Redi’s Experiment
Redi took four bottles. He put a dead snake in one
bottle, a few dead fish in second bottle, dead eel in third bottle and a piece
of meat in the fourth bottle. All these bottles were left open. The flies could
enter these bottles. Then he took four more such bottles. He put some dead
animals in all four bottles but covered the mouth of bottles.
(Figure from book)
After few days, maggots were produced in four open bottles. Maggots were not
produced in closed bottles. Moreover, no flies were seen. Therefore, it was
proved that maggots were not produced spontaneously by produced due to flied
which were visiting the open bottles. The maggots were the larvae produced from
the eggs of the visiting flies.
Needham’s Experiment
In 1948, an English scientist Needham boiled the
meat in the water and prepared gravy. He poured this gravy into the bottles and
closes their mouth with corks. After some days, many microscopic organisms were
produced. In this way, the believers of abiogenesis were once again gain
courage.
(Figure from book)
Experiment of Spallanzani
In 1767, an Italian scientists Spallanzani
criticized the experiment of Needham. He said that air entered the bottles
through the pores of cork and hence living organisms were produced.
(Figure from Book)
Spallanzani put the boiled meat and vegetables in clean bottles and then sealed
the mouth of bottles by heat. He placed these sealed bottles in boiled water to
kill the possible germs. After some days, he found no organisms. He left the
same boiled meat and vegetables in open bottles at the same time. Some living
organisms were produced in these bottles. This supportd the concept of
Biogenesis. But the believers of A biogenesis said that air removed by
Spallanzani was necessary for living things so no organisms were produced in
sealed bottles. When oxygen was discovered the supporters of A biogenesis said
that Spallanzani had removed oxygen where by no life could be
produced in his experiment.
Experiment of Louis Pasteur
The argument on Biogenesis and Abiogenesis
continued up to the middle of, 19th century. A well-known French scientist,
Louis Pasteur proved, after simple but very careful experiments, that
abiogenesis could not occur in present environment of earth. He proved that
living organisms could only be produced from their parents.
In 1864, Pasteur performed his experiment in front of the commission formed to
solve the issue. He took flasks, which had long curved S-shaped necks. He
placed fermentable infusion (Yeast + sugar + water) in flasks and left their
mouth open.
(Figure from Book)
He boiled the yeast infusion in the flasks. After this, he allowed to cool them
and kept them as such. He observed that no life ws produced even after the
lapse of several days, because microscopic organisms entering along with air
got stuck up in on the curved walls of the glass necks. Then he broke up the
curved necks, so that air containing microscopic organisms could reach the
infusion. Now he noted that microscopic organisms were produced within 48
hours. This proved that if care was taken and no microscopic organisms and
reproductive structures (eggs or spores) approach the infusion, no life could
be produced because thee is no spontaneous generation of life from non life. After
Pasteur, no further experiments were performed on origin of life for the next
60 years. In 1920, a Russian biochemist Alexander Oparin and a British
biologist J.B.S 1-Ialdane suggested that life on earth was originated after a
long and gradual molecular evolution and there was no spontaneous and
miraculous origin of life on earth.
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