Craig opened a book to a place he had marked.  “Here’s an account of it,” he said.  “Two natives were one day hunting.  They were armed with blow-pipes and quivers full of poisoned darts made of thin, charred pieces of bamboo, tipped with this stuff.  One of them aimed a dart.  It missed the object overhead, glanced off the tree, and fell down on the hunter himself.  This is how the other native reported the result: 

“’Quacca takes the dart out of his shoulder.  Never a word.  Puts it in his quiver and throws it in the stream.  Gives me his blow-pipe for his little son.  Says to me good-bye for his wife and the village.  Then he lies down.  His tongue talks no longer.  No sight in his eyes.  He folds his arms.  He rolls over slowly.  His mouth moves without sound.  I feel his heart.  It goes fast and then slow.  It stops.  Quacca has shot his last woorali dart.’”

Leslie and I looked at Kennedy, and the horror of the thing sank deep into our minds.  Woorali.  What was it?

“Woorali, or curare,” explained Craig slowly, “is the well-known poison with which the South American Indians of the upper Orinoco tip their arrows.  Its principal ingredient is derived from the Strychnos toxifera tree, which yields also the drug nux vomica, which you, Dr. Leslie, have mentioned.  On the tip of that Inca dagger must have been a large dose of the dread curare, this fatal South American Indian arrow poison.”

“Say,” ejaculated Leslie, “this thing begins to look eerie to me.  How about that piece of paper that I sent to you with the warning about the curse of Mansiche and the Gold of the Gods.  What if there should be something in it?  I’d rather not be a victim of this curare, if it’s all the same to you, Kennedy.”

Kennedy was thinking deeply.  Who could have sent the messages to us all?  Who was likely to have known of curare?  I confess that I had not even an idea.  All of them, any of them, might have known.

The deeper we got into it, the more dastardly the crime against Mendoza seemed.  Involuntarily, I thought of the beautiful little Senorita, about whom these terrible events centred.  Though I had no reason for it, I could not forget the fear that she had for Senora de Moche, and the woman as she had been revealed to us in our late interview.

“I suppose a Peruvian of average intelligence might know of the arrow poison of Indians of another country,” I ventured to Craig.

“Quite possible,” he returned, catching immediately the drift of my thoughts.  “But the shoe-prints indicated that it was a man who stole the dagger from the Museum.  It may be that it was already poisoned, too.  In that case the thief would not have had to know anything of curare, would not have needed to stab so deeply if he had known.”

I must confess that I was little further along in the solution of the mystery than I had been when I first saw Mendoza’s body.  Kennedy, however, did not seem to be worried.  Leslie had long since given up trying to form an opinion and, now that the nature of the poison was finally established, was glad to leave the case in our hands.