LIGHT REACTIONS OF NEWT 41 



entirely covered with black cloth except at the ends where the 

 light entered. Two 25-watt, 155-volt tungsten lights were used; 

 they were not tested as to candle-power, but they were of the 

 same supposed power and were of the same age. One light 

 was six inches from one end of the aquarium, the other light 

 was twenty-four inches from the other end. The first 50 obser- 

 vations were taken at five-minute intervals, except that one 

 and one-half hours intervened between observations 31 and 32, 

 during which time the animals were in the darkness. 



In 50 observations 265 animals were seen facing the more 

 distant (24 inches) light to 170 that faced the nearer and, there- 

 fore, more powerful light. Two hundred and sixty-nine animals 

 were found in the half of the aquarium nearer the more distant 

 light, 174 in the region towards the nearer light. The weaker 

 of these two lights, then, seems to have the greater attraction 

 for the animals. 



Experiment XIII. — The arrangements were exactly as in ex- 

 periment XII except that the lights were six inches and twelve 

 inches from their respective ends of the aquarium. Two and 

 one-half hours in darkness intervened between observations 19 

 and 20. In 40 observations 141 animals were found facing the 

 nearer (6 inches) light to 185 that faced the more distant light; 

 while 163 were found in the half of the aquarium towards the 

 nearer light, to 190 in the other half. The weaker of the two 

 lights seems again to be the more attractive to the animals, 

 though in a less marked degree than in experiment XII. 



Experiment XIV. — The same experimental conditions as in 

 the preceding except that the lights were twelve inches and 

 forty-eight inches from their respective ends. Between obser- 

 vations 15 and 16 was an interval of three days, and between 

 observations 45 and 46 was an interval of one day; during both 

 intervals the animals were in the dark. As in the preceding ex- 

 periment, the observations were taken every five minutes. 



In 60 observations 289 animals were found facing the nearer 

 (12 inches) light, to 229 that faced the farther (48 inches) light. 

 Two hundred and eighty-three were seen in the half of the 

 aquarium towards the nearer light, to 255 in the other half. 

 It seems that, while the differences between these sets of figures 



