"Yes, sir."
Mackenzie looked away and stood silent a moment.
"It hardly seems as though I could spare you," and then quickly, "You understand about the calomel and how to use it?"
"Yes."
"And Trevelyan—"
Trevelyan stopped suddenly as he was walking away, and turned.
"Well?"
"And just when the morphia's needed, and when it's judicious to give the opium, calomel and white sugar—and about the salt injections in the veins?"
"Yes."
"And Trevelyan—"