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Jansen lived from 1570 to 1638. He invented the compound microscope in 1590. This allowed people to see cells.
https://www.britannica.com/biography/Zacharias-Jansen

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Leeuwenhoek lived from 1632 to 1723. He is known as the "father of microbiology". He was the first person to observe and describe microorganisms.
https://makingscience.royalsociety.org/s/rs/people/fst00039851

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Robert Hooke lived from 1635 to 1703. He coined the word 'cell'. He was able to realize that fossils are the remains of living things.
https://www.biography.com/scholar/robert-hooke

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Who Was Robert Hooke?

Scientist Robert Hooke was educated at Oxford and spent his career at the Royal Society and Gresham College. His research and experiments ranged from astronomy to biology to physics; he is particularly recognized for the observations he made while using a microscope and for "Hooke's Law" of elasticity. Hooke died in London in 1703.

Early Life and Education

Robert Hooke was born in the town of Freshwater, on England's Isle of Wight, on July 18, 1635. His parents were John Hooke, who served as curate for the local church parish, and Cecily (née Gyles) Hooke.

Initially a sickly child, Hooke grew to be a quick learner who was interested in painting and adept at making mechanical toys and models. After his father's death in 1648, the 13-year-old Hooke was sent to London to apprentice with painter Peter Lely. This connection turned out to be a short one, and he went instead to study at London's Westminster School.

In 1653, Hooke enrolled at Oxford's Christ Church College, where he supplemented his meager funds by working as an assistant to the scientist Robert Boyle. While studying subjects ranging from astronomy to chemistry, Hooke also made influential friends, such as future architect Christopher Wren.

Teaching, Research and Other Occupations

Hooke was appointed curator of experiments for the newly formed Royal Society of London in 1662, a position he obtained with Boyle's support. Hooke became a fellow of the society in 1663.

Unlike many of the gentleman scientists he interacted with, Hooke required an income. In 1665, he accepted a position as professor of geometry at Gresham College in London. After the "Great Fire" destroyed much of London in 1666, Hooke became a city surveyor. Working with Wren, he assessed the damage and redesigned many of London's streets and public buildings.

Major Discoveries and Achievements

A true polymath, the topics Hooke covered during his career include comets, the motion of light, the rotation of Jupiter, gravity, human memory and the properties of air. In all of his studies and demonstrations, he adhered to the scientific method of experimentation and observation. Hooke also utilized the most up-to-date instruments in his many projects.

Hooke's most important publication was Micrographia, a 1665 volume documenting experiments he had made with a microscope. In this groundbreaking study, he coined the term "cell" while discussing the structure of cork. He also described flies, feathers and snowflakes, and correctly identified fossils as remnants of once-living things.

The 1678 publication of Hooke's Lectures of Spring shared his theory of elasticity; in what came to be known as "Hooke's Law," he stated that the force required to extend or compress a spring is proportional to the distance of that extension or compression. In an ongoing, related project, Hooke worked for many years on the invention of a spring-regulated watch.

Personal Life and Death

Hooke never married. His niece, Grace Hooke, his longtime live-in companion and housekeeper, as well as his eventual lover, died in 1687; Hooke was inconsolable at the loss.

Hooke's career was marred by arguments with other prominent scientists. He often sparred with fellow Englishman Isaac Newton, including one 1686 dispute over Hooke's possible influence on Newton's famous book Principia Mathematica.

In his last year of life, Hooke suffered from symptoms that may have been caused by diabetes. He died at the age of 67 in London on March 3, 1703.

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Scientist Robert Hooke was educated at Oxford and spent his career at the Royal Society and Gresham College. His research and experiments ranged from astronomy to biology to physics; he is particularly recognized for the observations he made while using a microscope and for "Hooke's Law" of elasticity.

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Schleiden lived from 1804 to 1881. He helped to develop the cell theory in the 19th century. He used microscopes in his research and encouraged the development of new ones.
https://embryo.asu.edu/pages/matthias-jacob-schleiden-1804-1881

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Schwann lived from 1810 to 1882. He defined the cell as the "basic unit of animal structure". He coined the word 'metabolism'.
https://www.britannica.com/biography/Theodor-Schwann

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This article was most recently revised and updated by

Theodor Schwann, (born December 7, 1810, Neuss, Prussia [Germany]-died January 11, 1882, Cologne, Germany), German physiologist who founded modern histology by defining the cell as the basic unit of animal structure.

