"Who did that for you?"
"My trained nurse. I will let you have the books and chemists' receipts."
"Thank you. Did your nurse make up the dose for General Fentiman?"
"Oh, no; it is a prescription I always keep by me, ready made up. If you'd like to see her, she will show it to you."
"Thanks very much. Now, when General Fentiman came to see you, he had just had an attack. Could that have been caused by digitalin?"
"You mean, had he been poisoned before he came to me? Well, of course, digitalin is rather an uncertain drug."
"How long would a big dose like that take to act?"
"I should expect it to take effect fairly quickly. In the ordinary way it would cause sickness and vertigo. But with a powerful cardiac stimulant like digitalin, the chief danger is that any sudden movement, such as springing suddenly to one's feet from a position of repose, is liable to cause sudden syncope and death. I should say that this was what occurred in General Fentiman's case."
"And that might have happened at any time after the administration of the dose?"
"Just so."