Experiments on the Development of the Hind Limb of Amblystoma

Abstract

PROCEEDXNGsretarded from 1 to 3 weeks. In adults the degeneration of the optic nerve accompanies that of the retina and is accomplished during the first month. During the second month the growth of the new optic nerve from the bulb accompanies resolution of the retina. The nerve frequently approaches normal in size and passes to the optic chiasma usually along a tortuous course. In only 2 cases did the optic nerve fail to leave the bulb by the end of the second month. In these cases the nerve travelled a short distance between the retina and the choroid. In larvae a complete degeneration of the optic nerve took place during the first week although retinal change was slight compared to adult grafts. By the end of the third week it was completely regenerated in all but 4 cases ( 3 were rotated about 180°, one was normally oriented). The optic nerve was usually tortuous and less than normal in size.Regeneration in a young adult transpIanted eye was so rapid that return of vision was proven as early as the thirty-eighth day. Usual-!y this was not determined in adults until after the second month. In larvae the earliest tests for vision which gave positive results were made on the forty-eighth day (a transplant). This host was still in a larval stage. Vision was proven in all types of grafts and in many specimens by methods already published in detail.' In them the microscopic studies showed complete optic nerves. Ocular movements were present and when the hosts were in the adult stage corneal and pupillary reflexes were demonstrated.