S.i 



J. S. SZYMANSKI 



having received many shocks. Perfection was gained only 

 after a long time, but the fact that the curves Nos. 3 and 5 

 show two crests is particularly interesting. The one is a definite 

 one, the other takes place about the middle of the course of 

 the curves. The curve for No. 10 presents three crests. While 

 the interest of the crests consists in their showing the progress 

 of the learning, the space between the crests may be considered 

 as the consequence of fatigue. I noticed external signs of 

 fatigue, in all the cockroaches referred to, after the first crest 

 had been attained. The animal remained motionless on the 



40 

 9 



& 



I 

 6 

 S 



3 

 2 

 A 

 



*K 



i H 

 J/' 



SI 



1 .- 

 A 



7 / " 



A 

 n 



! 



\ 



\ / 



JO 



10 



30 





so 



Figure 2. Representation of the reactions of cockroaches Nos. 2, 4, 6, 7, and 

 8. Number of turnings from dark box indicated on axis of ordinates. Num- 

 ber of electric shocks indicated on axis of abscissas. 



same spot or when excited to movement shot blindly along 

 the walls, failing to stop on the boundary line between light 

 and darkness. In the same way, the movements of the thorax 

 and the antennae, previously described, ceased when the animal 

 had arrived at the boundary line. The effect of the electric 

 shocks upon the animal seemed to be lessened. As soon as the 

 animals had rested, they were able to attain the second crest 

 and the experiments were completed. 



The tests of No. 10 were achieved in the same trial, those 

 of No. 3 after the elapse of one day, and those of No. 5 after 

 two davs. Thus the two elements of these curves, crests and 



