Via http://www.cns.caltech.edu/~carlos/coolpapers/, a list of ‘cool scientific papers’:

Jennifer Linden (neuroscientist) wrote:
Here are my paper suggestions. It’s been years since I read these papers, but I still remember them — the experiment is truly beautiful. The background: Normally, each eye innervates a single tectum in the frog, with no competition between the eyes. The experiment: What happens when you implant a third eye in a frog, so that two eyes are forced to innervate the same tectum? The result: ocular dominance stripes, in an animal which normally doesn’t have them. A beautifully clean demonstration that ocular dominance stripes arise from competition between the two eyes, rather than from some kind of pre-established pattern of innervation.

Constantine-Paton, M. and Law, M.I., “Eye-specific termination bands in tecta of three-eyed frogs”, Science 202 : 639-641 (1978)

Law, M.I. and Constantine-Paton, M., “Anatomy and physiology of experimentally produced striped tecta”, Journal of Neuroscience 1 : 741-759 (1981)