INFLUENCE OF NUCLEUS ON BEHAVIOR OF AMCEBA. 259 



pairs of these parts taken at random is briefly summarized in 

 Table I. By referring to this table, in which observations on 

 locomotion are recorded for 13 of the 17 individuals, it will be 

 seen that locomotion occurred in 13 of the nucleated parts, while 

 there was no locomotion in the enucleated parts. Other matters 

 in this table will be considered later. 



1.5 9 



FIG. 3. A series of camera sketches showing the reactions of a nucleated and 

 an enucleated part of an amceba in a horizontal beam of light, a-d, nucleated 

 part; 1.45-2.30 enucleated part; large arrows, beam of light; small arrows, direc- 

 tion of movement; 1.43-2.00, time at which sketches of nucleated part were made; 

 1.45-2.30, time at which sketches of enucleated part were made; mm., projected 

 scale. Note that the nucleated segment oriented fairly definitely; at a (1.43) the 

 rays of light were at right angles to the moving segment; at 1.44 the segment had 

 turned and become directed from the source of light. A similar response occurred 

 at b, c, and d after the direction of the rays of light had been changed in each case. 

 Note also that the enucleated part did not orient in the light. Both parts were 

 continuously in the same field and were subjected to the same changes in illumina- 

 tion. 