Schwann studied at the Jesuits' College at Cologne before attending the University of Bonn and then the University of Würzburg, where he began his medical studies. In 1834, after graduating with a medical degree from the University of Berlin, Schwann assisted renowned physiologist Johannes Peter Müller. In 1836, while investigating digestive processes, he isolated a substance responsible for digestion in the stomach and named it pepsin, the first enzyme prepared from animal tissue. In 1839 Schwann took an appointment as professor of anatomy at the Catholic University of Leuven (Louvain) in Belgium. That same year his seminal work, Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants, was published. In it he extended to animals the cell theory that had been developed the year before for plants by German botanist Matthias Jacob Schleiden, who was working at the University of Jena and who Schwann knew well. At Leuven Schwann observed the formation of yeast spores and concluded that the fermentation of sugar and starch was the result of life processes. In this way, Schwann was one of the first to contribute to the germ theory of alcoholic fermentation, later elucidated by French chemist and microbiologist Louis Pasteur.

In 1848 Schwann accepted a professorship at the University of Liège, where he stayed for the remainder of his career. At Liège he investigated muscular contraction and nerve structure, discovering the striated muscle in the upper esophagus and the myelin sheath covering peripheral axons, now known as Schwann cells. He coined the term metabolism for the chemical changes that take place in living tissue, identified the role played by microorganisms in putrefaction, and formulated the basic principles of embryology by observing that the egg is a single cell that eventually develops into a complete organism. His later years were marked by increasing concern with theological issues.

The Editors of Encyclopaedia Britannica Adam Augustyn, Managing Editor, Reference Content.

Learn More in these related Britannica articles:

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Theodor Schwann | Biography, Education, Discoveries, & Facts

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Theodor Schwann, German physiologist who founded modern histology by defining the cell as the basic unit of animal structure. He also coined the term 'metabolism' for the chemical changes that take place in living tissue and formulated the basic principles of embryology.

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Virchow lived from 1821 to 1902. He discovered the cause of disease to be malfunctioning cells. He carried out the first autopsies involving microscopic examination.
https://www.famousscientists.org/rudolf-virchow/

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Lived 1821 - 1902.
Rudolf Virchow was an eminent pathologist and politician, widely regarded as one of the greatest and most influential physicians in history. A founding father of both pathology and social medicine, Virchow analyzed the effects of disease in various organs and tissues of the human body. He correctly identified that diseases are caused by malfunctioning cells.

A man of boundless energy, he simultaneously had four careers: medical scientist, editor of several medical journals, politician, and anthropologist. Although he played a tremendous part in ridding medicine of unscientific practices, he also made some rather large scientific errors.

Beginnings

Rudolf Ludwig Carl Virchow was born on October 13, 1821 in the town of Schivelbein, in the German Kingdom of Prussia. Today the town is called &Sacute;widwin and lies in Poland.

His father was Carl Christian Siegfried Virchow, a farmer, and town treasurer of Schivelbein; his mother was Johanna Maria Hesse. The couple were not especially well-off financially and Rudolf was their only child. His parents loved the natural world and passed this love on to their son, taking him on bird watching trips.

Rudolf attended elementary school in Schivelbein. From his earliest days at school, he seems to have been exceptionally gifted intellectually, so much so that his parents paid for extra lessons to push him forward. From elementary school he progressed to the Gymnasium (a high school for academically strong students) in Köslin, about 40 miles from his hometown.

Rudolf's high school curriculum was classical, with heavy emphasis on Greek and Latin. This was not a problem for Rudolf, who had a passion and remarkable ability for learning languages. In addition to Greek and Latin, he also learned Dutch, English, French and Hebrew. In his spare time between high school and medical school he taught himself Italian.

He graduated from high school in 1839, aged 17.

Abandoning his original idea of becoming a pastor - he didn't think his voice was strong enough to be an effective preacher - he was awarded a scholarship to study medicine at the Friedrich-Wilhelms University in Prussia's capital city, Berlin. Completing his course in 1843, he then spent short amounts of time in a number of different medical jobs.

His passion was pathology - the study of diseases.

Politics in Brief
A man with incredible energy levels, Virchow reveled in an important political career in addition to his scientific career. Here we'll be concerned mainly with the science. Suffice to say that Virchow's politics were liberal. He promoted better education, better living conditions, and better health for the poor. These political beliefs coincided with his ideas for social medicine.

