428 JOHN LINCK ULRICH 



and the aluminum sheath. A binding post of rubber insert 

 connected by a wire the bronze spring and the brass lever. A 

 screw through one end of the sheath and the rubber insert at- 

 tached the latch to the frame of the problem. This screw afforded 

 means of making the second complete electric circuit, the other 

 being made with the binding post on the rubber insert. A wire 

 from the problem box and one from the binding post were put 

 in circuit with batteries and another signal magnet. The reac- 

 tion time for directive integration could be taken from the mo- 

 ment the hood was entered until the latch was touched. 



Another contact point had .to be attached to the problem- box 

 to record the reaction time of the neck reflex movement. A fiber 

 button supporting a light spring made contact with the alumi- 

 num sheath of the latch when the latch was raised out of the 

 notch. Contact points of platinum were connected in circuit 

 with batteries and a signal magnet. The exact height of the 

 spring was adjusted to the depth of the notch, and the height of 

 the spring, its flexibility, and the depth of the notch were deter- 

 mined by experimentation. These parts were adjusted to the 

 extent of, or to the amplitude of the neck reflex movement. 

 Since the spring gave way freely the amplitude of this movement 

 could not be said to have been shortened by the latch coming in 

 contact with the spring on the rubber button. An easy move- 

 ment of the neck reflex would be said to occur when the latch 

 was raised. 



The amount of pressure required to raise the latch out of the 

 notch was also considered. A definite amount of tension on 

 the spring which opened the door when the latch was raised out 

 of the notch, increased the pressure that must be exerted on the 

 latch. This slight pressure seemed favorable to the production 

 of the neck reflex movement, for when tension on the spring was 

 reduced, a less adequate neck reflex movement was produced, 

 and the latch was often moved only part way out of the notch. 

 Posture then was frequently inadequate, and this seemed to be 

 due to lack of work against the latch. The actual pressure 

 required to raise the latch was equivalent to 33 grams. 



