|
THE HYPOTHESIS OF THE SPONTANEOUS GENERATION IS STILL UNDER DISCUSSION...
- The English naturalist Buffon (1707-1788)
continued to support the idea that a lot of animals (such
as winged bugs,
worms, aphides...) were born spontaneously, without parents.
He tought that every animal was made by indestructible
and immortal particles and that, when it died,
these particles became free and spontaneously
put themselves together
again
in
order to form new living beings.
- The French scientist Rčamur (1683-1757),
according with Redi, wrote: "…although
it is ridicule to think that bees beetles develop from putrid meat of a year-old calf or of an ox, that
wasps or hornets develop from a putrid horse, and that a lot of other
bugs develop from the cheese or from the plants or from
the mud.... many
observations and many studies
had
been necessaryin order to refuse these absurd
theories ."
THE CONTRIBUTION OF SPALLANZANI AND
PASTEUR
The
hypothesis of the spontaneous generation was supported
also after Redi demonstration in order to explain the presence
of the little organisms observed in the must fermentation
and
in
the sour
milk.
In
1765 Lazzaro Spallanzani (1729-1799) made a historical
experiment that refused this hypothesis, but a century later
most of the biologists still believed in the abiogenesis.
Only
after the work of Louis Pasteur (1822-1895) this hypothesis
was definitely abandoned.
According to Pasteur, the bacteria are not born through spontaneous
generation, but develop from other bacteria or their germs, the
spores, that are transported by air.
The bacteria are able to transform chemically the fruit
juices, the milk and the other substances with them they come
into contact.
There is a wide variety of
bacteria and exist a precise correlation between
the type of bacteria and the type of fermentation.
When
the hypotheses of Pasteur on the fermentations and the infectious
diseases were exposed, they were not accepted by the medical
and scientific community.
In the opinion of
most of them, for example, the bacteria living in the blood of
a dead man had been generated by the disease itself.
|
In
order to demonstrate that the sterilized broth would
not ferment if it didn’t come in contact with the bacteria,
Pasteur prepared some
flasks with a thin, curved neck. When the organic
broth boiled into a flask, the vapour developed and sterilized
the
neck; when the flask was cooled off, the volume of the vapour
reduced itself and the air went inside, but the shape of
the neck was a trap
for the spores. The broth
in the flask, remaines unchanged still after
a
century! If the neck is broken off, the broth
ferments soon, because the germs aren't
more blocked outside.
|
|
|
