Are Seeds Alive?
There had been a controversy between two theories: biogenesis and abiogenesis.
Abiogenesis is the theory that life come about from non-life, and biogenesis is the theory of a living can only come from a living.
Francesco Redi had seemed to prove abiogenesis in 1668. With his experiment he thought maggots arose from fly eggs; but to test his hypothesis he put meat in different flasks. Some were open to the air, some sealed completely, and others covered with gauze. And of course as he expected, maggots did appear only in the flask in which the flies could reach. But spontaneous generation still survived as a theory, even Redi still believed abiogenesis occurred under some situations.
But in 1745, John Needham proposed that everyone knew that boiling the broth would kill microorganisms. So he tested to see if it would appear spontaneously after boiling the meat broth then sealed the flask; microorganisms appeared.
After Needham’s theory, Lazzaro Spallnzani was not convinced, so he suggested that the microorganisms had entered the broth from the air after the broth was boiled, but before it was sealed. To test it he modified Needham’s experiment. He placed the chicken broth in a sealed flask and removed the air, and then he started to boil the broth. No microorganisms appeared. So he proved that spontaneous generation could not occur without air.
Louis Pasteur responded to a competition for the best experiment to prove or disprove spontaneous generation. In Pasteur’s experiment he boiled meat broth in a flask, heated the neck of the flask in a flame until it became flexible, and bent it into an S-shape. Air was able to enter the flask but airborne microorganisms could not and they would settle in the neck due to gravity, and of course as he expected nothing grew. Then in the later experiment he tilted the flask so the broth reached the low