Vol. XXX. April, 1916. No. 4 



BIOLOGICAL BULLETIN 



THE INFLUENCE OF THE NUCLEUS ON THE 

 BEHAVIOR OF AMGEBA. 1 



H. S. WILLIS. 

 INTRODUCTION. 



OUTLINE. 



PAGE. 



Introduction 253 



Material and Methods 255 



Movement 256 



Normal specimens 256 



Fragments 256 



Orientation in Light 263 



Normal Specimens 263 



Fragments 263 



Rate of Locomotion 265 



Normal Specimens 265 



Fragments 265 



Possible Causes of Differences in Behavior 267 



Size of Fragments 267 



Contractile Vacuole 267 



Position of Segments in Original Amceba 268 



Nucleus 268 



The Influence of the Nucleus upon Attachment 268 



Summary 269 



Literature Cited 270 



In the course of experimental work on Amceba in November, 

 1914, marked differences were observed in the behavior of the 

 different parts of specimens cut in two. At the suggestion of 

 Dr. S. O. Mast, an attempt has been made to ascertain whether 

 these differences depend upon the nucleus and, if so, in what 

 respects. I wish here to acknowledge my great indebtedness 

 to Dr. Mast for his helpful and constructive suggestions and for 

 his kindness in supervising both the experimental work and the 

 writing of this paper. 



1 From the Zoological laboratory of the Johns Hopkins University. 



253 



