"What is pilocarpin?" she asked, making a difficulty of the word.
"It is really a sort of eye dope," he explained. "You know atropin--the stuff an oculist uses in your eyes when he wants to examine them--leaves your vision blurred for a day or so."
"Yes, I know that."
"The effect of atropin is to expand the pupil. Pilocarpin is just the opposite--it contracts the pupil."
"What need could you possibly have of that?"
"There's the joke: I haven't. But when I was outfitting I could not get near enough phenacetin. I suppose you know that we use phenacetin to induce sweating as first treatment of fever."
"I am not entirely ignorant. I can treat fevers, of course."
"Well, I took all they could spare. Then McCloud suggested pilocarpin. Though it is really an eye drug, to be used externally, it also has an effect internally to induce sweating. So that's why I have it."
She was examining the bottles.
"But you have atropin also. Why is that?"