Pertussis.—Whooping-cough.
Proteid.—One of the complex nitrogenous substances constituting the essential parts of animal and vegetable tissues.
Protozoön (pl. protozoa).—An animal organism composed of a single cell.
Pus.—The fluid product of inflammation; matter.
Putrefaction.—Decomposition of nitrogenous organic matter brought about by micro-organisms and accompanied by a foul odor.
R
Resistance.—[See Immunity.]
Respiratory Tract.—The air passages, including the nose, mouth, larynx, trachea, bronchial tubes, and lungs.
S
Saprophyte.—A vegetable organism that lives on decaying organic matter.