"How can you be certain?"

"I have my work, and it takes up so much of my time that it wouldn't be fair to any woman to marry her."

"She mightn't let it take up so much of your time."

"Then it wouldn't be fair to my work."

"I see.... You feel it as a sort of priesthood, with a vow of celibacy attached?"

He thought for a moment and then answered: "I don't know—maybe I do feel that. I don't very often think about it."

But the oddest thing was yet to come. About five o'clock the tousled head of the laboratory-boy intruded itself round the corner of the door. He was a rough-mannered youngster, and, ignoring the presence of visitors, he boldly asked if he could go home. "I've cleaned all the cages," he said, "and I've fed your mice and Mr. Hensler's cats."

The permission was given him and he withdrew. But I could see instantly that the matter would not be allowed to end there. As soon as he had gone Mrs. Severn exclaimed: "I say, what's all this about cats and mice and cages? Do you keep a menagerie?"

Terrington smiled. "No—only what you said—cats and mice and cages. Oh, and a few rats also, I believe."

"But what do you have them for?"