TOPIC 1 MGA TAO

384–322 B.C. — Aristotle

• Formalized the theory of spontaneous
generation, the belief that life arises from
non-living matter.
• Proposed examples such as eels from river
mud, fleas from decaying matter, and mice
from grain and rags.
• Impact: His authority made spontaneous
generation widely accepted for nearly 2,000
years, delaying acceptance of germ theory by
explaining microbes as products of decay
rather than causes of disease.

98–55 B.C. — Lucretius

• Roman poet who proposed the idea of
disease-causing “seeds” in De Rerum Natura
(On the Nature of Things).
• This was a philosophical hypothesis, not
based on experimental evidence.

1478–1553 — Girolamo Fracastoro

• In De Contagione (1546), proposed that
diseases are transmitted by invisible
“seminaria” (seeds).
• Identified three modes of transmission: direct
contact, fomites (objects), and air.
• Achievement: First systematic and coherent
theory of contagion by living agents.

1577–1652 — Francesco Stelluti

• Italian polymath and member of the
Accademia dei Lincei.
• Among the first to use the microscope for
biological studies.
• Published microscopic illustrations of bees
and weevils (1625).
• Contribution: Helped pioneer microscopy, a
key tool for the future of bacteriology.

1632–1723 — Anton van Leeuwenhoek

• First person to observe and describe
microorganisms (“animalcules”) in the 1670s.
• Studied bacteria and protozoa from pond
water, rainwater, and dental plaque.
• Sent detailed observations to the Royal
Society of London.
• Achievement: Provided the first empirical
evidence of microscopic living organisms.
Spontaneous Generation Debate

1626–1697 — Francesco Redi

• Demonstrated through controlled
experiments that maggots come from fly
eggs, not rotting meat.
• Significance: First major experimental
challenge to spontaneous generation.
• Critics argued his findings applied only to
larger organisms, not microbes.

1731–1781 — John Needham

• Boiled mutton broth, sealed it with a cork,
and observed microbial growth.
• Concluded that a “vital force” in organic
matter generated life spontaneously.
• His work supported spontaneous generation.

1729–1799 — Lazzaro Spallanzani

• Improved Needham’s experiment by boiling
broth longer and sealing flasks completely.
• No microbial growth occurred.
• Argued that microbes came from the air, not
spontaneous generation.

1821–1902 — Rudolf Virchow

• Proposed “Omnis cellula e cellula” (1855) —
every cell arises from a pre-existing cell.
• Reinforced the principle of biogenesis.
• Foundation of Cellular Pathology.

1822–1895 — Louis Pasteur

• Demonstrated that microbes exist in the air
and on surfaces.
• Proved microbes cause fermentation and
putrefaction, not the result of them.
• Definitively disproved spontaneous
generation.
• Achievement: Established biogenesis and laid
the foundation for germ theory.

1818–1865 — Ignaz Semmelweis

• In 1847, introduced handwashing with
chlorinated lime between autopsies and
childbirth.
• Dramatically reduced maternal mortality from
puerperal fever.
• Early practical application of germ theory
principles.

1827–1912 — Joseph Lister

• In 1865, introduced phenol (carbolic acid) as
a surgical disinfectant.
• Applied it to instruments, wounds, dressings,
and operating rooms.
• Achievement: Founder of antiseptic surgery.

1843–1910 — Robert Koch

• Provided definitive proof linking specific
microbes to specific diseases.
• Formulated Koch’s Postulates (1884).
• Discovered Bacillus anthracis (anthrax) and
Mycobacterium tuberculosis (tuberculosis).
• Achievement: Gave germ theory its
experimental and logical foundation.

• Buddhist monks

reportedly drank snake
venom to develop immunity against snake
bites.
• Early example of induced immunity through
controlled exposure.

17th Century — China

• Variolation practiced to prevent smallpox.
• Involved exposure to material from smallpox
lesions to induce immunity.
• One of the earliest immunization methods.

1796 — Edward Jenner

• Inoculated a person with the cowpox virus,
resulting in protection against smallpox.
• Laid the foundation for modern vaccination.

1798 — Louis Pasteur

• The first vaccine against smallpox was
discovered.
• The term “vaccination” comes from vacca,
meaning “cow”.

1910 — Paul Ehrlich

• Developed Salvarsan, a synthetic arsenicbased drug.
• First effective treatment for syphilis.
• Marked the beginning of chemotherapy.

1928 — Alexander Fleming

• Discovered the first antibiotic, penicillin.
• Revolutionized the treatment of bacterial
infections.

1930s — Sulphonamides

• Sulphonamides were synthesized.

• First widely used systemic antibacterial drugs.