"I suppose they have gradually become accustomed to it," Craig ventured. "If you have ever smoked one particular brand of cigarette you must have noticed how the manufacturer can gradually substitute a cheaper grade of tobacco without any large number of his patrons knowing anything about it. I imagine it might have been done in some way like that."
"But you would think they'd feel the effect and attribute it to smoking."
"Perhaps they do feel the effect. But when it comes to tracing causes, some people are loath to admit that tobacco and liquor can be the root of the evil. No, some one is slipping these cigarettes in on them, perhaps substituting the doped brand for those that are ordered. If you will notice, both Whitney and Lockwood have cigarettes that are made especially for them. So had Mendoza. It is a circumstance which some one has turned to account, though how and by whom the substitution has been made I cannot say yet. I wish I had time to follow out this one line, to the exclusion of everything else. But I've got to keep my fingers on every rope at once, else the thing will pull away from me. It is enough for the present that we know what the poison is. I shall take up the tracing of the person who is administering it the moment I get a hint."
It was almost daylight before Craig and I left the laboratory after his discovery of the manner of the cigarette poisoning by stramonium. But that was the only way in which he was able to make progress—taking time for each separate point by main force.
I was thoroughly tired, though not so much so that my dreams were not haunted by a succession of baleful eyes peering at me from the darkness.
I slept late, but was awakened by a knocking on the door. As I rose to answer it I saw through the open door of Kennedy's room that he had been about early and must already be at the laboratory. How he did it I don't know. My own newspaper experience had made me considerable of a nighthawk. But I always paid for it by sleeping the next day. With Kennedy, when he was on a case, even five hours of sleep was more than he seemed able to stand.
"Hello, Jameson," greeted a voice, as I opened the door. "Is Kennedy in—oh, he hasn't come back yet?"
It was Lockwood, at first eager to see Craig, then naturally crestfallen because he saw that he was not there.
"Yes," I replied, rubbing my eyes. "He must be at the laboratory. If you'll wait a minute while I slip on my clothes, I'll walk over there with you."
While I completed my hasty toilet, Lockwood sat in our living room, gazing about with fascination at the collection of trophies of the chase of criminals.