LIGHT REACTIONS OF NEWT 47 



Experiment XXII. — This experiment was performed during a 

 fairly dark, moonless night. One-half of the wire cage was 

 covered with a board, while the other half was brilliantly illu- 

 minated by the acetylene lamp, fixed about 10 inches above 

 the surface of the water. Fifteen observations, at 5 -minute 

 intervals, were taken, during which 65 animals were noted in 

 the light half of the cage to 355 in the darkened half of the 

 cage, — a proportion of more than five to one. This proportion 

 would have been still greater but for the fact that after obser- 

 vations 2, 6 and 11 the light and dark ends were suddenly re- 

 versed, thus throwing the larger group of animals into the 

 light area. 



Experiment XXIII. — In this experiment the same cage and 

 animals were used, but the light was bright sunlight. Of course, 

 on account of the diffused light, the shaded half of the cage 

 was not nearly so dark as in the preceding experiment. In 16 

 observations, at 5-minute intervals, 103 animals were counted 

 in the light half of the cage to 297 in the dark; this proportion 

 of nearly three to one would have been greater but for the sud- 

 den reversal of light and dark ends after observations 9 and 12. 



It is evident, then, from experiments XXII and XXIII, that 

 under these conditions the negative phototropism to white light 

 is even more marked than in the laboratory experiments. 



Experiment XXIV. — In this experiment the acetylene light 

 was placed in a large, glass aquarium jar, which was sunk into 

 the water of the pond so that the light was thrown into one 

 end of the wire cage, the observations being made, of course, at 

 night. This arrangement was not very satisfactory, as the dark 

 color of the pond-water made the illumination of the far end 

 of the cage very dim. 



In 26 observations, at 5-niinute intervals, 213 animals were 

 noted in the half of the cage nearer the light to 263 in the farther 

 half. After observations 9, 20, and 22, since it was difficult to 

 reverse the ends of the cage, all the animals were pushed into the 

 light half; this tended to decrease the excess of those in the dark 

 end; but the experiment was hardly conclusive, perhaps on ac- 

 count of the unsatisfactory conditions. 



Experiment XXV. — This experiment was performed with the 

 clear sun shining down upon the end of the submerged cage, at 

 an angle varying from 40 to 25 with the surface of the pond. 



