AMEBA 



43 



moves upward at the posterior end, and forward again on the 

 upper surface, continuing in rotation as long as the Amceba con- 

 tinues to progress. The motion of the upper surface is congruent 

 with that of the endosarc, the two forming a single stream" 

 (39, p. 148, Fig. n). " The movement can be imitated roughly 

 by making a cylinder of cloth, laying it flat on a plane surface, 

 and pulling forward the anterior edge in a series of waves. The 

 entire cylinder then rolls forward just as the Amoeba does " 

 (39, p. 145). Jennings's observations have been confirmed for 

 Ameba verrucosa, but do not seem to explain the phenomena in 

 moving specimens of Ameba proteus and other species (34). 



A new method of making observations has enabled Bellinger 

 (34) to add materially to our knowledge of the movements of 



Polished Edge 



FIG. 12. Diagram of apparatus designed to study Ameba in side view. 

 (From Dellinger in Journ. Exp. Zool.) 



Ameba proteus. This investigator examined specimens from the 

 side by means of the following apparatus (Fig. 12): One edge 

 of a slide was ground square and polished. Long cover slips were 

 cemented to this with the edges extending beyond the polished 

 surface so as to form a narrow trough. With the microscope 

 brought to a horizontal position, specimens pipetted into the 

 trough could be observed in side view as they moved along the 

 edge of the slide. Observations made in this way seemed tc 

 prove that Ameba moves by means of a contractile substance. 



