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Lazzaro Spallanzani discovered that a microbe split into two

Posted in Historical articles, History, Medicine, Nature, Science on Tuesday, 27 November 2012

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This edited article about Lazzaro Spallanzani originally appeared in Look and Learn issue number 788 published on 19th February 1977.

Spallanzani upon Etna, picture, image, illustration

Lazzaro Spallanzani observing an eruption of Mount Etna by J Armet

Where did microbes come from? If the great learned minds of Europe could establish to their satisfaction the source of these little ‘animals’ first revealed by Dutchman Antony Leeuwenhoek in the 17th century, the mystery of life itself might be laid bare.

However while the Europe of Leeuwenhoek was, by and large, God-fearing and religious, not one hundred years later reaction had set in. In the fashionable salons the powdered gentility of the day liked to believe that God and microbes had nothing at all to do with each other. How absurd to believe that these tiny creatures, visible only through those early microscopes, could be part of some Great Plan.

After all had not that august body, the Royal Society itself, been suitably impressed by a priest called Needham, who appeared to have demonstrated beyond doubt that little animals could generate ‘spontaneously’ in mutton gravy. Since life, therefore, could arise from something as dead as a flask of tightly-corked mutton gravy what need was there for the miraculous hand of the Almighty?

In a dusty, glass-littered laboratory at the University of Reggio in Northern Italy another priest – a Professor into the bargain – thought differently. Lazzaro Spallanzani snorted loudly and indeed publicly – at what he considered to be the nonsensical theories of Needham, and announced to his students that he would demonstrate to this upstart that life could not be generated in mutton gravy, or for that matter in any other soup or concoction, but that it had to grow from other life.

In other words, microbes came from other microbes; flies came from maggots and did not ‘grow’ in garbage; the mice that swarmed beside the fields of the Nile were born of other mice and did not spontaneously create themselves in the river mud.

All his life Spallanzani had wanted to find out the secrets of nature. He had been born in Scandiano, in the north of Italy, in 1729. His father had wanted him to become a lawyer, but young Lazzaro was much more interested in walking in the woods and fields, thinking about the wonder of nature. Unfortunately his inquisitiveness led him, now and again, to pull a few insects apart in order to discover how they ‘worked’, but since this dissection was in the cause of science he must be forgiven that.

He studied mathematics and translated the Classic poets; by the time he was thirty he was established as Professor of Natural Science at the University. He was a flamboyant character, prepared to dazzle his students on the one hand, and then hold court at some fashionable salon where he could further expound his precise and no doubt categoric views.

So how could Needham’s ideas be thoroughly discredited? Spallanzani suspected that there was a simple explanation for the ‘spontaneous’ growth of microbes in Needham’s gravy; the fellow had not corked the bottles tightly enough as a result of which air-borne microbes had entered the flask and – hey presto – begun to multiply happily in the ‘dead’ liquid.

Working as quickly as he could in his laboratory Spallanzani prepared a mixture of pea and almond seeds and pure water – which he knew would provide ‘Fertile soil’ in which microbes could grow – and poured it into a number of flasks. Then he lit some fires and actually fused the necks of some of the flasks. Now and again he yelped and exclaimed in an unpriest-like way as he burned his fingers on the hot glass, but eventually some flasks were sealed in an absolutely air-tight manner. Other flasks Spallanzani corked in the way that Needham had done.

Needham also claimed that he had heated his gravy to make sure that he ‘killed’ any little animals that might have been there to start with. But Spallanzani now wondered whether Needham had heated his mixture long enough?

He put some of his bottles into a steaming cauldron. He kept some of his bottles bobbing up and down in the boiling water for a full hour, while others he heated for only a few minutes.

After that long day Spallanzani wearily put his bottles carefully away – and then deliverately forgot about them. There was time for hunting and fishing, for the salons, for his students and their lectures until the professor decided the moment had come to examine his flasks.

First he carefully cracked open the flasks which he had sealed and then boiled for the full hour. Delicately he transferred samples to his microscope lens, Nothing. Not a sign of life; not one tiny animal.

Next he took the flasks which had been sealed but heated for only a few minutes. Yes, there were some tiny animals, but only a few, and not as large as he had seen at times “How extraordinary,” he thought. “These little animals must have withstood the heat. Evidently to kill them they must be boiled for at least an hour.”

Finally he turned to the corked flasks. With great satisfaction Spallanzani saw that even the bottles which had been boiled for the full hour ‘were like lakes in which swim fishes of all sizes, from whales to minnows. It means that the little animals got into Needham’s flasks from the air . . .’

Although Needham was not to admit defeat at once, it was the beginning of the end for his theories, and for his reputation as a respectable scientist. Meanwhile Spallanzani continued to flourish. Frederick the Great corresponded with him regularly. Maria Theresa, Empress of Austria, offered him a lucrative job at the University of Pavia in Lombardy. After some haggling – Spallanzani was not above such worldly things as feathering his own nest a little – he accepted.

Finally, in one of the most delicate experiments of his life, Spallanzani demonstrated how microbes multiplied.

A Swiss naturalist called de Sassure had first observed through his microscope a very strange phenomenon. It looked to him that now and again, one tiny animal split in half and became two little animals. But other scientists scoffed at this notion. All that was happening, they said, was that little animals were bumping into each other and now and again broke each other in half.

Spallanzani put a drop of water contained microbes on a piece of crystal glass. Next to it, he put a drop of pure distilled water. Looking through the microscope, he made a little canal between the two drops. The first microbe, no more than a few twenty-five thousandths of an inch long, began to swim along the channel.

As it entered the pure water Spallanzani deftly cut the canal with a small camel-hair brush so that no more microbes could follow. He had ‘captured’ one single animal. Now he watched carefully. Sure enough, it began to get thinner in the middle. Then it divided. And later the two halves divided again . . .

That was proof enough. And yet Spallanzani died in 1799 without making the one vital connection – the link between microbes and disease. That would be the work of Louis Pasteur . . .

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