"Which is it to-day?" I asked,-"morphine or cocaine?"
He raised his eyes languidly from the old black-letter volumewhich he had opened. "It is cocaine," he said,-"a seven-per-cent.
solution. Would you care to try it?"
"No, indeed," I answered, brusquely. "My constitution has not gotover the Afghan campaign yet. I cannot afford to throw any extrastrain upon it."
He smiled at my vehemence. "Perhaps you are right, Watson," hesaid. "I suppose that its influence is physically a bad one. I find it,
however, so transcendently stimulating and clarifying to the mindthat its secondary action is a matter of small moment."
"But consider!" I said, earnestly. "Count the cost! Your brain may,
as you say, be roused and excited, but it is a pathological andmorbid process, which involves increased tissue-change and mayat last leave a permanent weakness. You know, too, what a black