jan baptista van helmont experiment performed in spontaneous generation

3.1 Spontaneous Generation

Learning objectives.

By the end of this section, you will be able to:

• Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms
• Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation

Clinical Focus

Barbara is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Barbara began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Barbara’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak.

• What types of respiratory disease may be responsible?

Jump to the next Clinical Focus box

Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages.

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation , the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“spirit” or “breath”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. 1

This theory persisted into the 17th century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont , a 17th century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish.

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers ( Figure 3.2 ). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation.

In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. 2 He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes.

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. 3 As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation ( Figure 3.3 ).

Check Your Understanding

• Describe the theory of spontaneous generation and some of the arguments used to support it.
• Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.

Disproving Spontaneous Generation

The debate over spontaneous generation continued well into the 19th century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur , a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms.

Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it ( Figure 3.4 ). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth.

Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “…life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” 4 To Pasteur’s credit, it never has.

• How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important?
• What was the control group in Pasteur’s experiment and what did it show?
• 1 K. Zwier. “Aristotle on Spontaneous Generation.” http://www.sju.edu/int/academics/cas/resources/gppc/pdf/Karen%20R.%20Zwier.pdf
• 2 E. Capanna. “Lazzaro Spallanzani: At the Roots of Modern Biology.” Journal of Experimental Zoology 285 no. 3 (1999):178–196.
• 3 R. Mancini, M. Nigro, G. Ippolito. “Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.” Le Infezioni in Medicina 15 no. 3 (2007):199–206.
• 4 R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142.

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Microbe Notes

Experiments in support and against Spontaneous Generation

• Spontaneous generation is an obsolete theory which states that living organisms can originate from inanimate objects.
• The theory believed that dust created fleas, maggots arose from rotting meat, and bread or wheat left in a dark corner produced mice among others.
• Although the idea that living things originate from the non-living may seem ridiculous today, the theory of spontaneous generation was hotly debated for hundreds of years.
• During this time, many experiments were conducted to both prove and disprove the theory.

Table of Contents

Interesting Science Videos

Experiments in Support of Spontaneous Generation

The doctrine of spontaneous generation was coherently synthesized by Aristotle, who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms, and was taken as scientific fact for two millennia.

• The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation, the notion that life can arise from nonliving matter. 
• Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”).
• As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water.

John Needham

• The English naturalist John Turberville Needham was in support of the theory.
• Needham found that large numbers of organisms subsequently developed in prepared infusions of many different substances that had been exposed to intense heat in sealed tubes for 30 minutes.
• Assuming that such heat treatment must have killed any previous organisms, Needham explained the presence of the new population on the grounds of spontaneous generation.
• By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding.
• Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared.
• Jan Baptista van Helmont , a seventeenth century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks.

Experiments against Spontaneous Generation

Though challenged in the 17th and 18th centuries by the experiments of Francesco Redi and Lazzaro Spallanzani, spontaneous generation was not disproved until the work of Louis Pasteur and John Tyndall in the mid-19th century.

Francesco Redi

• The Italian physician and poet Francesco Redi was one of the first to question the spontaneous origin of living things.
• Having observed the development of maggots and flies on decaying meat, Redi in 1668 devised a number of experiments, all pointing to the same conclusion: if flies are excluded from rotten meat, maggots do not develop. On meat exposed to air, however, eggs laid by flies develop into maggots. 
• He tested the spontaneous creation of maggots by placing fresh meat in each of two different jars.
• One jar was left open; the other was covered with a cloth. Days later, the open jar contained maggots, whereas the covered jar contained no maggots.
• He did note that maggots were found on the exterior surface of the cloth that covered the jar. Redi successfully demonstrated that the maggots came from fly eggs.

Lazzaro Spallanzani

• The experiments of Needham appeared irrefutable until the Italian physiologist Lazzaro Spallanzani repeated them and obtained conflicting results.
• He published his findings around 1775, claiming that Needham had not heated his tubes long enough, nor had he sealed them in a satisfactory manner.
• Although Spallanzani’s results should have been convincing, Needham had the support of the influential French naturalist Buffon; hence, the matter of spontaneous generation remained unresolved.

