422 C. H. TURNER 



struggling against obstacles to attain a certain known place in 

 a known environment." 



Two investigators, Szymanski and Turner, have conducted 

 experiments to test the ability of the common roach to form 

 new associations. The general method used was practically 

 identical, not because one had copied from the other, but because 

 each had been inspired by Yerkes' work on mice. A bottomless 

 glass pen, containing two compartments, one light and one dark, 

 was placed on a specially arranged electrical shocking platform. 

 In the lighted division of the pen marked roaches were placed 

 one at a time. Following its instinctive tendency, an untrained 

 roach would rush into the dark chamber. Immediately an 

 electric shock was given, which caused the roach to return to 

 the lighted portion. In the lighted compartment it would be- 

 come restless and, sooner or later, it would enter the dark sec- 

 tion. There it received another shock which caused it to return 

 to the light. Every time it reentered the dark chamber it was 

 driven out by means of electric shocks. Soon it would hesitate 

 and later turn back w T hen the dark chamber was reached. In- 

 deed, after a little training, the roach would resist attempts to 

 shove it into the dark chamber. When the roach had made ten 

 successive refusals to enter the dark chamber, the experiment 

 was concluded for that day; to be repeated on the following 

 and on a long series of successive days. 



Szymanski (95) confined his experiments to larval male 

 roaches of about the same age. Most of these were used in 

 their normal condition; but from a few the antennae were 

 amputated. Based upon their ability to form associations, 

 Szymanski divides his roaches into three classes: (1) those 

 that make rapid progress and fatigue slowly; (2) those that 

 make rapid progress and fatigue rapidly, and (3) those that 

 make slow progress and fatigue rapidly. Marked individual 

 differences were noted in the length of time that they retained 

 the acquired ha.bit; but no relation was evident between the 

 degree of permanency of the acquired habit and the number 

 of shocks necessary to instill it. Although the training influ- 

 ences the creature for only a short time, the influence of it is 

 latent. This is proven by the rapidity with which roaches 

 that have once been trained relearn the habit. It is possible 



