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superior officers in existence, and Bruce felt himself for the first time a free searcher.

And very soon they made their first step ahead: in the blood of one of their horses, sick to death, Bruce spied a violent unwonted dancing among the faintly yellow, piled-up blood corpuscles; he slid his slide along the stage of his microscope, till he came to an open space in the jungle of blood cells. . . .

There, suddenly, popped into view the cause of the commotion—a curious little beast (much bigger than any ordinary microbe though), a creature with a blunt rear-end and a long slim lashing whip with which he seemed to explore in front of him. A creature shaped like a panatella cigar, only it was flexible, almost tying itself in knots sometimes, and it had a transparent graceful fin running the length of its body. Another of the beasts swam into the open space under the lens, and another. What extraordinary creatures! They didn't go stupidly along like common microbes—they acted like intelligent little dragons. Each one of them darted from one round red blood cell to another; he would worry at it, try to get inside it, tug at it and pull it, push it along ahead of him—then suddenly off he would go in a straight line and bury himself under a mass of the blood cells lining the shore of the open space. . . .

"Trypanosomes—these are!" cried Bruce, and he hurried to show them to his wife. In all animals sick with nagana they found these finned beasts, in the blood they were, and in the fluid of their puffy eyelids, and in the strange yellowish jelly that replaced the fat under their skins. And never a one of them could Bruce find in healthy dogs and horses and cows. But as the sick cattle grew sicker, these vicious snakes swarmed more and more thickly in their blood, until, when the animals lay gasping, next to death, the microbes writhed in them in quivering masses, so that you would swear their blood was made up of nothing else. . . . It was horrible!