INFLUENCE OF NUCLEUS ON BEHAVIOR OF AMCEBA. 265 



RATE OF LOCOMOTION. 



Normal Specimens. The rate of locomotion varies greatly in 

 different individuals. Some specimens move nearly twice as 

 fast as others. Quite a number of individuals were observed to 

 move rather consistently at 0.27-0.3 mm. per minute; others 

 moved at an average rate of 0.12-0.15 mm. per minute. There 

 is a fairly definite relation between the size of the moving organ- 

 ism and the rate of movement. An animal travels a distance 

 that is approximately two thirds the length of its body in one 

 minute. The actual distance traveled by a large animal is 

 greater for a given length of time than the actual distance traveled 

 by a small animal for the same length of time under the same 

 conditions. This is clearly demonstrated by the results recorded 

 in Table II. By referring to this table it will be seen that the 

 ratio of the distance traveled per minute to the length of the 

 body of the specimen is approximately the same in all cases. 



TABLE II. 



Relation between size of Amoeba and rate of locomotion. The average rate of 

 locomotion was computed from five readings extending one minute each. The 

 average length was computed from five measurements of the moving organism 

 at intervals of one minute each. The rate was measured by projecting the moving 

 organism on a scale with a camera lucida. 



Ratio of Distance Traveled 



Maximum Length of Specimens Average Distance Traveled per Minute to Length 



Observed. per Minute. of Body. 



0.36 mm. 0.24 mm. 0.66 



0.34 0.20 0.59 



0.35 " 0.23 " 0.65 



0.37 " 0.24 " 0.65 



O.2I " 0.15 " O.?! 



0.26 " 0.17 " 0.64 



O.2O " 0.14 " O.72 



0.26 " 0.17 " 0.64 



Fragments. In the work on the rate of locomotion in frag- 

 ments, the two parts were on an average approximately the same 

 size. Observations were made on each pair of segments at about 

 the same time. Both were kept under the same cover-glass 

 and in the same environment. It was found that the rate of 

 movement in nucleated fragments, like that in normal specimens, 

 bears a definite relation to the size of the body. Large nucleated 