Louis Pasteur

• Louis Pasteur ‘s 1859 experiment is widely seen as having settled the question of spontaneous generation.
• He boiled a meat broth in a flask that had a long neck that curved downward, like that of a goose or swan.
• The idea was that the bend in the neck prevented falling particles from reaching the broth, while still allowing the free flow of air.
• The flask remained free of growth for an extended period. When the flask was turned so that particles could fall down the bends, the broth quickly became clouded.
• This work was so conclusive; that biology codified the “Law of Biogenesis,” which states that life only comes from previously existing life.

John Tyndall

• Support for Pasteur’s findings came in 1876 from the English physicist John Tyndall, who devised an apparatus to demonstrate that air had the ability to carry particulate matter.
• Because such matter in air reflects light when the air is illuminated under special conditions, Tyndall’s apparatus could be used to indicate when air was pure.
• Tyndall found that no organisms were produced when pure air was introduced into media capable of supporting the growth of microorganisms.
• It was those results, together with Pasteur’s findings, that put an end to the doctrine of spontaneous generation.
• Parija S.C. (2012). Textbook of Microbiology & Immunology.(2 ed.). India: Elsevier India.
• Sastry A.S. & Bhat S.K. (2016). Essentials of Medical Microbiology. New Delhi : Jaypee Brothers Medical Publishers.
• https://study.com/academy/lesson/spontaneous-generation-definition-theory-examples.html
• https://www.britannica.com/science/biology#ref498783
• https://www.infoplease.com/science/biology/origin-life-spontaneous-generation
• https://www.allaboutscience.org/what-is-spontaneous-generation-faq.htm
• https://courses.lumenlearning.com/microbiology/chapter/spontaneous-generation/

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Spontaneous Generation

Learning objectives.

• Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms
• Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation

Clinical Focus: Anika, Part 1

Anika is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Anika began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Anika’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak.

• What types of respiratory disease may be responsible?

We’ll return to Anika’s example in later pages.

Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages.

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation , the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. [1]

This theory persisted into the seventeenth century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont , a seventeenth century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish.

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers (Figure 1). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation.

Figure 1. Francesco Redi’s experimental setup consisted of an open container, a container sealed with a cork top, and a container covered in mesh that let in air but not flies. Maggots only appeared on the meat in the open container. However, maggots were also found on the gauze of the gauze-covered container.

In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. [2]  He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes.

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. [3]  As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation (Figure 2).

Figure 2. (a) Francesco Redi, who demonstrated that maggots were the offspring of flies, not products of spontaneous generation. (b) John Needham, who argued that microbes arose spontaneously in broth from a “life force.” (c) Lazzaro Spallanzani, whose experiments with broth aimed to disprove those of Needham.

Think about It

• Describe the theory of spontaneous generation and some of the arguments used to support it.
• Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.

Disproving Spontaneous Generation

The debate over spontaneous generation continued well into the nineteenth century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur, a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms.

Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it (Figure 3). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth.

Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” [4]  To Pasteur’s credit, it never has.

Figure 3. (a) French scientist Louis Pasteur, who definitively refuted the long-disputed theory of spontaneous generation. (b) The unique swan-neck feature of the flasks used in Pasteur’s experiment allowed air to enter the flask but prevented the entry of bacterial and fungal spores. (c) Pasteur’s experiment consisted of two parts. In the first part, the broth in the flask was boiled to sterilize it. When this broth was cooled, it remained free of contamination. In the second part of the experiment, the flask was boiled and then the neck was broken off. The broth in this flask became contaminated. (credit b: modification of work by “Wellcome Images”/Wikimedia Commons)

• How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important?
• What was the control group in Pasteur’s experiment and what did it show?

Key Concepts and Summary

• The theory of spontaneous generation states that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks.
• Experimentation by Francesco Redi in the seventeenth century presented the first significant evidence refuting spontaneous generation by showing that flies must have access to meat for maggots to develop on the meat. Prominent scientists designed experiments and argued both in support of (John Needham) and against (Lazzaro Spallanzani) spontaneous generation.
• Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that “life only comes from life.”

