If you're talking about what I think you're talking about, the fact that it is not "scientifically valid" might have a lot to do with it.
Cell Theory
experiments test the scientist theory
The scientist who tested and proved Oparian's theory was Stanley L. Miller and Harold Urey.
The theory is modified.
it is an educated guess that can be tested by experiment
Look for the answer in your book. Its there.
Emil Krapilin.Freud is a fraud. Ignore him.
theory
몰라씹새야
ideas
The Atomic Theory
cell theory
Cell Theory
experiments test the scientist theory
theory
Because sOMETIMES THERE ARE MANY proofs
the russian scientist pavlov.