Another method of producing blind fish embryos consists in exposing the egg immediately, or soon after fertilization, to a temperature between 0° and 2° C. for a number of hours. Many embryos are killed by this treatment, but those which survive behave very much like the hybrids between _Fundulus_ and _Menidia_, _i. e._, a number of them have quite degenerated eyes. If the eggs have once formed an embryo they can be kept at the temperature of 0° for a month or more without giving rise to blind animals. Occasionally such rudimentary eyes were also observed when eggs were kept in a solution containing a trace of KCN. Stockard has succeeded in producing cyclopean eyes in _Fundulus_ by adding an excess of magnesium salt to the sea water in which the eggs developed or by adding alcohol, and McClendon has confirmed and added to these results. The writer tried repeatedly, but in vain, to produce _Fundulus_ with deficient eyes by keeping the embryos in the dark. Sperm and egg were not allowed to be exposed to the light yet the embryos without exception had normal eyes. F. Payne raised sixty-nine successive generations of a fly _Drosophila_ in the dark, but the eyes and the reaction of the insects to light remained perfectly normal. Uhlenhuth has recently demonstrated in a very striking way that the development of the eyes does not depend upon the influence of light or upon the eyes functioning. He transplanted the eyes of young salamanders into different parts of their bodies where they were no longer connected with the optic nerves. The eyes after transplantation underwent a degeneration which was followed by a complete regeneration. He showed that this regeneration took place in complete darkness and that the transplanted eyes remained normal in salamanders kept in the dark for fifteen months. Hence the eyes which were no longer in connection with the central nervous system, which had received no light, and could not have functioned, regenerated and remained normal. The degeneration which took place in the eyes immediately after being transplanted was apparently due to the interruption of the circulation in the eye, and the regeneration commenced in all probability with the re-establishment of the circulation in the transplanted organ.