Multiple Choice

Which of the following individuals argued in favor of the theory of spontaneous generation?

• Francesco Redi
• Louis Pasteur
• John Needham
• Lazzaro Spallanzani

Which of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask?

• Jan Baptista van Helmont

Which of the following experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation.

• Antonie van Leeuwenhoek

Fill in the Blank

The assertion that “life only comes from life” was stated by Louis Pasteur in regard to his experiments that definitively refuted the theory of ___________.

Exposure to air is necessary for microbial growth.

• Explain in your own words Pasteur’s swan-neck flask experiment.
• Explain why the experiments of Needham and Spallanzani yielded in different results even though they used similar methodologies.
• What would the results of Pasteur’s swan-neck flask experiment have looked like if they supported the theory of spontaneous generation?

Candela Citations

• OpenStax Microbiology. Provided by : OpenStax CNX. Located at : http://cnx.org/contents/[email protected] . License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/contents/[email protected]
• K. Zwier. "Aristotle on Spontaneous Generation." http://www.sju.edu/int/academics/cas/resources/gppc/pdf/Karen%20R.%20Zwier.pdf ↵
• E. Capanna. "Lazzaro Spallanzani: At the Roots of Modern Biology." Journal of Experimental Zoology 285 no. 3 (1999):178–196. ↵
• R. Mancini, M. Nigro, G. Ippolito. "Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation." Le Infezioni in Medicina 15 no. 3 (2007):199–206. ↵
• R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142. ↵

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Jan Baptist van Helmont: alchemist, physiologist, physician

• October 2, 2024 October 7, 2024

Jan Baptist van Helmont, born in Brussels in 1580, was a chemist, physiologist, and physician whose work helped shape the future of modern science.

Discovering Belgium reader Mansur Sultani recently suggested that I write about the remarkable life and work of Jan Baptist van Helmont. So here is my profile of this 17th-century thinker who transformed the fields of chemistry and medicine. His work resonates with scientific principles still in use today.

Introduction: The man who bridged alchemy and chemistry

A philosopher, physician, chemist, and alchemist, van Helmont is perhaps best known for his pioneering experiments that contributed to the birth of chemistry as a distinct scientific discipline. Although deeply influenced by the mystical and spiritual leanings of alchemy, van Helmont used experimentation and observation in ways that anticipated the scientific method. His insights into gases, physiology, and medicine had lasting effects on future generations of scientists, including Robert Boyle and Antoine Lavoisier .

Early life: A journey from wealth to wonder

Jan Baptist van Helmont was born on 12 January, 1580 in Brussels (part of the Spanish Netherlands at the time) into a wealthy and influential Flemish family. He was the youngest of five children of Maria van Stassaert and Christiaen van Helmont, a public prosecutor and Brussels council member.

His early education reflected the humanist ideals of the time, with a classical curriculum focusing on Latin, philosophy, and theology. Although his family encouraged him to pursue a career in law, van Helmont had little interest in this path.

After brief studies in law at the University of Leuven, he shifted his focus to medicine and obtained a medical degree in 1599. His dissatisfaction with the traditional, Galenic understanding of medicine, which revolved around the balance of bodily humors, led him on a quest for a more empirical and holistic understanding of the natural world. This desire would shape the rest of his life, as van Helmont set out to redefine what science and medicine could achieve.

A research lab in Neder-over-Heembeek

He practiced at Antwerp at the time of the great plague in 1605, after which he wrote a book titled De Peste (The Plague), which was reviewed by Newton in 1667. In 1609 he married Margaret van Ranst, who was of a wealthy noble family. Van Helmont and Margaret lived in Vilvoorde and had six or seven children. The inheritance of his wife (and from his father who died in 1580) enabled him to retire early from his medical practice and occupy himself with research for the rest of his life.

He had a laboratory built in Neder-over-Heembeek, close to the Church of Saints Peter and Paul. Unfortunately, the house he lived in no longer exists. However, a nearby street is named in his memory: La Venelle de l’Alchimiste (Alchemist’s Alley).

