SUSAN: It's too far for you, Grandfather.

DOCTOR: Well, if it is, I shall have to give up, and I'm not going to give up before I've tried. And remember, you must think of the other two. They must be constantly reminding themselves they're only one inch high. There's only the two of us to help them.

SUSAN: All right. But you let me go first.

DOCTOR: Yes, yes, yes, go on.

(she comes face to face with a giant insect)

SUSAN: Ian! Ian! It is dead, isn’t it?

IAN: Yes. It’s dead, all right. Stiff as a poker. What a fantastic size.

SUSAN: Yes.

IAN: It’s a giant ant.