Virchow was elected to the German Parliament in 1880 to represent the party he helped found, the German Progress Party. He had a sharp-tongue, and his political opponents became wary of his sarcasm. Virchow was ardently anti-Catholic, believing the Catholic Church's influence led to bad outcomes for society and the poor.

Rudolf Virchow's Contributions to Science and Pathology

Autopsies and Leukemia

Virchow carried out the first systematic autopsies involving microscopic examination of tissue. One such autopsy in 1845 led to his first published contribution to science.

Virchow identified and named the disease leukemia and offered the best description of it available. He named the disease by combining the Greek words leukos (white) and aima (blood). Even in his earliest work he focused heavily on cells.

Outflanking the journals that blocked publication of his work

In 1847 Virchow started a new job, teaching pathological anatomy at the University of Berlin. Although he had once believed his voice too weak to preach, he had now become a supremely self-assured teacher and researcher.

He was also ambitious, and had grown increasingly frustrated by the editors of German medical journals. They refused to publish some of his research papers, and, in Virchow's opinion, were hamstrung by out-of-date ideas about medicine.

In his new teaching job he met Benno Reinhardt, another young physician who shared his dim view of the medical journals. Virchow and Reinhardt decided to bypass the journals' stuffy editors entirely.

They launched their own journal, Archive for Pathological Anatomy and Physiology and Clinical Medicine. This new journal insisted all medical contributions should be based on robust, well-researched science. Virchow utterly rejected medical practices that had persisted for millennia, which he believed lacked a scientific basis, such as Galen's use of the 'humours.'

Virchow and Reinhardt's journal has proven to be remarkably resilient. Today it is still one of the leading medical journals. It is now called Virchows Archiv. Sadly its founding co-editor Benno Reinhardt died young in 1852. Virchow, who had a prodigious appetite for hard work, became the journal's sole editor until his own death in 1902.

Epidemics and Public Health

Early in 1848 Virchow was sent by the Prussian Government to Upper Silesia to investigate the typhus epidemic that had begun the previous year and was claiming thousands of lives.

After studying the situation, Virchow characterized the peasants of Upper Silesia as lazy and unhygienic. He was shocked at the extreme poverty they lived in and their extremely poor diet. He blamed their plight on the combined effects of the Catholic Church sapping the people of ambition and local landowners removing any wealth generated in Upper Silesia to be spent elsewhere.

"Wealth, education and liberty depend on one another and thus, conversely, do hunger, ignorance and servitude."

The medical consensus at the time, accepted by Virchow, was that diseases like typhus are caused by 'miasma' - bad air caused by rotting matter. Virchow believed malaria was caused by rotting vegetable miasma, while typhus was caused by rotting animal miasma. So, although he rejected some doctrines of medicine taught in ancient times by Galen, he did not question the truth of miasmas.

Virchow did not recognize that epidemics are spread by microorganisms.

He formed the view that the main cause of the epidemic in Upper Silesia was the terrible conditions most of the people were living in. He decided that if living conditions could be improved, there would be no more epidemics.

Epidemics, he said, were best treated politically rather than medically. This is not entirely correct. However, he was correct to say that improving people's living conditions, hygiene, and diet would be highly beneficial to their general health and well-being. And, although he did not know it, better hygiene slows the spread of the microorganisms that cause epidemics such as typhus, and, more recently, Ebola, bird flu, and SARS.

The Beginning of Social Medicine

Never slow to act on his beliefs, in July 1848 Virchow founded the weekly magazine Medical Reform to promote his new concept of social medicine and his idea that:

"physicians are the natural advocates of the poor".

The magazine ran for about a year before folding, but in that time it was highly influential in promoting improved public health for everyone in Germany, including the poorest.

How do Cells Form?

In 1849 Virchow moved to University of Würzburg and began a program of serious research into the roles cells play in the body and in disease.

The great Theodor Schwann had pushed biological science forward dramatically in 1837, when he established that all animal tissues are made of cells.

However, Schwann made a major error when he said that new cells are created from a fluid called blastema. Although incorrect, this was the accepted explanation for cell reproduction in the early 1850s.

Scientists also believed that imbalances in the body created blastema in which disease cells were created. This belief began changing in 1855 when Virchow, aged 34, published an essay in which, famously, he declared:

"Every cell arises from another cell."

Although he was not the first to suggest this, people only began to take serious notice after Virchow said it. It was a turning point in biology.

