Then suddenly Spallanzani had his chance, for Needham made an objection to one of his experiments. “Your experiment does not hold water,” he wrote to the Italian, “because you have heated your flasks for an hour, and that fierce heat weakens and so damages the Vegetative Force that it can no longer make little animals.” This was just what the energetic Spallanzani was waiting for, and he forgot religion and large classes of eager students and the pretty ladies that loved to be shown through his museum. He rolled up his wide sleeves and plunged into work, not at a writing desk but before his laboratory bench, not with a pen, but with his flasks and seeds and microscopes. IV “So Needham says heat damages the Force in the seeds, does he? Has he tried it? How can he see or feel or weigh or measure this Vegetative Force? He says it is in the seeds, well, we’ll heat the seeds and see!” Spallanzani got out his flasks once more and cleaned them. He brewed mixtures of different kinds of seeds, of peas and beans and vetches with pure water, until his work room almost ran over with flasks--they perched on high shelves, they sat on tables and chairs, they cluttered the floor so it was hard to walk around. “Now, we’ll boil a whole series of these flasks different lengths of time, and see which one generates the most little animals,” he said, and then doused one set of his soups in boiling water for a few minutes, another for a half hour, another for an hour, and still another for two hours. Instead of sealing them in the flame he plugged them all up with corks--Needham said that was enough--and then he put them carefully away to see what would happen. He waited. He went off fishing and forgot to pull up his rod when a fish bit, he collected minerals for his museum, and forgot to take them home with him. He plotted for higher pay, he said masses, and studied the copulation of frogs and toads--and then disappeared once more to his dim work room with its regiments of bottles and weird machines. He waited. If Needham were right, the flasks boiled for minutes should be alive with little animals, but the ones boiled for an hour or two hours should be deserted. He pulled out the corks one by one, and looked at the drops of soup through his lens and at last laughed with delight--the bottles that had been boiled for two hours actually had more little animals sporting about in them than the ones he had heated for a few minutes. “Vegetative Force, what nonsense! so long as you only plug up your flasks with corks the little animals will get in from the air. You can heat your soups till you’re black in the face--the microbes will get in just the same and grow, after the broth has cooled.”