Navigation


Spontaneous Generation (Sidebar 5)
spacer
Spontaneous generation (or abiogenesis) is the idea that life can arise from non-life. Until 1864, it was widely believed that at least "simple" life forms arose from the "vital forces" of non-living material. Previous to that time, it was even thought that mice came from undisturbed grain and cheese and that maggots arose from meat.

Disproving Spontaneous Generation
Among the first to perform experiments that would disqualify spontaneous generation was Francesco Redi in Italy. At this point in time, people had observed that maggots appeared in meat that was left out, and they assumed that maggots, and likely other insects, arose from non-living material. Redi showed that this was not true by putting out two dishes with meat—one covered with fine gauze, and the other uncovered. Maggots were observed in the uncovered meat and on the gauze around the other dish, but not in the covered meat. Following this demonstration, proponents of spontaneous generation said that complex organisms like insects and mice did not arise from abiogenesis, but simpler organisms could.

beaker
The Frenchman Louis Jablot, believing that microorganisms come only from other microorganisms, performed another experiment. He divided a hay infusion into two parts and heated them both to kill the microbes. One infusion was sealed and produced no growth, but the other infusion was unsealed, and quickly became infected. This experiment was repeated by others, but, unknown to them, spore forming bacteria were resistant to the heat treatment and grew in the sealed dishes. So Jablot's experiment was disregarded.

Lazzaro Spallanzani did tests similar to Jablot's, but he heated the specimen for longer periods of time. The longer heat exposure disabled even spore forming bacteria in the sample. Critics who wanted to support spontaneous generation objected that Spallanzini had damaged the "life force" of the medium, and had prevented the free oxygen flow that was necessary for spontaneous generation.

In Germany, Franz Shultze and Theodor Schwann set up an experiment to show that microbes are in the air. They heated infusions in flasks and put a glass tube in the stopper to allow airflow. They treated the mouth of the glass tube with chemicals and heat, and found no microbes in the infusions. Supporters of abiogenesis claimed that the treatment of the air had made it harmful for spontaneous generation. Schroeder and Van Dusch altered Shultze and Schwann's experiment by placing a cotton filter over the glass tube instead of treating the tube with heat and chemicals. The filter did not affect the air, but was effective in filtering out microbes.

pasteur
The decisive tests were finally performed by Louis Pasteur in 1864. Pasteur filled glass flasks with broth and curved the neck downward into a J-shape. He then heated the flasks to sterilize the broth. The J-shaped necks were not sealed, so air could enter freely, but microbes would be trapped in the curve and held by gravity. No microbes were found in the flasks of broth. To demonstrate that the broth was not harmed, he broke the neck of one, and microbes infected the broth. Some of Pasteur's original flasks are still on display at the Institute Pasteur in Paris, and are still sterile.


Previous



| Summary & Review | Practice Examination | Sitemap |

| Advanced Creationism Home | The Origin of Life Home|

Copyright © 1999 Institute for Creation Research
All Rights Reserved