“Yes. I see. I will tell you. Many years ago I gave an overdose of morphia and the patient died as the result of my carelessness. I—I have never been able to bring myself to give an injection since. Psychologically my behaviour has been weak and unsound. I should have overcome this repulsion, but I have been unable to do so. For some time I even lost my nerve as an anæsthetist. Then I was called in for an urgent case with heart disease and the operation was successful.” He showed Alleyn his stethoscope and told him its history. “This instrument represents an interesting experiment in psychology. I began to mark on it all my successful cases of heart disease. It helped enormously, but I have never been able to face an injection. Perhaps some day I may. Sir John is aware of this—peculiarity. I told him of it the first time I gave an anæsthetic for him. It was some time ago in a private house. He very thoughtfully remembered. I believe that in any case he prefers to give the hyoscine injection himself.”

He turned very white as he made this unhappy confession, and it was curious to see how, in spite of his obvious distress, he did not lose his trick of formal phraseology.

“Thank you so much, Dr. Roberts,” said Alleyn gently. “We need not trouble any more about that. Now, you say you were worried almost from the start about Sir Derek’s condition. Would you describe this condition as consistent with hyoscine poisoning?”

“Ever since Thoms rang up I have been considering that point. Yes, I think I should. In the light of the autopsy, of course, one is tempted to correlate the two without further consideration.”

“Did you notice any definite change in the patient’s condition, or did the same symptoms simply get more and more acute, if that’s the right way of putting it?”

“The pulse was remarkably slow when I first examined him in the anæsthetising-room. The condition grew steadily more disquieting throughout the operation.”

“But, to stress my point, there was no decided change at any time, only a more or less gradual progression.”

“Yes. There was perhaps a rather marked increase in the symptoms after Sir John made the first incision.”

“That would be after he had given the hyoscine injection, wouldn’t it?”

Roberts glanced at him sharply.

“Yes, that is true,” he said quickly, “but do you not see, the small amount Sir John injected—a hundredth of a grain, I think it was—would naturally aggravate the condition if hyoscine had already been given?”

“That’s perfectly true,” agreed Alleyn. “It’s an important point, too. Look here, Dr. Roberts, may I take it that it’s your opinion that hyoscine—a fatal amount—was somehow or other got into the man before the operation?”