180 LESLIE B. AREY 



More recently Fujita ('11) asserted that after the head 

 and forward extremities were bound with wet black cloth and 

 the rest of the body was exposed to sunlight for 15 to 20 minutes, 

 the 'eyes' remained in the dark-adapted condition. 



I, myself, before learning of Fujita's work, had performed 

 several experiments of the same kind. The head and fore body 

 of dark-adapted frogs were bandaged with many thicknesses 

 of black velvet and the remainder of the body and the hind legs 

 were exposed to direct or diffuse sunlight for periods of 15 minutes 

 to 1 hour. Care was taken to keep the skin moist and to 

 guard against the heating tendency of direct sunlight by using 

 a heat filter. Although the animals were in an active condition 

 at the end of the experiment, there was in no case a distinct 

 change in the position of the cone cells or retinal pigment as 

 Englemann maintained. 



In an unpublished investigation by Mr. S. G. Wright, no 

 direct responses were observed when Ameiurus, from which 

 the eyes had been removed, were illuminated with the light 

 of an electric arc. The normal fish, as is well known, is a night 

 feeder, yet it also frequented equally the light and dark halves 

 of an aquarium jar. 



It is, conceivable, however, that the soft skin of this animal 

 contains a photoreceptive mechanism, even though the motor 

 responses to light fail to indicate its presence. One of the pos- 

 sible ways in which an integumentary photosensitivity could 

 be manifested is through an influence on the position of the 

 retinal elements, similar to the relation which Englemann be- 

 lieved to exist in the frog. In view of such a possibility several 

 experiments were performed in which dark-adapted fish with 

 bandaged heads were exposed to daylight and to the light of 

 an electric arc for periods of 45 minutes to 1 hour. In no 

 case, however, was there the sHghtest tendency toward movement 

 on the part of the rods, cones, or retinal pigment. 



These results indicate that neither in the frog nor in Ameiurus 

 are movements of the retinal pigment or visual cells evoked 

 by a cooperation of dermal photosensitivity and 'retino-motor' 

 nerve fibers. Consequently, Englemann's experiment does not 



