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microscope and noticed that the tiny globules of the yeasts he found in them sprouted buds from their sides, buds like seeds sprouting. "They are alive then, these yeasts, they multiply like other creatures," he cried. His further searchings made him see that no brew of hops and barley ever changed into beer without the presence of the yeasts, living growing yeasts. "It must be their life that changes barley into alcohol," he meditated, and he wrote a short clear paper about it. The world refused to get excited about this fine work of the wee yeasts—Cagniard was no propagandist, he had no press agent to offset his own modesty.

In the same year in Germany Doctor Schwann published a short paper in long sentences, and these muddy phrases told a bored public the exciting news that meat only becomes putrid when sub-visible animals get into it. "Boil meat thoroughly and put it in a clean bottle and lead air into it that has passed through red-hot pipes—the meat will remain perfectly fresh for months. But in a day or two after you remove the stopper and let in ordinary air, with its little animals, the meat will begin to smell dreadfully; it will teem with wriggling, cavorting creatures a thousand times smaller than a pinhead—it is these beasts that make meat go bad."

How Leeuwenhoek would have opened his large eyes at this! Spallanzani would have dismissed his congregation and rushed from his masses to his laboratory; but Europe hardly looked up from its newspapers, and young Pasteur was getting ready to make his own first great chemical discovery.

When he was twenty-six years old he made it. After long peerings at heaps of tiny crystals he discovered that there are four distinct kinds of tartaric acid instead of two; that there are a variety of strange compounds in nature that are exactly alike—excepting that they are mirror-images of each other. When he stretched his arms and straightened up his lame back and realized what he had done, he rushed out of his dirty dark little laboratory into the hall, threw his arms around a young physics assistant—he hardly knew him—and