LIGHT REACTIONS OF NEWT 39 



The same animals and arrangement of apparatus were used 

 as in experiment V, the only difference in the experiments being 

 that in the present one, table V, the aquarium containing the 

 animals had been placed outdoors for three hours, until the 

 temperature of the water had fallen to 0° C. and a thin skim 

 of ice had formed. 



As in experiment II the animals at the beginning of the obser- 

 vations were all stationary, as though dead, and were evenly 

 scattered over the bottom of the aquarium. Observations 1 to 

 6 were taken at ten-minute intervals ; 7 to 40 were at five-minute 

 intervals. After observations 5, 17 and 30 the ends were re- 

 versed, thus putting the animals from the far to the near end 

 of the aquarium; this, of course, raised the total number for 

 the far end and lowered the total number for the near end. For 

 the first 3 observations, or one-half hour, practically no change 

 in the position of the animals took place; at this point warm 

 water was carefully added until the temperature of that in the 

 aquarium was raised to 8.5° C, and by the end of the experi- 

 ment the temperature had slowly raised until it was 12.5° C. 

 After the addition of the warm water the animals began to 

 show signs of life, though they remained rather sluggish to the 

 end of the experiment. 



In 40 observations 122 animals faced towards the light to 

 231 away from the light; 140 were in the near half of the aqua- 

 rium, 266 in the half farther from the light. 



Experiment X. — This was a continuation of the preceding ex- 

 periment under exactly the same conditions except that the 

 temperature of the water at the first observation was 4.5. C. 

 instead of 0° C, and the animals were moving about very slowly 

 instead of lying perfectly still. After the 4th, 5th and 14th 

 observations all the animals were pushed into the near half 

 of the aquarium. Observations were somewhat irregular, being 

 every ten minutes for about the first half of the observation, every 

 five minutes for the latter half of the observations. After ob- 

 servation 16 warm water was added until the aquarium tem- 

 perature was 23.5° C. ; the dark room being cold, this tempera- 

 ture was lowered 2° by the end of the experiment. In 28 

 observations 134 animals were found facing the light to 147 

 that faced away from the light; while 107 animals were counted 



