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 on 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. Minnie remained straining out of the window for a minute. Then she drew her head back into the room again. She was dumbfounded. "Of course he is eccentric," she meditated. "But running about London--in the height of the season, too--in his socks!" A happy thought struck her. She hastily put her bonnet on, seized his shoes, went into the hall, took down his hat and light overcoat from the pegs, emerged upon the doorstep, and hailed a cab that opportunely crawled by. "Drive me up the road and round Havelock Crescent, and see if we can find a gentleman running about in a velveteen coat and no hat." "Velveteen coat, ma'am, and no 'at. Very good, ma'am." And the cabman whipped up at once in the most matter-of-fact way, as if he drove to this address every day in his life. Some few minutes later the little group of cabmen and loafers that collects round the cabmen's shelter at Haverstock Hill were startled by the passing of a cab with a ginger-coloured screw of a horse, driven furiously. They were silent as it went by, and then as it receded--"That's 'Arry 'Icks. Wot's _he_ got?" said the stout gentleman known as Old Tootles. "He's a-using his whip, he is, _to_ rights," said the ostler boy.