INTELLIGENCE OF EARTHWORMS 351 



Since it had been demonstrated that the previously acquired 

 direction-habit had disappeared from the regenerated worm 

 after an interval of four weeks' rest, training was instituted 

 for the purpose of re-establishing the habit. 



Gradually the behavior changed; the number of mistakes 

 diminished and the trips became more direct. The data of 

 table 8 indicate the nature and rapidity of the change which 

 occurred between July 4 and July 22. Only one mistake was 

 made in each of the series on July 16, 18, and 22. 



It would seem therefore that worm No. 2, having (1) acquired 

 a certain direction-habit as the result of systematic training, 

 (2) lost the habit by reason of the regeneration of the ganglia 

 of its anterior segments, and (3) exhibited a tendency to turn 

 in the opposite direction to that demanded in the memory tests, 

 which tendency (4) later was overcome by systematic training 

 and gave place to a definite direction-habit. 



SUMMARY 



1. The manure worm Allolobophora foetida, is capable of 

 acquiring certain modes of reaction which involve a definite 

 direction of movement and the association of two stimuli. 



2. The habit appears as a result of from 20 to 100 experi- 

 ences. It is inconstant even when perfectly formed, varying 

 markedly with the physiological condition of the worm ("good" 

 and "bad" days) and with imperfectly controlled external con- 

 ditions (temperature, moisture, light, etc.). 



3. The results of training on the basis of five trials a day, 

 or every other day, are more satisfactory than those obtained 

 with 10, 15 or 20 trials a day. 



4. There is a tendency to "track" (follow the slime or 

 mucous path) if the apparatus is not thoroly cleansed between 

 trials, but this tendency is not sufficiently strong or constant 

 to yield perfect series. 



5. Evidences of the effects of experience appear thruout the 

 systematic training in (a) the increased readiness to enter the 

 apparatus and to desert it for the exit tube; (b) the evident 

 "recognition" of the exit tube; (c) the gradually increasing 

 avoidance of the sandpaper, which was meant to serve as a 

 warning against the electrical stimulus; (d) the acquired ten- 

 dency to avoid contact with the electrodes ; (e) the disappearance 



