2. What is Biogenesis? Biogenesis is the principle which sates that all living things come from other living things. Before Biogenesis people believed that things came from non-living things. This was known was spontaneous generation.

3. Francesco Redi During 1626-1697, there lived an Italian Scientist by the name of Francesco Redi who questioned the idea of spontaneous generation of maggots in rotting meat.

4. Redi’s Experiment To test whether or not flies spontaneously appeared from rotting meat he decided set up an experiment. Redi placed 2 pieces of meet in separate jars. He sealed on jar off to be his experimental subject and the other was left open to be the control group.

5. The Microscope Although Redi’s experiment brought up many questions about spontaneous generation. The new invention of the microscope caused people to begin a belief of “vital force”

6. Vital Force? People during the time believed that there was a “Vital force” in the air that caused microorganisms appear

7. Lazzaro Spallanzani Lazzaro Spallanzani, also an Italian scientist, designed an experiment to disprove the theory of this “Vital Force”. He personally believed that Microorganisms did not come from the vital force but came from other microorganisms

8. Spallanzani’s Experiment To prove his point, Spallanzani set up an experiment to prove that vital force was a myth. Spallanzani set up 2 flasks full of broth. He heated both up till they boiled and sealed only one.

9. Conclusion? Spallanzani’s conclusion was that the broth only became spoiled when it came in contact with other microorganisms. However, his conclusion was disregarded. Other scientists at the time believed that his experiment was flawed. They argued that Spallanzani had heated the flask too long. Destroying the vital force inside.

10. Louis Pasteur Many years had passed and the mystery of whether or not spontaneous generation existed was still debated A French scientist in named Louis Pasteur made things clear

11. Pasteur’s Curved Neck Flask To make argument impossible, Pasteur decided to fill a flask with broth and boil it. This flask was unique however, it had a curved neck which allowed air inside the flask to make contact with the air outside. The flask’s curved neck however did not allow solid particles such as microorganisms to enter.

12. The End Pasteur’s experiment ended in a success. The curved necked flasks stayed clear for about a year. However when the neck on the flask was broken, the broth inside the flask would become cloudy in about 1 to 2 days. Pasteur’s experiment put an end to the belief of spontaneous generation.