INTELLIGENCE GF EARTHWORMS 



343 



series of five trials each were given. Only exceptionally did the 

 worm receive the shock in other than the first trial of a series, 

 and in several instances, the series were almost perfect. 



At this point in the experimentation is was decided to attempt 

 to break the habit of escaping from the T by the right arm and 

 to substitute for it a habit of escaping by the other arm. Be- 

 tween February 15 and April 9, — trials 711 to 780 — five trials 

 per day were given with the sandpaper and electrodes in the 

 right arm, instead of in the left, and with the exit tube at the 

 end of the left arm. 



Under these conditions the worm persistently turned to the 

 right, in accordance with its previous training. So strong was 

 this tendency that in the consecutive series of April 6, 7 and 9 

 not a single correct trial appeared (table 5, left side). 



TABLE 5 



Results of Attempt to Break up Habit op Turning to Right in T. 



and Establish the Habit of Turning to the Left 



Turning to Right 



Date 

 April 5 



Turning to Left 

 Sand- 

 paper Shock Time 



Trial 

 761 

 762 

 763 

 764 

 765 



200" 

 53" 

 134" 

 260" 

 119" 



Date 

 April 10 



Av. of five trials 2.6 1.0 153.2" 



April 6 



766 

 767 

 768 

 769 

 770 



248" 

 193" 



65" 

 107" 



65" 



Trial 

 781 



782 

 783 

 784 

 785 

 786 

 787 

 788 

 789 

 790 



Av. of ten trials 



Sand- 

 paper Shock 



Av. of five trials 3.2 1.4 135.6" 



April 11 



April 7 



771 



772 

 773 

 774 



775 



149" 

 172" 

 170" 

 145" 

 92" 



791 



792 

 793 

 794 

 795 



Time 

 31" 

 67" 

 40" 

 58" 

 30" 

 39" 

 42" 

 44" 



148" 

 54" 



Av. of five trials 



Av. of five trials 2.6 1.8 145.6" 



April 12 



April 9 776 

 777 

 778 

 779 

 780 

 of five trials 



Av. 



5 

 6 

 4 

 3 

 2 

 4.0 



173" 

 490" 

 189" 

 151" 

 111" 



796 

 797 

 798 

 799 

 800 



Av. of five trials 



.1 55.3" 



130" 

 54" 

 45" 

 57" 



45" 



66.2" 



97" 

 28" 

 51" 

 36" 

 65" 



55.4" 



1.4 222.8" 



After 70 trials, this attempt to break the direction-habit 



