REACTIONS OF WHIP-TAIL SCORPION TO LIGHT 



259 



ing sometimes away from, and sometimes toward, the observer. 

 Reactions were measured in degrees of deflection from the direc- 

 tion in which the animal was headed when subjected to the 

 stimulus. Four animals were used in this and in each of the 

 following series of measurements. Each animal was given ten 

 trials. With the limited material at my disposal, it was not 

 possible to use greater numbers of animals and cover the ground 

 adequately. The forty reactions measured for each case, how- 

 ever, are sufficiently consistent to indicate that the results are 

 essentially the same as would be obtained with a greater num- 

 ber of animals. The measurements are collected in table 1. 



TABLE 1 



Reactions of Mastigoproctus to lateral illumination of 120 candle meters. The 

 measurements are recorded in degrees of deflection from an initial -path of loco- 

 motion. In figure 3, B the same measurements are plotted graphically 



An inspection of the individual reaction measurements and the 

 averages will give a clear idea of the consistency of the responses. 

 There is not a single positive reaction among the forty trials, 

 and only two negative reactions as low as 40 degrees. When 

 it is considered that to attain, under these experimental condi- 



