- The Doctor: [the Doctor and Peri are waiting in a prison cell to be executed] I'm sorry I got you in to this Peri.
- Peri: It's alright. It's not your fault. I mean it's as much my fault as it is yours.
- The Doctor: Yes. Should never have followed those tracks. Curiosity's always been my downfall.
- Peri: Doctor, why do you wear a stick of celery in your lapel?
- The Doctor: Does it offend you?
- Peri: No, just curious.
- The Doctor: Safety precaution. I'm allergic to certain gases in the praxis range of the spectrum.
- Peri: Well how does the celery help?
- The Doctor: If the gas is present, the celery turns purple.
- Peri: And then what do you do?
- The Doctor: I eat the celery. If nothing else I'm sure it's good for my teeth.