“It ought to change to dark blue, and then to red after a time.”
“What do you make of it?” Sir Clinton demanded.
“Curare. I’m pretty sure of it. I’ve used it a lot and I feel fairly safe in saying that. Of course, if you want me to swear to it, that’s a different matter. This is only a rough test. I’d need to do a lot more before I could go into the box and testify about it.”
Sir Clinton nodded.
“Of course, I know it by name,” he said. “South American arrow poison, isn’t it? Can you tell me anything more about it?”
Ardsley was engaged in writing some notes. He looked up apologetically for a moment.
“I have to enter up details of each experiment I carry out, you know, Sir Clinton—even if it’s only a case of pricking a beast with a needle. If you don’t mind, I’ll finish this entry. I like to have things always ship-shape in that line, and the more so since I’ve got the police on the premises.”
He smiled, not altogether pleasantly, as he turned again to his writing. When he had finished, he suggested that they should rejoin Wendover.
“I’m not going to give you a lecture on curare,” he said, when they had returned to the other room, “but one or two points may be of use to you. It’s a South American arrow poison, as you said. Its physiological effect is a powerful paralysing action on the motor nerve endings supplying striated muscle, but it has no action on the excitability of the muscle. You saw the actual results in that experiment.”
“I guessed something of the sort from the state of the two bodies,” Sir Clinton explained. “It was pretty clear that neither of them had struggled much before they died. I put that down to the swift action of the poison; but from what you say, they must have been paralysed when the stuff got into the blood-stream.”