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air in sealed up flasks? Could this windbag knock out all of this careful finding of facts, which had taken so many years of hard work? For days Spallanzani went about troubled, and snapped at students to whom before he had been gentle, and tried to comfort himself by reciting Dante and Homer—and this only made him more grumpy. A relentless torturing imp pricked at him and this imp said: "Find out why the air rushes into your flasks when you break the seals—it may not have anything to do with elasticity." The imp woke him up in the night, it made him get tangled up in his masses. . . .

Then like a flash of lightning the explanation came to him and he hurried to his work bench—it was covered with broken flasks and abandoned bottles and its muddled disarray told his discouragement—he reached into a cupboard and took out one of his flasks. He was on the track, he would show Needham was wrong, and even before he had proved it he stretched himself with a heave of relief—so sure was he that the reason for the little whistling of air had come to him. He looked at the flasks, then smiled and said, "All the flasks that I have been using have fairly wide necks. When I seal them in the flame it takes a lot of heat to melt the glass till the neck is shut off—all that heat drives most of the air out of the bottle before it's sealed up. No wonder the air rushes in when I crack the seal!"

He saw that Needham's idea that boiling water outside the flask damaged the elasticity of the air inside was nonsense, nothing less. But how to prove this, how to seal up the flasks without driving out the air? His devilish ingenuity came to help him, and he took another flask, put seeds into it, and filled it partly with pure water. Then he rolled the neck of the bottle around in a hot flame until it melted down to a tiny narrow opening—very, very narrow, but still open to the air outside. Next he let the flask cool—now the air inside must be the same as the air outside—then he applied a tiny flame to the now almost needle-fine opening. In a jiffy the flask was sealed—without expelling any of the air from the inside. Con-