Cellular Pathology

In 1856 Virchow returned to Berlin to the Chair of Pathological Anatomy at the Friedrich-Wilhelms University.

In 1858 he published Cellular Pathology, a groundbreaking book of 20 lectures he had given at the university, which laid the foundations of modern pathology and indeed of modern medical theory.

Simply put, Virchow established that all diseases can be traced to cells. Diseases attack normal cells and cause them to malfunction. A whole organism does not get sick; each disease affects a particular set or sets of an organism's cells, not all of its cells. Different diseases affect different types of cell.

Virchow told doctors and pathologists seeking to diagnose diseases or to understand their effects that they could do this best by studying the cells that are affected.

"Virchow, the chief founder of modern scientific medicine ... will rank for all mankind and for all time to come as one of the greatest figures in science ... the establishment by Virchow of the principles of cellular pathology marked the greatest advance which scientific medicine had made since its beginning."

Trichinosis, Meat Inspection, and the Sausage Dual

Trichinosis
Trichinosis is a disease caused by Trichinella roundworm parasites. At its worst, the disease is fatal. In 1859-60, Virchow discovered and described fully the life cycle of Trichinella spiralis in pigs and showed how the worms came to infect humans, causing the disease. He told people they had to cook pork well to avoid infection.

Meat Inspection
Virchow showed how the larvae of Trichinella could be seen in raw meat using low-powered microscopes. He called for and, in Berlin, got meat inspections in abattoirs as a public health measure. Meat inspections, carried out by vets, then spread slowly through Prussia, Germany, and internationally.

The Sausage Duel
In parliament, when Virchow fiercely opposed Otto von Bismarck's increase in military spending in 1865, Bismarck challenged him to a duel. Germany's Minister for War was to be one of Bismarck's seconds and he turned up at Virchow's house. Sensibly Virchow turned down the challenge. (Unlike the brilliant mathematician Evariste Galois, who was killed in a duel.)

At the time, Bismarck's challenge to Virchow was something of a media sensation. Sometimes today readers will find that this duel is fictionalized as the sausage duel. In brief, the tale says that after Bismarck issued the challenge, Virchow accepted, and since he had been challenged, he had the choice of weapons. He chose pork sausages, a cooked one for himself and a raw one for Bismarck. The raw sausage would inevitably have infected Bismarck with Trichinella. Bismarck then withdrew from the duel.

How Does Cancer Start?

Virchow was tremendously far-sighted in his view of cancers. He wrote, correctly, that one important cause of cancer was inflammation caused by white blood cells.

Unfortunately, he got the overall mechanism wrong, claiming the inflammation and so the cancer were spread by a liquid. In fact, cancer is spread by diseased cells, as established by Karl Thiersch in the 1860s.

Sadly, and no doubt at the cost of millions of lives, Virchow's correct claim that many cancers are initiated by inflammation was ignored for a long time.

A Huge Number of Major Discoveries

Virchow made a huge number of discoveries and contributions to medical science - too many to document in this simple article.

He published over 2000 scientific papers and books, and powerfully influenced medical practice, medical theory, and public health practices in Germany and the world.

He named and was the first to catalog conditions such as embolism, thrombosis, chordoma, and ochronosis.

Virchow's node is named in his honor, following his discovery that an enlarged left supraclavicular node is a very early sign of stomach or lung cancer.

In addition to his work in medical science, he carried out an enormous amount of research looking at human ethnology and anthropology.

Virchow's Greatest Errors

Evolution by Natural Selection

In 1858, Darwin and Wallace's theory of evolution by natural selection was unleashed on an unsuspecting world.

In its early years the theory was highly controversial and was fiercely debated.

Virchow opposed the theory from the beginning and never relented in his opposition.

In fact, in 1877, he said the idea that man had descended from apes was an attack on society's moral foundations. He voiced his opinion that teaching the theory of evolution should not be permitted in Germany's public schools.

Virchow also dismissed the first Neanderthal specimens, claiming they were modern Homo sapiens with deformations caused by rickets and arthritis. In the mid-1860s Virchow was the most important medical man in Germany, and his opposition significantly delayed the scientific acceptance of Neanderthal humans, particularly in Germany.

The Germ Theory of Disease

The germ theory of disease had been around for many centuries, but was not taken seriously by most scientists until Louis Pasteur started advancing it, backed with experimental data, in the late 1850s.

