Animation 4.2: Pasteur’s Experiment

INTRODUCTION

In 1862, the great French scientist Louis Pasteur tested the validity of a widely held belief in spontaneous generation. For centuries, the general population and naturalists alike believed that a variety of organisms could arise spontaneously, without being generated from similar, parental organisms.

Pasteur based his experimental design on a number of observations. He knew that bacteria grow in open containers of meat broth. He also knew that if the broth is boiled for an hour in a sealed container that remains sealed, no bacteria will grow in it. Additionally, he observed that bacteria are found in dust particles that float in the air. Armed with this information, Pasteur set up a definitive experiment to test whether microbes arise from pre-existing microbes or are generated spontaneously.

Video titled: Animation 4.2: Pasteur’s Experiment

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CONCLUSION

Pasteur's experiment showed that microbes cannot arise from nonliving materials under the conditions that existed on Earth during his lifetime. But his experiment did not prove that spontaneous generation never occurred. Eons ago, conditions on Earth and in the atmosphere above it were vastly different. Indeed, conditions similar to those found on primitive Earth may have existed, or may exist now, on other bodies in our solar system and elsewhere. This has led scientists to ask whether life has originated on other bodies in space, as it did on Earth.

Textbook Reference: Key Concept 4.2 The Small Molecules of Life Originated on Primitive Earth

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