Fermentation

Fermentation has played two distinct roles in the history of medicine, separated by two centuries but connected by a single question: is the transformation of organic matter a chemical process or a biological one? In the seventeenth century, Helmontian physicians proposed that digestion, metabolism, and disease were species of fermentation, governed by immaterial ferments within the body. In the nineteenth century, Pasteur proved that fermentation itself was the work of living micro-organisms, not a purely chemical reaction — a discovery that laid the foundation for germ theory and antiseptic surgery. The concept thus bridges the chemical medicine of the early modern period and the bacteriology of the modern.

Fermentation as Vital Process (Seventeenth Century)

For Van Helmont and the Helmontian iatrochemists, fermentation was the fundamental process of life. The archeus governed bodily chemistry through a hierarchy of ferments, each specific to an organ and a function. Digestion was fermentation directed by the gastric archeus; growth was fermentation directed by the organ-specific archei; disease was fermentation gone wrong (Driesch, 1914).

This was a conceptual advance over Galenic concoction, which explained digestion as the result of innate heat acting on food. Fermentation provided a chemical mechanism — or at least a chemical metaphor — for processes that Galenism had explained only by appealing to qualities. But the Helmontian ferments were not the enzymes of modern biochemistry. They were immaterial principles, closer to Aristotelian forms than to protein catalysts.

When Sylvius systematized iatrochemistry, he retained the language of fermentation but stripped it of vitalist content. In Sylvius’s system, bodily fermentation was a clash of acids and alkalis — a chemical process explicable without any directing intelligence (Coulter, 1975). The ferment was demoted from a vital principle to a chemical reagent.

Fermentation and Germ Theory (Nineteenth Century)

The question of whether fermentation was chemical or biological returned with new urgency in the mid-nineteenth century. Justus von Liebig, the dominant chemist of the era, insisted that fermentation was a purely chemical process. When Cagniard de Latour presented evidence in 1836 that yeast was a living organism responsible for fermentation, Liebig’s chemical authority successfully overrode the finding. Ackerknecht notes that the germ theory was “at the lowest ebb in its history” when Henle proclaimed it in 1840, and that even clear evidence for living organisms in fermentation could be dismissed (Ackerknecht, 1955).

Pasteur examined wine vat samples under his microscope (Fitzharris, 2017). He found that unspoiled wine contained round yeast cells, while corrupted wine contained elongated yeast and rod-shaped bacteria (Fitzharris, 2017). He concluded that fermentation was a biological process and that yeast was a living organism (Fitzharris, 2017).

Pasteur was not a medical man but a chemist. He proved fermentation was biological (1857), disproved spontaneous generation (1862), saved French industries from silk, wine, and beer diseases, and only in 1877 extended his work to human disease (Ackerknecht, 1955). The path from fermentation to germ theory was not direct; it ran through industrial microbiology before reaching the clinic.

Writing in 1918, Henry Lindlahr reported that “impartial investigators” claimed Pasteur had appropriated many of his foundational ideas from Antoine Béchamp, whose microzyma theory proposed that fermentation could arise from sub-microscopic living units already present within fluids, without airborne contamination.(Lindlahr, Henry, 1918) Lindlahr presented this as an unresolved scientific dispute: Pasteur maintained that organisms in the air were required to initiate fermentation in preserved living fluids; Béchamp argued for an endogenous source. This rival account of fermentation’s origin had direct implications for germ theory — if fermentation could arise internally, infection need not require external contagion — and it remained a point of reference for vitalist medicine well into the twentieth century.

Fermentation, Putrefaction, and Surgery

The connection between fermentation and surgical practice came through the concept of putrefaction. If fermentation was caused by micro-organisms, then putrefaction — the rotting of wounds that killed so many surgical patients — might be caused by micro-organisms too. In late 1864, chemistry professor Thomas Anderson drew Joseph Lister’s attention to Pasteur’s research on fermentation and putrefaction. Fitzharris identifies this as the decisive intellectual turning point toward Lister’s antiseptic system (Fitzharris, 2017).

Lister reasoned that if micro-organisms caused wound putrefaction, then killing those organisms should prevent it. Carbolic acid became his antiseptic agent, and the dramatic reduction in surgical mortality that followed provided clinical proof of the germ theory before Koch’s laboratory work formalized it.

The irony is that the seventeenth-century Helmontians had been right that bodily processes were fermentative in nature — but wrong about the mechanism. Fermentation was biological, as they had intuited, but the agents were micro-organisms, not immaterial archei.

See Also

• Archeus
• Iatrochemistry
• Bacteriology
• Louis Pasteur
• Germ Theory
• Jan Baptist van Helmont
• Joseph Lister
• Putrefaction

Sources

All claims cite evidence cards from:

• Coulter, H.L. (1975). Divided Legacy. Washington, DC: Wehawken. [Source ID: coulter-divided-legacy-1975]
• Driesch, H. (1914). The History and Theory of Vitalism. London: Macmillan. [Source ID: driesch-historyvitalism-1914]
• Ackerknecht, E.H. (1955). A Short History of Medicine. New York: Ronald Press. [Source ID: ackerknecht-shorthistory-1955] — Lead authority
• Fitzharris, L. (2017). The Butchering Art. New York: Scientific American. [Source ID: fitzharris-the-butchering-art-2017]