Theories of Biologists

What were Aristotles contributions?

• Proposed the idea of Spontaneous Generation also known as Abiogenesis.

What is Spontaneous Generation / Abiogenesis?

• It is the idea that living things can arise from non-living matter.

Who is Francesco Redi and what were his contributions?

• Italian Physician

• Experimented with Jars containing Meat.

  • Jars: One Open, One Sealed, One Gauze / Covered in Net.

• This experiment was to observe which jars would develop maggots, and the results disproved the idea of spontaneous generation.

• Open Jar - Maggots on the Meat

• Sealed - No Maggots on the Meat

• Gauze - Maggots only on the Gauze

What were Louis Pasteurs contributions?

• Experimented with S-Flasks containing broth to prove microbes only come from microbes.

  • Step 1: S-Shaped Flasks filled with Broth.

  • Step 2: Flasks were boiled, microbes killed.

  • Step 3: Flasks at different locations, dust only in the neck of the flask. ( Did not turn cloudy, therefore no microbes found )

• The S-Shaped flasks let air in but kept microbes out. Therefore disproved spontaneous generation.

Who is Robert Hooke and what were his contributions?

• English scientist

• Made an improved microscope to observe thin slices of cork. Named what he saw as cells.

Who is Matthias Schleiden & Theodore Schwann, and what were their contributions?

• Schledien: Botanist ( studying plants )

• Shwann: Zoologist ( studying animals )

• Together they stated that “All living things are made up of Cells.” Therefore contributing to the Cell Theory with Rudolf Virchow.

What were Rudolf Virchows contributions?

• Contribution to the Cell Theory with Matthias Schleiden and Theodore Schwann.

• Stated that “Cells only arise from pre-existing Cells,” disproving the idea of Spontaneous Generation.