"He went to his dentist a good deal. But what on earth--"

Antony laughed a third time.

"What luck!" he chuckled. "But how do you know?"

"We go to the same man; Mark recommended him to me. Cartwright, in Wimpole Street."

"Cartwright in Wimpole Street," repeated Antony thoughtfully. "Yes, I can remember that. Cartwright in Wimpole Street. Did Cayley go to him too, by any chance?"

"I expect so. Oh, yes, I know he did. But what on earth--"

"What was Mark's general health like? Did he see a doctor much?"

"Hardly at all, I should think. He did a lot of early morning exercises which were supposed to make him bright and cheerful at breakfast. They didn't do that, but they seemed to keep him pretty fit. Tony, I wish you'd--"

Antony held up a hand and hushed him into silence.

"One last question," he said. "Was Mark fond of swimming?"

"No, he hated it. I don't believe he could swim. Tony, are you mad, or am I? Or is this a new game?"

Antony squeezed his arm.

"Dear old Bill," he said. "It's a game. What a game! And the answer is Cartwright in Wimpole Street."