Part 14

Glass. A substance made by mixing silicates and including some alkali silicate. Not every sort of glass is transparent.

Glomerate. Gathered in a compact group.

Glottis. The opening at the upper end of the windpipe.

Glucinum or beryllium. A metallic element. Symbol: Gl or Be.

Glucose. One of a group of sugars, including grape sugar.

Gneiss. A sort of highly crystalline rock arranged in layers, as of quartz and mica.

Gold. A metallic element. Symbol: Au.

Gram. The unit of weight in the metric system. About the weight of a cubic centimeter of water at its greatest density.

Graph. A symbolical diagram, as in mathematics of chemistry.

Gravity or gravitation. The attraction existing between bodies. If the earth draws a falling apple, it is said that the apple also draws the earth to it.

Gregarious. Living in or pertaining to flocks, groups, or communities. Social.

Gymnosperm. A plant whose seeds are not enclosed in seed-vessels.

Habit. An action pattern; specifically, one that has been acquired. In biology, a mode of growth.

Hallucination. The perception of something which is not actually present.

Hardness. The presence of certain salts in water.

Heat. Energy which can be transmitted by conduction or radiation, and which is expressed in molecular motion.

Helium. A gaseous element. Symbol: He.

Henry. The unit of inductance. The inductance in a circuit in which the induced electromotive force is one volt when the inducing current varies at the rate of one ampere per second.

Herb. A plant whose stem is not woody or persistent.

Hermaphrodite. An organism possessing male and female characteristics or organs.

Herpetology. The study of reptiles.

Hexapoda. The order of insects.

Hilum. The point where the seed is attached to the seed-vessel.

Hinterland. The district behind a coast.

Histology. The study of organic tissues, usually with the aid of a microscope.

History. The study of the past. It deals with human institutions rather than with the animal, vegetable, or mineral kingdom. History is concerned first of all with concrete data, specific cases, and then with explaining them in the light of general laws. There have been some ingenious, but not altogether successful, attempts to make history into a science.

Holmium. A metallic element. Symbol: Ho.

Homo-. In compounds: same, similar.