32 



A. M. REESE 



this part of this experiment the temperature of the water had 

 risen about 2° C. 



In the second variation of this experiment the aquarium con- 

 taining the animals was placed out-of-doors for about five hours, 

 until the temperature of the water had fallen to 1° C ; it was 

 then brought into the dark room where the same arrangement 

 for vertical illumination of just half of the aquarium as in ex- 

 periment I was used. All of the animals at this temperature 

 were numb with cold, and lay motionless on the bottom of the 

 aquarium. One or two were apparently dead and when turned 

 over, ventral side up, made no effort to right themselves. At the 

 beginning of this series of observations six animals were placed 

 in the dark end of the aquarium and five in the light end. 



TABLE Hi 



Observations 123456789 10 



Light half 5555544444 



sssssSSsss 

 Dark half 6 6 6 6 6 7 7 7 7 7 



sssssSSSSs 



Observations . . 15 16 17 18 19 20 21 22 23 24 



Light half 6667221000 



S s s S S- S- A 



Dark half 5 5 5 4 9 9 10 11 11 11 



S S S S S- S- S A- A- A 



Observations . . 29 30 31 32 33 34 35 35 37 38 



Light half 3005 5 4 2252 



A . . . . S- a A- A- S a A 



Dark half 8 11 11 6 6 7 9 9 6 9 



S S S S- S- S A- S a A 



Observations . . 43 44 45 46 47 48 49 53 51 52 



Light half 0644533157 



.. A A- A A S S- A- a a 



Dark half 11 577688 10 64 



.. S A- s S A- S- A- A A 



Observations . . 57 58 59 60 61 62 63 64 Totals 



Light half 5 6 2 9 5 9-5 2 259 



a A A A A a a a 



Dark half 65926269 446 



A A A A A a a A 



11 12 13 14 



4 4 4 4 



s s s s 



7 7 7 7 



s S S S- 



25 26 27 28 



10 7 4 4 



S- A A A- 



1 



4 7 7 



s- s s 



39 40 41 42 



3 111 



a A A A 



8 10 10 10 

 A- A- A- A 



53 54 55 56 



6 6 8 8 



a a a a 



5 5 3 3 



a A a A 



Observations were begun at intervals of three minutes, but 



1 In this and the following experiments the letters refer to the average activity 

 of the animals at the time of observation — 



a = very active;. A = less active; A — = still less active, 

 s = very quiet; S = less quiet; S — = still less quiet. 

 A — and S — would probably be about the same state of ac tivity. 



