Evidence That Cut Optic Nerve Fibers in a Frog Regenerate to Their Proper Places in the Tectum.

The frog's retina projects into the superficial neuropil of the opposite tectum in four functionally different layers of terminals. Each layer displays a continuous map of the retina in terms of its particular function. The four maps are in register. The fourth-dimensional order is reconstituted after section and regeneration of the optic fibers.