A radical thinker: Early influences and the draw of alchemy

Alchemy, a discipline blending spiritual and material exploration, was an early influence on van Helmont’s intellectual life. He was drawn to the Hermetic tradition, which saw the natural world as a source of hidden, mystical truths. However, van Helmont was no mere mystic. He believed that the path to unlocking nature’s secrets lay in rigorous experimentation and careful observation.

This combination of spiritual belief and experimental practice set him apart from many of his contemporaries. Van Helmont saw alchemy not simply as a means of transmuting base metals into gold, but as a way to understand the deeper workings of matter and life itself. His writings often blended theological reflection with scientific inquiry, a reflection of the deeply religious context in which he worked.

The birth of modern chemistry: van Helmont’s revolutionary ideas

One of van Helmont’s most significant contributions was his exploration of gases, which he referred to as “gas” (a term he coined, from the Greek word “chaos”). This was revolutionary, as gases were largely misunderstood at the time. His famous experiment involving the burning of charcoal showed that a substance was released during combustion, which he called “ gas sylvestre ,” or what we now recognize as carbon dioxide.

In another key experiment, van Helmont sought to disprove the idea of spontaneous generation and the old theory that all matter derived from the four elements – earth, water, air, and fire. He planted a willow tree in a pot containing a fixed amount of soil, carefully measuring the water he added. After five years, the tree had gained a significant amount of mass, yet the soil had barely decreased in volume. From this, van Helmont concluded that the growth of the tree came from water, not soil, laying the groundwork for future investigations into plant physiology and the role of photosynthesis.

Although he began as a follower of Paracelsus , van Helmont rejected many of his theories and refused to accept the Paracelsian first principles (sulphur, salt, and mercury) as pre-existent in matter, believing instead that sulphur, salt and mercury were products of reactions that involved heat.

Medicine and physiology: A pioneer in health sciences

Van Helmont was also a physician, and his contributions to medicine were significant. In an age when humoral theory (the idea that the body was governed by four fluids: blood, yellow bile, black bile, and phlegm) still dominated medical thought, van Helmont introduced a new way of thinking about illness and health.

He rejected the humoral theory and believed that diseases were caused by specific external agents, which was a radical departure from the prevailing ideas of the time. He was an early proponent of “iatrochemistry,” a field that sought to explain physiological processes and diseases in terms of chemical reactions within the body.

In 1609, van Helmont used chemical methods to study bodily products such as urine and blood. He studied the human body and its functions, and applied his findings as a way of understanding and curing the body. Van Helmont experimented with treatments that we now consider part of early pharmaceutical science, using chemicals such as mercury, sulfur, and various salts to treat patients. His work laid the foundation for the field of biochemistry and introduced concepts that would later evolve into the germ theory of disease.

A theological scientist: Balancing faith and experimentation

For van Helmont, the pursuit of scientific knowledge was deeply intertwined with his religious beliefs. He viewed nature as a divine creation and believed that through understanding the natural world, one could draw closer to understanding God. However, this blending of science and spirituality led to conflict with established authorities, particularly the Catholic Church.

At that time, Pope Urban VIII was the reigning pope. His reign was marked by a mixture of political, scientific, and theological challenges, and he is perhaps best known for his involvement in the trial of Galileo Galilei .

During this period, the Catholic Church was still closely monitoring scientific ideas that conflicted with traditional theological doctrine, especially if those ideas seemed to challenge church teachings. Van Helmont’s unorthodox medical and theological views caught the attention of Pope Urban VIII. In 1625, van Helmont was imprisoned by the Inquisition for publishing heretical views. Thankfully, van Helmont was eventually released and continued his scientific and medical work afterwards.

Despite these conflicts, van Helmont maintained his belief in a harmonious relationship between faith and reason. His works often reflected a desire to reconcile the mystical and empirical aspects of knowledge.

