Three Men Proved Yeast Was Alive in 1837. Europe’s Great Chemists Mocked Them.

People had been making wine for thousands of years without knowing what actually did the work. Crush the grapes, wait, and the juice would begin to hiss and foam and turn warm, and in time the sugar was gone and there was wine where there had been must. The froth on top was proof that something was happening. What that something was, nobody could say.¹

The froth even had a name: the ferment, the yeast, the barm skimmed off one batch and stirred into the next. But naming it explained nothing about what it was or what it did. For most of the history of winemaking, the leading guess was that fermentation was a purely chemical event: some unstable substance in the juice, in the act of decaying, passing its own agitation along to the sugar and breaking it down into alcohol and gas. The yeast was scum thrown off by the process, a by-product, not a cause.

Three microscopes, one answer

In 1837 that picture came apart, and it came apart three times at once. In three different countries, three men with microscopes looked hard at yeast and independently reached the same startling conclusion: the stuff was alive.²

In France, the physicist Charles Cagniard-Latour put brewer’s yeast under magnification and saw that the globules were not featureless specks but organised cells that reproduced by budding, throwing off little daughter globules the way a plant throws off shoots. He presented his findings to the Académie des Sciences and argued plainly that these living globules were what drove fermentation.²

In Germany, the physiologist Theodor Schwann, later famous as a founder of cell theory, ran experiments showing that fermentation needed some heat-sensitive agent that ordinary air could not supply, and identified that agent as a living organism. He gave it a name that said exactly what he thought it was: Zuckerpilz, “sugar fungus,” the root of the modern genus name Saccharomyces.² And in a third laboratory the botanist Friedrich Kützing, who studied algae, came to the same view from his own microscope work, suggesting that different fermenting organisms might account for different kinds of fermentation.³

Three specialists, working separately and by different methods, had arrived at the same result. Fermentation was the work of a living organism feeding on the sugar and giving off alcohol and carbon dioxide as it went, not a chemical scum thrown off by decaying juice.

The joke in the journal

This should have been a triumph. Instead it ran straight into the two most powerful chemists in Europe, and they were not amused.

Justus von Liebig, whose laboratory at Giessen trained a generation of chemists, held firmly to the chemical theory of fermentation, in which the process was molecular decay and nothing more. To Liebig and his allies, explaining fermentation by invoking a little living creature was not science but a retreat into mysticism, the sort of vague “vital force” that proper chemistry was supposed to have banished.⁴

In 1839 an anonymous satire appeared in Liebig’s own journal, the Annalen der Pharmacie, ridiculing the living-yeast idea. It is generally attributed to Liebig’s close collaborator Friedrich Wöhler, with Liebig’s full blessing. The piece pretended to describe, in mock-scientific detail, the tiny animals said to be doing the fermenting: creatures shaped like little distilling flasks that swallowed sugar and voided the products at opposite ends, expelling alcohol from below and carbon dioxide from above.⁴

The satire imagined yeast as little animals shaped like distilling flasks, eating sugar and excreting alcohol from one end and carbon dioxide from the other. It was funny, and it was wrong.On the 1839 lampoon in Liebig’s Annalen der Pharmacie

The lampoon was effective. The weight of Liebig’s authority helped push the living-yeast explanation to the margins for the better part of two decades, treated as an embarrassment rather than a discovery.⁴

The last laugh

The vindication came from a chemist who took the biology seriously. Beginning in the 1850s, Louis Pasteur, asked to help a Lille distiller whose fermentations kept going wrong, showed through careful experiment that fermentation was indeed the work of living microorganisms, that different microbes produced different results, and that the sound fermentations depended on healthy yeast.⁵ The 1837 trio had been right all along.

Liebig, for his part, never really surrendered; he went on disputing the point with Pasteur for years, and the argument was still smouldering when he died. But the science had moved. The living-yeast view became the foundation of a new field, microbiology, and in time of the whole modern understanding of fermentation, brewing, and winemaking that follows from it.⁵

Why a wine question mattered so much

The dispute was larger than brewing. The question of what happens in a fermenting vat was one of the places where nineteenth-century science worked out whether living processes obeyed ordinary physical and chemical law or needed some special vital principle of their own. The 1837 discovery, and the fight that followed, helped push biology toward its modern footing.¹

The chemists who wrote and cheered the satire were not fools; they were among the best scientists alive, defending a rigorous idea against what looked like superstition. They were also wrong, and their authority made the field slower to accept a correct result. The froth that everyone had watched for centuries was the answer, and the people best equipped to read it laughed it off.

Related dates

Some of wine’s biggest turning points happened under a microscope, not in the vineyard. Explore what else happened on this article’s date below.

Read more

The science of the vat has a long story: read how wine is actually made, from must to fermentation, meet Louis Pasteur, the chemist who settled the argument, see how his work on wine diseases led to pasteurization, and follow the modern return to wild yeast in the natural wine movement.

References

1. On fermentation as a long-standing mystery, the pre-1837 chemical-decay view of the “ferment,” and the significance of the fermentation question for nineteenth-century biology: general histories of fermentation science. ↩
2. On Charles Cagniard-Latour’s 1837 microscopic demonstration that yeast cells are living and reproduce by budding (presented to the Académie des Sciences), and Theodor Schwann’s independent 1837 identification of a living “sugar fungus” (Zuckerpilz, hence Saccharomyces): histories of the discovery of yeast as a living organism. ↩
3. On Friedrich Kützing’s independent 1837 conclusion that yeasts are living organisms and that different organisms may drive different fermentations: histories of early microbiology. ↩
4. On Justus von Liebig’s chemical theory of fermentation, the resistance to the living-yeast explanation as unscientific “vitalism,” and the 1839 anonymous satire in the Annalen der Pharmacie (generally attributed to Friedrich Wöhler, with Liebig’s backing) mocking yeast as little distilling-flask animals: accounts of the Liebig–yeast controversy. ↩
5. On Louis Pasteur’s work from the 1850s establishing fermentation as the activity of living microorganisms, his vindication of the 1837 view, and Liebig’s continued opposition: histories of Pasteur and of the fermentation debate. ↩

Books worth reading

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Proof: The Science of Booze
Adam Rogers
A lively tour of the science of fermentation and distillation, including what yeast really does and how we came to understand it.

Microbe Hunters
Paul de Kruif
The classic, vivid history of early microbiology, from the first sightings of yeast and microbes through Pasteur’s fermentation work.