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Also known as roundworm, this is a free-living, transparent nematode, about 1 mm in length, that lives in temperate soil environments.

A layer at the back of the eyeball that contains cells sensitive to light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.

The measurement of electrical activity in different parts of the brain and its recording as a visual trace (on paper or on an oscilloscope screen).

A change in the electrical resistance of the skin caused by emotional stress, measurable with a sensitive galvanometer, e.g. in lie-detector tests.

A record or display of a person’s heartbeat produced by electrocardiography.

The part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.

A record of the standing voltage between the front and back of the eye that is correlated with eyeball movement (as in REM sleep) and obtained by electrodes suitably placed on the skin near the eye.

A self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

Any of a class of nitrogenous organic compounds which have large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, etc., and as enzymes and antibodies.

The process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth.