394 JOHN LINCK ULRICH 



In the majority of cases, it is the ineffective pushing of the 

 snout into the mesh of the door just underneath the latch that 

 eventually, with the crouching of the body, produces the neck 

 reflex movement. Pushing is not effectively performed against 

 hard resisting substances, and the body is immediately crouched 

 and set. If at this time, the rat's muzzle or head comes at any 

 instant in contact with the latch, an upward movement of the 

 head and the body occurs. At times posturing of the body is 

 not very pronounced when the latch is touched, but becomes so 

 immediately on the contact of the rat's muzzle with the latch. 

 In many cases, it is necessary for the latch to give away before 

 posturing with the production of the neck reflex and the raising 

 of the latch take place, just as the continuation of digging, or 

 moving with the muzzle light substances is conditioned by these 

 substances moving in order that the act be completed. Hard 

 resisting substances produce ineffective movements. 



All movements performed have a cumulative effect on the rat, 

 increasing in many ways its efficiency. That such an effect from 

 all activity is necessary for the production of the neck reflex 

 movement, can be detected by observing closely the movements 

 of individual rats. This effect is most evident in those rats in 

 which the solution of the problem box comes early on the first 

 trial. Two excursions around the problem box with the same 

 number of tussles at the door, are quite sufficient to produce the 

 neck reflex which raises the latch. All movements are quickly 

 performed and reflex excitability persists almost to the point 

 where solution occurs, then it subsides. With other rats, this 

 cumulative effect, though not so observable, is nevertheless 

 present. Besides the effective movements made at different parts 

 of the problem box, ineffective movements are made repeatedly 

 at the door before the latch is raised. Reflex excitability may 

 be excessive, sporadic, or may not persist. When in rats 

 excitability is excessive, considerable energy is used in rais- 

 ing the latch. Often it is thrown far out of the notch. Postur- 

 ing under the latch is then excessive. Apparently many responses 

 and organic changes are necessary to fit the organism for the 

 production of the neck reflex, without which it is quite evident 



