“You mean to tell me,” I said, “that it is possible to differentiate a substance produced synthetically in the laboratory from one produced by living tissue?”
“Certainly,” said Waters, turning to me in some surprise, but apparently accepting my tardy realisation of this truth as mere vagary of my slow and unscientific wits. “So long, of course, as the artificial substance remains in the first or racemic form, for this would be optically inactive, while that from the living tissues would rotate the beam of polarised light, when viewed in the polariscope. If, however, that racemic form had been already split up by the intelligent operator, or some other living agency, into its two dextro- and laevo-rotary forms, it would be impossible to distinguish between them.”
I saw a path of escape opening up. Surely the synthetic muscarine at St. Anthony’s would have had this other operation performed on it. There was no reason at all why I should interfere. I relapsed into silence, and the conversation wandered on.
I was recalled to myself by a movement about me. Matthews was explaining that he had to be getting home. Waters rose to accompany him. In a minute he would be gone and the opportunity lost. I had only to sit still.
I got up. I made my fatuous farewells. I said I had a perfectly good wife to go home to. I thanked my host and said how much I had enjoyed the evening. I followed the other men out into the narrow hall, with its loaded umbrella-stand and ugly, discoloured wallpaper.
“ Dr. Waters,” I said.
“Yes?” He turned smiling towards me. I must say something now or he would think me a fool.
“May I have a word with you?”