312 Journal of Comparative Neurology and Psychology. 



when the light is passed back and fourth over the long axis of 

 the body. When the light is in front the head is bowed down 

 and when it is passed behind the body the head is tilted up- 

 ward. Both the lateral and vertical movements are such that 

 they tend to place the upper surface of the head at right angles 

 to the direction of the rays. The vertical movements, like the 

 lateral ones, are at first slight, and increase in vigor the longer 

 they are caused to continue. The animal performs these move- 

 ments with machine-like regularity and precision and without 

 showing the least activity in any other part of the body. If 

 the light is moved around the body in a circle the head will 

 follow it with a corresponding rotary motion. If the light is in 

 front and to the right of the animal the head will be tilted over 

 to the right and at the same time pointed downward in front ; 

 or if the light is to the left and behind the animal the head 

 will be tilted over to the left and raised up in front. For each 

 position of the light there is a corresponding attitude of the 

 head. The orientation of the head is remarkably precise. By 

 carefully watching the tip of the beak with a lens as the light is 

 moved it may be observed that a change of only two or three 

 degrees in the direction of the rays produces a corresponding 

 change in the direction in which the head is pointed. 



After some time the movements of the head are accom- 

 panied by movements of the breathing tube. When the light 

 is in front of the body the tube is lowered ; when it is carried 

 behind the body the tube is raised. These movements are at 

 first slight but they become more decided and more regular the 

 longer they are continued. Lateral movements of the breath- 

 ing tube in response to light do not occur. 



The next movements to appear are those of the limbs. 

 The animal, after a time, shows irregular twitchings of the leg 

 muscles, and soon afterwards slowly and unsteadily raises itself 

 upon its legs and stands as if undecided whether to walk away 

 or subside again into a state of repose. If now the light is 

 passed over the body from side to side the creature will perform 

 swaying movements each time the position of the light is chang- 

 ed. If the light is on the right, the back of the insect is tilted 



