THE BEGINNING
Microscopy
Discovery
Science

DISCOVERIES
Abiogenesis
Virulence
Vaccines

REVENGE
Antibiotics
Clean Revolution
Resistance

AGE OF DISCOVERY

Robert Hooke's and Antony van Leeuwenhoek's observations sparked a new era of discovery in microbiology. Spontaneous generation (abiogenesis), a long-held theory that life springs up from non-living or decaying organic matter, was based on observations of rotting food seemingly producing living organisms. Francesco Redi, a respected philosopher at the court of the Medici Grand Duke in Tuscany, was the first scientist to question the idea of spontaneous generation. By setting up a simple experiment in which decaying meat was placed in three jars, one uncovered, one sealed, and one covered by mesh, allowing air to circulate, he demonstrated that only the open jar which flies could access produced maggots. Thus, decaying meat does not spontaneously produce maggots. Partially due to the simplicity of Redi's experiment (anyone could reproduce it), people began to doubt spontaneous generation.

In the 1700s, John Needham, a English clergyman proposed that abiogenesis occurred due to the random "clumping
of organic molecules." Spontaneous generation gained momentum during the late 18th and 19th centuries when further advances in microscopy allowed people to view bacteria and other microorganisms. It was not until Louis Pasteur's experiments in 1859 that the idea of spontaneous generation began to wane. The famous swan-necked flask experiment succeeded where others failed in demonstrating that life could not spontaneously arise from non-living matter even when air was present. Subsequent experiments by other scientists led to further confusion when boiled broth was found to be clouded by growth (turbidity). It was not until 1876 that these concerns were finally put to rest with the discovery of heat-resistant endospores.

Probably the most famous contribution to microbiology by Pasteur is the heating process he developed to kill spoilage microbes while still preserving flavour. Pasteurization is credited with saving thousands of lives. Pasteur also made notable contributions in the field of vaccination and immunity. Studying cholera, Pasteur found that attenuated organisms, inoculated into poultry, offered protection against virulent strains. Based on this research, he developed the first rabies and anthrax vaccines.

Though Pasteur's achievements in microbial immunity were revolutionary, Edward Jenner is credited with inventing the first vaccine against smallpox in the late 1700s. In 1796, Jenner, a British physician, developed a controversial experiment to determine the validity of rumours that were circulating in rural communities. Milkmaids and villagers often recanted, "if you want to marry a woman who will never be scarred by the pox, marry a milkmaid." Jenner speculated that becoming infected with cowpox could offer protection against the more virulent smallpox. To test his hypothesis, he created an inoculation with scrapings of cowpox lesions from the fingers of Sarah Nelmes, a young milkmaid and injected it into an 8-year-old boy named James Phipps. As expected, James developed the mild fever and cowpox lesions typical of the disease. After a few weeks of recovery, Jenner injected James with the live smallpox virus and found that the boy was indeed protected from the disease. In 1798, Jenner published his findings and presented them to the Royal Society.

Francesco Redi
17th century Italian
philosopher

Louis Pasteur
led a new age of
 scientific discovery in
the 19th century

James Phipps
Edward Jenner tests his
hypothesis and develops
the first smallpox vaccine

Cowpox
Edward Jenner's drawing
of Sarah Nelme's hand

< Previous Page

Next Page