Theory of Spontaneous Generation
Name: Jessica B.
I am doing an experiment about the Theory of Spontaneous
Generation. I have done three tests with bread then placing them in petri
dishes. The first bread was dry, second got 40 water drops and third got
40 sucrose drops (5% sucrose solution). I wanted to know which one should
mold the most after one week, i know it isnt dry but between the other
two i hav no idea. How would i disagree with Spontaneous Generation (what
would be my reasons) and how would i explain to non believers that life
does not evolve from non-life? Thank you in advance.. I am in deep need
First, you should probably re-name your project. Spontaneous generation implies that life can
arise from non-living substances. Your mold growth experiment will simply test how quickly
already living mold spores can settle upon and grow in the media you've selected. The
experiment you are carrying out will not test whether life can arise from that which is
not or ever has been alive.
Probably the best argument against spontaneous generation is the fact that no experiment
ever performed has produced any living material from dead atoms. Indeed, many experiments
have demonstrated that precursors (building blocks) of life can be produced in the lab.
However, no unguided, random combination of simple dead elements has ever produced any
material that meets the criteria of a living organism. Much as some scientists would like
to believe and prove otherwise, although it can be sustained by that which is not alive,
life has not yet been produced from non-living material.
The "original" experiment refuting "spontaneous generation" was done using
common house flys and maggots. When raw meat at room temperature was covered
with a cloth tent so that the flies could not land on the meat -- no maggots
hatched. The uncovered meat produced maggots because the flies were able to
lay their eggs in the meat hence producing the maggots. The experiment you
are doing is more difficult because your "test life" is bread mold and mold
spores being so much smaller can be carried by air currents to the bread.
However, there is a way to do the experiment, I think.
Make a growth medium. It could be sugar and bread, or a commercial agar
growth medium that you should be able to buy through your school. Sterilize
the growth medium and the petri dishes by boiling them for about 10 min. to
kill of all bacteria and mold. You could also use canning jars. You need to
keep both samples wet by adding boiled sterile water to each every couple of
days so that "drying out" is not a factor. You will have to arrange some
sort of syphon to add sterile water without opening the sterile control.
Possibly a piece of rubber tubing that you sterilize with ethanol or
isopropanol prior to "watering your garden" so to speak. This is the tricky
Then keep one dish open for say an hour each day. Keep the other one
covered. In a few days the one you keep open each day should pick up some
spores of some sort of "invisible" life force -- but the other one shouldn't
if you are careful to maintain its isolation from drafts of air.
Nonetheless, given you are dealing with microscopic invaders, you will
have to be really careful.
It is tempting for me to give you the proper experimental procedure to
follow but this is a great opportunity for you to do some research and then
put your imagination to work with some sound reasoning. I suggest you look
up the works in spontaneous generation done by Pasteur, Reti, and
spallanzani. Pasteur's work might be the easiest to work from... chicken
There are two ways you can go here. You can operate on pure belief, and
simply have faith that what you believe is true; or you can use science
to try to find out what is true. You can't do both at once, because
belief before proof is the opposite of science. It is one thing to make
an initial guess, for the purpose of organizing a program of research in
which you try honestly to discover what is true. It is an entirely different
thing to begin with a belief, focus your attention on facts that seem to
support your belief, and try to explain away or minimize the importance of
facts that seem not to support it. If you're going to use science, the
first thing you have to be is honest.
Some things can be proven, and some things cannot. I don't know whether
or not spontaneous generation is actually possible, and I can live without
having an answer. But I can't think of any single step in the process
that has been shown to be impossible, or even seems likely to be shown so.
First of all, your experiment doesn't have anything to do with spontaneous generation. It only
shows that mold needs moist conditions to grow and will grow faster with a more concentrated
source of carbon (sugar). If you refer back to Pasteur and Needham and Spallanzani, they
were trying to demonstrate that life could not generate within a closed system. For example,
Pasteur devised a way of sterilizing (made free of living things) a broth yet leaving it open
to the air. He made a "swan necked" flask that prevented bacteria and fungi from entering the
flask, yet let oxygen in. It didn't show signs of life for over a year, until he broke off the
neck which allowed dust and fungi to enter. What you need to do is somehow sterilize the bread
in a closed container, and have a control of the same set up with bread that is not sterile or
is not closed and see which grows mold. The closed container shouldn't grow anything, as long
as bacteria and mold are prevented from getting to it. You need to show that the life is not
coming from within the system, only from outside of it.
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Update: June 2012