BEHAVIOR AGREEMENT AMONG ANIMALS. 3! I 



passed through the box was reflected by a 45-degree mirror into 

 the end of the grader box against dead black paper. The experi- 

 mental box was made from copper with hollow bottom and ends 

 which could be attached to a water tap by means of a hose. 

 (Fig. 37). The water in these tests was kept at I4C. bypassing 

 it through a coil immersed in water kept hot by a Bunsen burner 



(Fig. 37)- 



Aside from the general facts stated below and culled from the 

 preliminary experiments all the experiments were performed with 

 5 individuals of each species placed in the 45 deg. box in the 

 following manner. A small board was placed in front of the 

 lens so as to shut off all light from the experimental box. A 

 bottomless glass cylinder just fitting inside the box was placed 

 in the position A of Fig. 36. Five specimens were poured into 

 the cylinder. A board with a hood and i-c.-p. lamp which 

 lighted the sheet of paper on which the records were made but 

 which threw very little light into the room was used in recording 



FIGS. 38 AND 39. Showing the reactions of the animal? in the light gradient in 

 percentage in the thirds. Note differences related to the level at which the animals 

 live. Experiments performed at 14 C. 



results and when all was in readiness the board in front of the lens 

 was dropped and the cylinder removed in the same motion of the 

 arm. Readings of the position of the animals in the thirds of 

 the box were taken every 30 sec. up to a total of at least forty 

 readings. In the case of some animals like Psephenns which 

 move less rapidly after a short time, the number of readings was 



