Parker's first and most obvious move was to interview Penberthy, whom he caught at Harley Street, after surgery hours.
"Now I'm not going to worry you about that certificate, doctor," he began, pleasantly. "We're all liable to make mistakes, and I understand that a death resulting from an over-dose of digitalin would look very like a death from heart-failure."
"It would be a death from heart-failure," corrected the doctor, patiently. Doctors are weary of explaining that heart-failure is not a specific disease, like mumps or housemaid's knee. It is this incompatibility of outlook between the medical and the lay mind which involves counsel and medical witnesses in a fog of misunderstanding and mutual irritation.
"Just so," said Parker. "Now, General Fentiman had got heart disease already, hadn't he? Is digitalin a thing one takes for heart disease?"
"Yes; in certain forms of heart disease, digitalin is a very valuable stimulant."
"Stimulant? I thought it was a depressant."
"It acts as a stimulant at first; in later stages it depresses the heart's action."
"Oh, I see." Parker did not see very well, since, like most people, he had a vague idea that each drug has one simple effect appropriate to it, and is, specifically, a cure for something or the other. "It first speeds up the heart and then slows it down."
"Not exactly. It strengthens the heart's action by retarding the beat, so that the cavities can be more completely emptied and the pressure is relieved. We give it in certain cases of valvular disease—under proper safeguards, of course."
"Were you giving it to General Fentiman?"