A gentle rap, a mere light touch of the finger-nails, was heard at the door. The Bacteriologist opened it. "Just a minute, dear," whispered his wife.
When he re-entered the laboratory his visitor was looking at his watch. "I had no idea I had wasted an hour of your time," he said. "Twelve minutes to four. I ought to have left here by half-past three. But your things were really too interesting. No, positively I cannot stop a moment longer. I have an engagement at four."
He passed out of the room reiterating his thanks, and the Bacteriologist accompanied him to the door, and then returned thoughtfully along the passage to his laboratory. He was musing on the ethnology of his visitor. Certainly the man was not a Teutonic type nor a common Latin one. "A morbid product, anyhow, I am afraid," said the Bacteriologist to himself. "How he gloated over those cultivations of disease germs!" A disturbing thought struck him. He turned to the bench by the vapour bath, and then very quickly to his writing-table. Then he felt hastily in his pockets and then rushed to the door. "I may have put it down on the hall table," he said.
"Minnie!" he shouted hoarsely in the hall.
"Yes, dear," came a remote voice.
"Had I anything in my hand when I spoke to you, dear, just now?"
Pause.
"Nothing, dear, because I remember——"
"Blue ruin!" cried the Bacteriologist, and incontinently ran to the front door and down the steps of his house to the street.
Minnie, hearing the door slam violently, ran in alarm to the window. Down the street a slender man was getting into a cab. The Bacteriologist, hatless, and in his carpet slippers, was running and gesticulating wildly towards this group. One slipper came off, but he did not wait for it. "He has gone mad!" said Minnie; "it's that horrid science of his"; and, opening the window, would have called after him. The slender man, suddenly glancing round, seemed struck with the same idea of mental disorder. He pointed hastily to the Bacteriologist, said something to the cabman, the apron of the cab slammed, the whip swished, the horse's feet clattered, and in a moment cab and Bacteriologist hotly in pursuit, had receded up the vista of the roadway and disappeared round the corner.