When the lesions constituting the eruption are of two or more types or characters.

When are lesions said to be aggregated?

When they tend to form groups or closely-crowded patches.

When are lesions disseminated?

When they are irregularly scattered, with no tendency to form groups or patches.

When is a patch of eruption said to be circinate?

When it presents a rounded form, and usually tending to clear in the centre; as, for example, a patch of ringworm.

When is a patch of eruption said to be annular?

When it is ring-shaped, the central portion being clear; as, for example, in erythema annulare.

What meaning is conveyed by the term “iris”?