INFLUENCE OF NUCLEUS ON BEHAVIOR OF AMCEBA. 269 



results obtained in the study of one pair of segments taken from 

 the same specimen is typical of all. In this case the parts were 

 approximately equal in size and the nucleated part was cut from 

 the anterior end of the amoeba. 



At five minutes after division both fragments were attached 

 and moving. Three minutes later the attachment in both was 

 broken by the sliding of a small glass rod under them. The 

 nucleated part began immediately to send out pseudopods aim- 

 lessly. This continued for two minutes; then the segment 

 attached and remained so for three hours when the experiment 

 was brought to a close. This segment was attached continu- 

 ously to the substratum; it appeared to be attached usually at 

 three different points and the behavior appeared to be normal in 

 every respect. The enucleated segment was momentarily at- 

 tached at several different times, and each time the attachment 

 was so w^eak that it could not resist even the slightest jar given 

 the table on which the experiment was made. At no time was 

 this segment continuously attached longer than two minutes 

 and it was never attached at more than one point at a time. 

 There was a slow streaming motion in the protoplasm but no 

 locomotion at all except for a short time during its first attach- 

 ment and then it was very slight. The results obtained in all 

 of the observations on the attachment of segments of Amoeba 

 are briefly summarized in Table I. By referring to this table it 

 will be seen that attachment of nucleated parts to the substratum 

 is continuous; that attachment of enucleated parts is intermittent, 

 slight and of short duration. 



These facts seem to indicate that the nucleus directly in- 

 fluences the attachment of protoplasm to the substratum and 



thus influences behavior. 



SUMMARY. 



1. Amceba proteus moves regularly and smoothly by alternate 

 formation of pseudopods on the two sides of the organism. 

 Locomotion in segments of Amoeba with a nucleus is of the same 

 general character. Movement in segments without a nucleus, 

 however, is irregular, jerky, very much slower than that in 

 nucleated parts, and the pseudopods are not ordinarily formed 

 regularly or alternately. 



2. In a horizontal beam of light, normal specimens direct 



