Pasteur's Swan Necked Flask Experiments

Louis Pasteur postulated that microbes grew in broth because the broth was exposed to microbes in the air. These microbes would get into the broth from the air and grow.
The other idea was in line with the Theory of Spontaneous Generation, that the microbial growth in the broth was due to the "vital force" which was a spiritual force in the air that was thought to cause spontaneous generation.
In order to put these ideas to the test, Pasteur designed special swan-necked flasks that were designed to allow air through while trapping microbes.in 1675 antoine van Lewin hook was
actually given the honoring title of the
father of microbiology Anton van Lewin
hook was claimed the father of
microbiology because he observed the
first motile motile meaning mobile or
able to move around so the first motile
microscopic organisms he called these
organisms anima cules anima culés he
gathered these animals from a drop of
pond water that he had collected bamboo
and hook also discovered the first
bacterial cells had already been
discovered by hub but those were plant
cells animal cells and bacterial cells
were discovered by Van Leeuwen hook
before this time microorganisms were
hypothesized but never actually observed
many people were resistant to the idea
that something could exist that was
actually too small to be seen with the
naked eye it was not until the invention
of the microscope that this micro world
was able to be observed early
microscopes did not have much magnifying
power until 1675 when Anton van leeuwen
Hooke developed the first microscopic
lenses powerful enough to observe these
microorganisms these improvements
resulted in a magnification of up to 300
X Louis Pasteur was known for creating a
lot of different things including our
pasteurization processes that we still
use today
Louis Pasteur performed a series
experiments that presented overwhelming
evidence against the theory of
spontaneous generation
many consider Louis Pasteur's
experiments to be the death blow to the
theory of spontaneous generation so
first some background the controversy at
the time was how microorganisms were
able to grow in bra
broth is a nutrient medium that has
nutrients that micro organisms need to
live brah had already been developed and
they had been using this to grow
microorganisms and labs it had been
observed already that microbes were able
to grow in nutrient-rich broth but there
was a debate as to why or how this
occurred Louis Pasteur postulated that
microbes grew in broth because broth was
exposed to microbes existing in the air
too small to be seen with the naked eye
these microbes would get into the broth
from the air and then reproduce over a
few days growing enough to be seen the
other idea was in line with the theory
of spontaneous generation this idea was
that the microbial growth observed in
the broth after sitting out on the
counter for a few days was due to
something that was called the pneuma or
the vital force the pneuma or vital
force was like this spiritual force in
the air that was able to cause
spontaneous generation so basically
these microorganisms were able to
spontaneously generate out of the broth
in order to put these two different
hypotheses to the test
Louis Pasteur created the swan neck
flask the swan neck flask was designed
to allow air through or the pneuma or
vital heat through but it would actually
trap any microorganisms
here we see a diagram of the experiment
at the beginning of the experiment broth
was boiled to make sure that there were
no microorganisms existing in the broth
at the beginning of the experiment then
the swan neck flask with broth were
incubated for a few days
NUMA or vital heat had access to the
broth during this incubation period but
any microorganisms that would be in the
air would not have access to the broth
after the incubation was done they found
no microbes no microorganisms the vital
heat and numa was able to get through
but no microbes so when they repeated
the experiment but this time they broke
off the swan neck portion of this walnut
flaps these organisms that you couldn't
see that were just hypothesized to be in
the air now did have access to the broth
and they waited three days for the
incubation and lo and behold there was
growth in the broth and so the
microorganisms did grow and the
microorganisms were found at the end of
the incubation
[Music]
Pasteur's swan-neck experiments
disproved the theory of spontaneous
generation and gave overwhelming
evidence that microorganisms exist