MODIFICATION OF RESPONSE IN AMCEBA. 59 



It will be remembered that each series was interrupted ir- 

 regularly l>v longer intervals of time, usually about a day or 

 longer. Despite this there is a general constancy of the tendemy 

 throughout each series. This seems to indicate ability to retian 

 for some time the modification of response. 



These experiments were repeated 18 months after the preced- 

 portion of the paper was completed. Two individuals were 

 used and a series of 18 readings approximately 3 minutes apart 

 uc ic obtained with each. The total number of contacts made by 

 ilu-se two individuals in groups of three consecutive trials be- 

 ginning with the first follows: 20, 9, 10, 6, 7, 4. The results ob- 

 tained in these observations are consequently in harmony with 

 ili">e obtained in the preceding observations. 



SUMMARY. 



\Vfim AiiKL'ba repeatedly comes in contact with a band of 

 intense light the number of attempts to continue in the original 

 iliicc tion decreases as the number of trials increases. 



This indicates that there is some change in Amoeba that is 

 analogous to what is called "learning" in the higher animals. 



LITERATURE CITED. 

 Gibbs, David and Dcllinger, O. P. 



'08 1 IK- Daily Life of Amoeba prolfus. Am. Jour. Pay., Vol. 19. pp. ! 

 Mast, S. O. 



'10 Reactions in Amoeba to light. Jour. Exp. Zool., Vol. 7. pp. 265- 

 Schaeffer, A. A. 



'17 ' 'od in Amoeba. Jour. Animal Behavior. V"' .'^0-258. 



Schaeffer, A. A. 



'17 Reactions of Amoeba to Light and the Effect of I.i.nht .:UK. BIOL. 



BULL.. Vol. 32. pp. 45-72. 



