable, readily changing form.

Proteid. Protein, or member of a special class of proteins.