Grafted Eyes of Young and Old Adult Salamanders (Amblystoma Punctatum) Showing Return of Vision *

These experiments are part of a series which the senior author has been making on the grafted vertebrate eye in fishes, amphibians, and mammals. In all of the vertebrates studied the eyes were completely excised and then eith-er reimplanted in the same orbit or transplanted to the denuded orbit of another host. In placing the graft, care was taken to re-establish the normal orientation. In the forms so far studied in this laboratory, it may be briefly stated that the grafted functional eyes of fishes and mammals are somewhat alike in the fact that the retina and optic nerve undergo extensive degeneration followed by no regeneration, thus inhibiting return of function. In certain types of amphibians restitution in the grafted eye provides quite a different story. In this group alone more than 1000 grafted functional eyes have been studied in animals of various species and at various stages. 9 10, 11, 12, 13, 14, 16, 17, 19, 20, 21 In the anurans (frogs) the grafted tadpole or larval eyes have shown that the retina survives the operation, but that the optic nerve possesses no power for regeneration. On the other hand, in urodeles (salamanders) the optic nerve and the retina have a great capacity for regeneration. This was shown in the larvae of the species, Amblystoma punctatum,8' 20 and in other species of adult salamanders referred to in the literature already mentioned. Eyes can be exchanged with success in one16 or both8 directions between animals of different species. In one type (adult Triturus viridescens) return of vision can even be obtained repeatedly in the same eye after several transplantations. A colored motion picture has been recently prepared recording these experiments.12 The present report gives