“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.” Ardsley made no comment, but continued his exposition. “It wouldn’t require a large dose to kill a man. Curare contains various alkaloids. Paracurarine and protocurarine are amongst them. A quarter of a grain of protocurarine would kill a ten-stone man quite easily. There was far more than a fatal dose of curare on that dart.” “Can you tell us anything about how the stuff comes on the market?” Sir Clinton inquired. “There are three brands of it to be had,” the toxicologist explained. “Para curare you can buy in bamboo tubes; calabash curare is packed in gourds; and what they call pot curare is sold in earthenware pots. The stuff’s a crude product, you understand. One specimen differs from another to some extent, though not materially for most purposes.” “You have some of it in stock yourself for your experiments, perhaps?” Ardsley smiled rather grimly. “A man isn’t required to incriminate himself, is he? But I don’t mind admitting that I have some of the stuff. You could have found that out for yourself by examining my returns under the Act, you know, so I lose nothing by frankness.” Sir Clinton acknowledged the underlying meaning of Ardsley’s words by a faint shrug of his shoulders, a completely non-committal gesture.