Virchow opposed the germ theory of disease.

His own belief was that cells became diseased as a result of internal processes resulting from imbalances in the body. In fact, Virchow was partly correct: imbalances in the body can lead to cells malfunctioning and becoming diseased.

However, cells can also become diseased when they are attacked by microorganisms. Virchow was wrong to oppose the germ theory.

Opposition to Hand Washing

Ignaz Semmelweis was the doctor in charge of a birthing ward in Vienna, Austria. In 1847 he showed that if medical staff washed their hands before examining patients, death rates dropped dramatically.

Many scientists, including Virchow, dismissed Semmelweis's work as rubbish. Semmelweis died in tragic circumstances in 1865 following the ongoing unreasonable rejection of his work by other scientists.

A very large number of unnecessary deaths were caused by the dismissal of Semmelweis's work.

The Greatest Prize in Science

In 1892 Virchow was awarded the British Royal Society's Copley Medal, then the greatest prize in science. The award was made:

"For his investigations in pathology, pathological anatomy, and prehistoric archaeology."

Previous recipients included Benjamin Franklin, Alessandro Volta, Michael Faraday, Robert Bunsen, Charles Darwin, and Louis Pasteur.

Some Personal Details and the End

Virchow married Rose Mayer in 1850. They had six children: Karl, who became a chemist; Hans, who became an anatomist; Adele; Ernst; Marie; and Hanna Elisabeth.

Apart from Karl, who died aged 61, the Virchow children enjoyed rather long lives - particularly for the era they were alive in - living to be 87, 99, 84, 85 and 90 years old respectively.

Rudolph Virchow died from heart failure at the age of 80 in Berlin on September 5, 1902. He had fractured his thigh falling from a tramcar in January of that year. Although at first he seemed to be recovering, he gradually fell deeper into ill-health. He was buried in the Old St.-Matthäus Churchyard in Schöneberg, Berlin. Rose was buried beside him following her death in 1913.

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Further Reading
Karl Blind
Personal Recollections of Virchow
The North American Review, Vol. 175, No. 552, p613-624, Nov., 1902

Arthur E. Boak
Rudolf Virchow - Anthropologist and Archeologist
The Scientific Monthly, 13, p40-45, 1921

Alexander Vucinich
Darwin in Russian Thought
University of California Press, 1988

L. Z. Saunders
Virchow's Contributions to Veterinary Medicine: Celebrated Then, Forgotten Now
Veterinary Pathology, vol. 37 no. 3 p199-207, May 2000

Paulo Scarani
Rudolf Virchow (1821 - 1902)
Virchows Arch, 442, p95-98, 2003

Brian L. D. Coghlan, Leon P. Bignold
Virchow's Eulogies: Rudolf Virchow in Tribute to his Fellow Scientists
Springer Science & Business Media, 2008

Michael Titford
Rudolf Virchow: Cellular Pathologist
LabMedicine, 41, p311-312, 2010

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Lived 1821 - 1902. Rudolf Virchow was an eminent pathologist and politician, widely regarded as one of the greatest and most influential physicians in history. A founding father of both pathology and social medicine, Virchow analyzed the effects of disease in various organs and tissues of the human body.

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Pasteur lived from 1822 to 1895. He discovered molecular asymmetry. He was convinced that asymmetry was a necessary part of life.
https://www.britannica.com/biography/Louis-Pasteur/Research-career

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In 1843 Pasteur was admitted to the École Normale Supérieure (a teachers' college in Paris), where he attended lectures by French chemist Jean-Baptiste-André Dumas and became Dumas's teaching assistant. Pasteur obtained his master of science degree in 1845 and then acquired an advanced degree in physical sciences. He later earned his doctorate in sciences in 1847. Pasteur was appointed professor of physics at the Dijon Lycée (secondary school) in 1848 but shortly thereafter accepted a position as professor of chemistry at the University of Strasbourg. On May 29, 1849, he married Marie Laurent, the daughter of the rector of the university. The couple had five children; however, only two survived childhood.