Legacy: The bridge between alchemy and science

Jan Baptist van Helmont died on 30 December 1644 at the age of 64. His legacy is that of a thinker who lived at the cusp of two intellectual worlds – alchemy and modern science. His work laid the groundwork for future chemists, including Robert Boyle, who is often credited with founding modern chemistry, and Antoine Lavoisier, who later refined the study of gases.

His son Franciscus Mercurius van Helmont (1614-1698) was an alchemist and writer. He is best known for his publication in the 1640s of his father’s pioneer works on chemistry, which link the origins of the science to the study of alchemy.

Although van Helmont’s theories were not always correct – he still believed in the existence of certain mystical forces – his empirical approach to understanding the natural world was ahead of its time. His work on gases, plant growth, and the chemical causes of disease paved the way for future scientific discoveries. The word “gas,” which he introduced, remains a lasting testament to his contributions.

Thanks Mansur for suggesting Jan Baptist van Helmont as the next in my series of Remarkable Belgians . If anyone else has a remarkable Belgian you would like to see profiled here, just drop me a line and I will be happy to do the necessary research.

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3 thoughts on “Jan Baptist van Helmont: alchemist, physiologist, physician”

I was thinking as I was reading this that he probably put himself at risk with these radical theories. What a good thing he survived the Inquisition and was able to continue his amazing work.

It’s amazing to see how van Helmont’s work laid such crucial foundations for both chemistry and medicine as we know them today. His balanced approach—bridging alchemy and empirical science—is truly inspiring and shows how the roots of modern science often emerged from unexpected places. I especially enjoyed reading about his insights into gases and plant physiology; his experiments must have been revolutionary at the time! Thank you for bringing attention to such an important figure in scientific history. Kudos to Mansur for the suggestion!

Thanks for your insightful comment Anna. Yes it’s easy to forget how revolutionary and innovative these early scientists were.

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Fantastically Wrong: Why People Once Thought Mice Grew Out of Wheat and Sweaty Shirts

In the 17th century, physician and chemist Jean Baptiste van Helmont, apparently sick of there not being enough mice in this world, devised a home recipe for their manufacture. It was quite simple, really, far simpler than getting a girl mouse and boy mouse together with a tiny bottle of wine: “If a soiled shirt is placed in the opening of a vessel containing grains of wheat,” he wrote, “the reaction of the leaven in the shirt with fumes from the wheat will, after approximately 21 days, transform the wheat into mice.”

This, of course, may be due to mice both enjoying wheat and being capable of climbing into jars. But Helmont had another recipe for scorpions. Just get yourself a brick, carve an indentation in it, and fill it with basil. Cover that brick with another, and place in the sun. In only a few days, “fumes from the basil, acting as a leavening agent, will have transformed the vegetable matter into veritable scorpions.” Such does basil in a brick oven rise like bread … with a stinger and claws.

Helmont’s recipes were the product of some 2,000 years of fallacious thinking known as spontaneous generation. Our forebears, you see, couldn’t for the life of them figure out how maggots could just up and appear in a corpse, or how oysters just seemed to materialize in the sea. They had to have been spontaneously generating, no sex required.

The East had its own similar theories, according to Andre Brack in his book The Molecular Origins of Life . The Babylonians thought worms spontaneously erupted from canal mud, and the ancient Chinese reckoned that aphids emerged from bamboo. For the Indians, flies came from dirt and sweat.

In the West, the theory goes back to Aristotle, who put forth the first thorough writings on spontaneous generation. Some critters are lucky enough to have sex, he argued (though not in those words—I’m editorializing here), but others emerge from “putrefying earth or vegetable matter, as is the case with a number of insects.”

No, oysters are not an aphrodisiac . And they

At work here, Aristotle says, is the “vital heat” present in air . Because this air is in water and water is in earth, therefore vital heat is in everything, “so that in a sense all things are full of soul.” So in the sea, oysters spontaneously generate from the lively mud, “the earthy matter hardening round them and solidifying in the same manner as bones and horns (for these cannot be melted by fire), and the matter (or body) which contains the life being included within it.”

