OPTOKINETIC TESTING OF CYCLOPEAN AND SYNOPHTHALMIC FISH HATCHLINGS

¹ Department of Zoology, Oberlin College, Oberlin, Ohio, and The Marine Biological Laboratory, Woods Hole, Mass.

1. Perfect cyclopean, closely synophthalmic, and anophthalmic fish hatchlings were obtained by magnesium chloride treatment or by hybridization.

2. Synophthalmic fish, with distribution of optic nerve fibers generally similar to controls, responded essentially normally to a horizontally rotating optokinetic drum.

3. A synophthalmic fish, with optic fibers distributing to the telencephalon of one side, failed to respond to the drum.

4. A fish with only one functional eye in the synophthalmic position, and optic fibers distributing entirely homolaterally, responded in the opposite direction when the drum was rotated toward the blind side.

5. Although there was other, somewhat inconclusive, evidence that they could see, eight perfect cyclopean fish failed to respond to a horizontally rotating drum.