Molecular asymmetry

Soon after graduating from the École Normale Supérieure, Pasteur became puzzled by the discovery of the German chemist Eilhardt Mitscherlich, who had shown that tartrates and paratartrates behaved differently toward polarized light: tartrates rotated the plane of polarized light, whereas paratartrates did not. This was unusual because the compounds displayed identical chemical properties. Pasteur noted that the tartrate crystals exhibited asymmetric forms that corresponded to their optical asymmetry. He made the surprising observation that crystalline paratartrate consisted of a mixture of crystals in a right-handed configuration. However, when these crystals were separated manually, he found that they exhibited right and left asymmetry. In other words, a balanced mixture of both right and left crystals was optically inactive. Thus, Pasteur discovered the existence of molecular asymmetry, the foundation of stereochemistry, as it was revealed by optical activity. Over the course of the next 10 years, Pasteur further investigated the ability of organic substances to rotate the plane of polarized light. He also studied the relationship that existed between crystal structure and molecular configuration. His studies convinced him that asymmetry was one of the fundamental characteristics of living matter.

Germ theory of fermentation

In 1854 Pasteur was appointed professor of chemistry and dean of the science faculty at the University of Lille. While working at Lille, he was asked to help solve problems related to alcohol production at a local distillery, and thus he began a series of studies on alcoholic fermentation. His work on these problems led to his involvement in tackling a variety of other practical and economic problems involving fermentation. His efforts proved successful in unraveling most of these problems, and new theoretical implications emerged from his work. Pasteur investigated a broad range of aspects of fermentation, including the production of compounds such as lactic acid that are responsible for the souring of milk. He also studied butyric acid fermentation.

In 1857 Pasteur left Lille and returned to Paris, having been appointed manager and director of scientific studies at the École Normale Supérieure. That same year he presented experimental evidence for the participation of living organisms in all fermentative processes and showed that a specific organism was associated with each particular fermentation. This evidence gave rise to the germ theory of fermentation.

Pasteur effect

The realization that specific organisms were involved in fermentation was further supported by Pasteur's studies of butyric acid fermentation. These studies led Pasteur to the unexpected discovery that the fermentation process could be arrested by passing air (that is, oxygen) through the fermenting fluid, a process known today as the Pasteur effect. He concluded that this was due to the presence of a life-form that could function only in the absence of oxygen. This led to his introduction of the terms aerobic and anaerobic to designate organisms that live in the presence or absence of oxygen, respectively. He further proposed that the phenomena occurring during putrefaction were due to specific germs that function under anaerobic conditions.

Pasteur readily applied his knowledge of microbes and fermentation to the wine and beer industries in France, effectively saving the industries from collapse due to problems associated with production and with contamination that occurred during export. In 1863, at the request of the emperor of France, Napoleon III, Pasteur studied wine contamination and showed it to be caused by microbes. To prevent contamination, Pasteur used a simple procedure: he heated the wine to 50-60 °C (120-140 °F), a process now known universally as pasteurization. Today pasteurization is seldom used for wines that benefit from aging, since it kills the organisms that contribute to the aging process, but it is applied to many foods and beverages, particularly milk.

Following Pasteur's success with wine, he focused his studies on beer. By developing practical techniques for the control of beer fermentation, he was able to provide a rational methodology for the brewing industry. He also devised a method for the manufacturing of beer that prevented deterioration of the product during long periods of transport on ships.

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Louis Pasteur - Louis Pasteur - Research career: In 1843 Pasteur was admitted to the École Normale Supérieure (a teachers' college in Paris), where he attended lectures by French chemist Jean-Baptiste-André Dumas and became Dumas's teaching assistant. Pasteur obtained his master of science degree in 1845 and then acquired an advanced degree in physical sciences.

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1. How did Janssen's, Hooke's, and Leewenhoek's work contribute to the work of the scientists that came after them?
It provided a foundation for the development of cell theory.
2. How would our lives be different if we had never realized the existence of microorganisms? Provide at least one example to support your answer.
We wouldn't be able to understand bacteria so we wouldn't understand disease.
3. Describe the concept of spontaneous generation. Why do you think it took such a long time for people to accept that this idea was incorrect?
The concept of spontaneous generation suggests that some organisms appear out of various things. It took so long to prove false because people didn't understand that all existing cells are produced by other cells, so the organisms couldn't appear out of nowhere.
4. How do you think the cell theory impacted later scientific discoveries? Explain your answer.
Cell theory likely impacted later scientific discoveries because it progressed development of microscopes and other technology.
5. The microscope and numerous experiments lead to the rejection of spontaneous generation. This idea had been accepted by most people, including scientists, for over 200 years. How does this demonstrate the true nature of science?
The true nature of science is that theories can change, so the idea of spontaneous generation was overthrown by a theory with more evidence.