Darwin's theory breaks down.

"If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case."
Charles Darwin, The Origin of Species,

Well Mr. Darwin, consider this case:
http://www.veritas-ucsb.org/library/origins/GRAPHICS-CAPTIONS/Flagellum.html

Bacterial Flagellum

www.veritas-ucsb.org

The bacterial flagellum is an example of what Michael Behe describes as an irreducibly complex system. In his book, Darwin's Black Box, he explains that such irreducibly complex systems could not have arisen by a gradual step-by-step Darwinian process.