Ardsley took the dart and examined it for a moment or two. Then he put questions about the state of the bodies and the times, which Sir Clinton was able to furnish.
“H’m!” he said at last. “I think, from what you say, that I might make a guess at it. It’s obviously one of these arrow-poisons or something of that sort; perhaps a strophanthus derivative or a member of the strychnos group.”
“Can you give me anything more definite?” Sir Clinton demanded, rather anxiously. “Time’s the main factor with me just now. I know these vegetable things are the very devil to spot; but it’s honestly a matter of life or death, and I want something definite if you can give me it.”
Ardsley frowned slightly as he examined the dart.
“Can you spare this? I mean, to examine it, chemically—and otherwise. I can’t promise to let you have it back intact, you know.”
“Give me information, that’s all I ask.”
“Very good.”
He paused for a moment.
“You won’t want to let this out of your sight, I suppose. Then you’d better come along to my laboratory. Luckily I have a guinea-pig in stock.”
He glanced under his eyebrows at Wendover.
“You’d rather stay here, I should think, Wendover. You dislike vivisection. I’m only going to put a needle into the little beast—quite painless; but you needn’t come and get your feelings rasped.”
It was phrased politely enough; but it was quite evident from the way in which it was said that Ardsley had no desire to let Wendover into his laboratory. Leaving the Squire to kick his heels, the toxicologist led Sir Clinton through the house to the research department.
“We’d better see exactly what phenomena the poison produces, first of all. I’ll get the guinea-pig.”
He washed some of the poison from the dart with liquid, and introduced the solution into a hypodermic syringe, by means of which he injected a minute amount of the fluid under the guinea-pig’s skin.
“Dead already?” Sir Clinton asked in some astonishment. “It’s like a thunderbolt.”
Ardsley had been experimenting on the animal and watching closely. His face showed that he had found something definite.
“I think I can make a guess,” he said. “It happens to be something with which I’m fairly familiar. Let’s confirm it.”
He made another extraction of the poison which he placed in a test-tube. To this he added a few drops of solution from a bottle which he took down from a shelf.
“Sulphovanadic acid,” he explained. “Just watch.”
On the addition of the reagent, the liquid in the test-tube turned black.
“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 shipshape 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 bloodstream.”
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 noncommittal gesture.
“You practically told me you
