_Carboniferous._ Pertaining to a Paleozoic (geological) period following the Devonian. _Carburetor_ or _carburettor_. A device which mixes air with petroleum vapor, or one which puts illuminants into water gas. _Cardio--._ Heart--, in many combinations. _Carina._ A ridge-shaped structure. _Carnivora._ The flesh-eating mammals. _Carpel._ An organ which is part of the pistil. _Catabolism._ Destructive metabolism. _Catalysis._ The effect produced by a substance (called the catalyst, the catalytic agent, or the catalyzer) which aids a chemical change in other bodies, undergoing no change of its own. _Cathode rays._ Rays discharged from the cathode (negative pole) of a vacuum tube. They are considered streams of electrons, which may be projected at a velocity of 100,000 miles per second. _Caudal._ Relating to the tail. _Cause._ That which brings about something else (an effect). Professor Adam Leroy Jones says: “It has been objected that we can never observe one thing producing another; that we can at most observe that one thing is followed by another, and perhaps find reason for believing that it will always have such connection; and that to say that A _produces_ B, is to raise a metaphysical question with which science and everyday thinking are not concerned.... Is it sufficient to say that cause means simply invariable connection? No, for the succession of day and night is an invariable succession. The notion of cause implies that the relation of cause and effect not only _is_ invariable, but also that it must _be_ so; that there is an _unconditional_ or necessary connection between the two; that if the first does not happen, the second cannot.... A causal law is a statement, in general terms, of a causal connection.” _Cell._ A battery unit, a device for changing chemical energy into electricity. The structural unit of which living beings are composed. An enclosed cavity in an organism or a mineral. A covering which protects the eggs or the young of certain animals. _Celsius._ Centigrade (thermometer). _Cenogetic._ Pertaining to individual development which does not repeat the development of the group of which the individual is a member. _Cenozoic._ Relating to the geological age of the mammals. It is still in existence. _Center of gravity._ The point in a body where its entire weight may be assumed to be concentrated. _Centigrade._ A thermometer, or the scale on which it is based, with the boiling point of water at 100 and the freezing point at zero, under standard conditions of pressure. Abbreviation: C. Such a scale is far more useful to scientists than that of Fahrenheit. _Centimeter._ One hundredth of a meter. _Centrifugal._ Flying or tending to fly away from the center. _Centripetal._ Tending to move toward the center. _Centrosome._ A minute body found in the cytoplasm or the nucleus of some (biological) cells. _Centrum._ The center of an earthquake. _Cephalic._ Relating to the head.