Many people objected to this scornful cockiness--but some good men of science had better reasons for disagreeing with him--his experiments were brilliant, they were startling, but his experiments stopped short of being completely proved. They had loopholes. Every now and then when he set out confidently with some of his gray specks of ferment to make the acid of sour milk, he would find to his disgust a nasty smell of rancid butter wafting up from his bottles. There would be no little rods in the flask--alas--and none of the sour-milk-acid that he had set out to get. These occasional failures, the absence of sure-fire in these tests gave ammunition to his enemies and brought sleepless nights to Pasteur. But not for long! It is not the least strange thing about him that it didn’t seem to matter to him that he never quite solved this confusing going wrong of his fermentations; he was a cunning man--instead of butting his head against the wall of this problem, he slipped around it and turned it to his great fame and advantage. [Illustration: PASTEUR AT FORTY-FIVE] Why this annoying rancid butter smell--why sometimes no sour-milk-acid? One morning, in one of his bottles that had gone bad, he noticed another kind of wee beasts swimming around among a few of the discouraged dancing rods which should have been there in great swarms. “What are these beasts? They’re much bigger than the rods--they don’t merely quiver and vibrate--they actually swim around like fish; they must be little animals.” He watched them peevishly, he had an instinct they had no business there. There were processions of them hooked together like barges on the River Seine, strings of clumsy barges that snaked along. Then there were lonely ones that would perform a stately twirl now and again; sometimes they would make a pirouette and balance--the next moment they would shiver at one end in a curious kind of shimmy. It was all very interesting, these various pretty cavortings of these new beasts. But they had no business there! He tried a hundred ways to keep them out, ways that would seem very clumsy to us now, but just as he thought he had cleaned them out of all his bottles, back they popped. Then one day it flashed over him that every time that his bottles of soup swarmed with this gently moving larger sort of animal, these same bottles of soup had the strong nasty smell of rancid butter.