Aristotle’s spontaneous generation was widely accepted in Europe and the Arab world for the next two millennia. In Antony and Cleopatra , for instance, the accomplished drunkard Lepidus notes that “your Serpent of Egypt, is bred now of your mud by the operation of your Sun: so is your Crocodile.” (Though as Frederick Turner writes in Shakespeare's Twenty-First Century Economics , such drunken ramblings may have been the great writer expressing sarcastic doubt toward spontaneous generation. Regardless, the theory was alive and well.) Later on, the greatest minds of the Renaissance and Enlightenment, including Isaac Newton and René Descartes, subscribed to the theory.

Then comes along the Italian physician and naturalist Francesco Redi, who had the sneaking suspicion that maggots come from flies instead of spontaneously generating. In a series of experiments in 1668, Redi left meat to rot in closed and open flasks, and then buried still more. Of course, maggots appeared in the open flasks, but not in the closed ones or on the buried meat. Not content to stop there, he added another flask of meat but covered this one in a fine Naples veil, which allowed air flow while still keeping flies out. Maggots did indeed appear—squirming along the veil, longing to reach the meat.

Still, though, the theory of spontaneous generation would not die. And even as tiny worlds finally came into view in the 17th century with the introduction of the microscope, spontaneous generation simply adapted to the invention. In the mid-1700s, naturalist Georges-Louis Leclerc, Comte de Buffon (he seems like the type who would have gotten uppity if I didn’t use his full name, so there it is) put forth perhaps the most fanciful imagining of spontaneous generation yet.

A body, he said, is molecules organized like a mold. But after death these molecules are liberated from the body through putrefaction, then “captured by the power of some other mold.” The organic molecules are still full of life and are always active, and “rework the putrefied substance, appropriating coarser particles, reuniting them, and fashioning a multitude of small organized bodies.” Thus we get organisms like earthworms and mushrooms, he claimed.

I will posit that Louis Pasteur wore bow ties because, like me, he was inherently distrustful of regular ties, which are essentially potential nooses you wear out of the house each day, just begging to be slammed in a taxi door.

Such did spontaneous generation evolve from oysters magically emerging from mud to focus on the tiny building blocks of living things. That is, until Louis Pasteur, that master of microbes, stepped in to put it down for good. Speaking at the Sorbonne Scientific Soirée of 1864 he went after proponents of spontaneous generation . Hard .

He was responding in particular to the experiments of naturalist Félix-Archimède Pouchet, director of the Rouen Museum of Natural History, who spurned germ theory —which was all the rage at the time—in favor of spontaneous generation. Pouchet had boiled water in a flask, killing off the microbes, and added hay he'd sterilized by heating to the point of carbonization, then immediately sealed the vessel to prevent contamination. Still, his water grew muck, ostensibly demonstrating “beyond the shadow of a doubt, the existence of microscopic creatures that entered the world without germs, and thus without parents resembling themselves,” in the sardonic words of Pasteur.

Pasteur argued that airborne microbes had fallen into Pouchet’s mixture in the time it took to seal the flask after boiling it. In his own experiment, Pasteur filled two long-necked flasks with meat broth. The first he brought to a boil as-is to kill off any existing microbes. Then he heated the neck of the second and bent it so that theoretically no airborne microbes could fall in, then brought that flask to a boil as well. As he predicted, the first exploded with growth after only a few days. The second remained “completely unaltered, not just for two days, or three, or four, or even a month, a year, three years, or four!”

Just because you couldn’t see life, it turns out, doesn’t mean that it isn’t there. Speaking to the soirée’s learned scientists, Pasteur triumphantly claimed that “the doctrine of spontaneous generation will never recover from the mortal blow inflicted by this experiment.”

Indeed it didn’t. And nor did Pouchet’s reputation, really (a Britannica entry that calls your ideas “ mere curiosities ” isn’t exactly what you’d call a glowing endorsement). The germ theory he so fervently attacked has helped science save the lives of countless people, thanks in no small part to his rival’s pasteurization techniques. Let’s appreciate Pouchet, though, for his biggest contribution to science: pissing off Pasteur. We all have our purpose, I suppose.

Reference: Brack, A. (1998) The Molecular Origins of Life. Cambridge University Press