14 BEHAVIOR OF THE LOWER ORGANISMS 



the cyst, whereupon the Amoeba turned and again followed the rolling 

 ball. At times the animal sent out two pseudopodia, one on each side 

 the cyst (as at 4), as if trying to enclose the latter, but the spherical cyst 

 rolled so easily that this did not succeed. At other times a single, long, 

 slender pseudopodium was sent out, only its tip remaining in contact 

 with the cyst (Fig. 19, 5); then the body was brought up from the rear, 

 and the food pushed farther. Thus the chase continued until the roll- 

 ing cyst and the following Amoeba had described almost a complete 



FIG. 19. Amoeba following a rolling Euglena cyst. The figures 1-9 show successive 

 positions occupied by Amoeba and cyst. 



circle, returning nearly to the point where the Amoeba had first come 

 in contact with the cyst. At this point the cyst rolled to the right as it 

 was pushed forward (7). The Amoeba followed (8, 9). This new path 

 was continued for some time. The direction in which the ball was 

 rolling would soon have brought it against an obstacle, so that it seemed 

 probable that the Amoeba would finally secure it. But at this point, 

 after the chase had lasted ten or fifteen minutes, a ciliate infusorian 

 whisked the ball away in its ciliary vortex. 



Such behavior makes a striking impression on the observer who 



