So he proved, after a fashion, that this new kind of beast was another kind of ferment, a ferment that made the rancid-butter-acid from sugar; but he didn’t nail down his proof, because he couldn’t be sure, absolutely, that there was one kind and only one kind of beast present in his bottles. While he was a little confused and uncertain about this, he turned his troubles once more to his advantage. He was peering, one day, at the rancid butter microbes swarming before his microscope. “There’s something new here--in the middle of the drop they are lively, going every which way.” Gently, precisely, a little aimlessly, he moved the specimen so that the edge of the drop was under his lens.... “But here at the edge they’re not moving, they’re lying round stiff as pokers.” It was so with every specimen he looked at. “Air kills them,” he cried, and was sure he had made a great discovery. A little while afterward he told the Academy proudly that he had not only discovered a new ferment, a wee animal that had a curious trick of making stale-butter-acid from sugar, but besides this he had discovered that these animals could live and play and move and do their work without any air whatever. Air even killed them! “And this,” he cried, “is the first example of little animals living without air!” Unfortunately it was the third example. Two hundred years before old Leeuwenhoek had seen the same thing. A hundred years later Spallanzani had been amazed to find that microscopic beasts could live without breathing. Very probably Pasteur didn’t know about these discoveries of the old trail blazers--I am sure he was not trying to steal their stuff--but as he went up in his excited climb toward glory and toward always increasing crowds of new discoveries, he regarded less and less what had been done before him and what went on around him. He re-discovered the curious fact that microbes make meat go bad. He failed to give the first discoverer, Schwann, proper credit for it!