"Nothing," said Kate abruptly.
Her face was very pale; there were great black shadows under her eyes.
"We can't think what's the matter with her," said Lucy Rae, one of the botanists. "She was as lively as the best of us until we were coming home."
"I have a headache; it will soon pass off," said Kate. "Don't take any notice of me; I shall soon be quite my ordinary self."
"I want to say something to you, Kate," said Molly suddenly.
Kate looked at her with irritation.
"I am not in the mood to discuss things," she said; "it is quite true that I have a bad headache."
"I won't worry you, dear," said Molly, in her gentlest tones. "Let us walk slowly behind the others."
Kate opened her lips to protest.