98 MARY HONORA SAYLE 



splashed and struggled, but several times remained in the heated 

 portion and tried to get out of the pan. In many cases they 

 stayed in the hot end for some time and burned themselves 

 over and over again, before finally reaching the middle or cold 

 end of the pan. 



From the experiments described above it is evident that 

 Necturus is sensitive to considerable changes in temperature. 

 It is apparent that Necturus could not live successfully in 

 water above 18° C. and that life in water at 30° C. would prob- 

 ably be impossible. 



THE REACTIONS TO LIGHT 



The experiments performed to determine the sensitiveness of 

 the skin of Necturus to light were carried on in a dark room, 

 the temperature of which ranged from 75°-70° F. A 144 candle- 

 meter Nernst lamp was used in all the experiments. 



The first experiment tested the reactions of Necturus to light 

 and shadow, the lamp being at the side one foot from the tank 

 and a movable screen interposed in such a way that one-ha-lf 

 of the tank was in shadow and the other half in light. Three 

 animals were successively introduced. At 23.4 candle-meters, 

 all three immediately went to the dark end of the tank. When 

 the screen was changed to the opposite half of the tank the 

 animals again moved into the shaded area. At 5.7 candle- 

 meters each animal moved about for some time, equally in the 

 light and dark areas of the tank. At 2.5 candle-meters the 

 response was slow. After three minutes all three animals moved 

 their heads and about one-half of their bodies into the shaded 

 area. When the screen was changed to the opposite half of 

 the tank the animals did not attempt to move again into the 

 shaded area but remained in the light. With the intensity at 

 1 candle-meter the response was very slow. After five minutes 

 all three moved their heads into the dark and remained in that 

 position. 



Definite reactions in determining the relative sensitiveness of 

 the body region of Necturus were brought about by illuminat- 

 ing small areas of the skin. The apparatus was in the same 

 position as for the experiments first described, except that the 

 screen was arranged in such a manner that a band of light 

 (144 candle-meters above the water at the center of the tank) 



