632 



the same direction as the central current, while the attached 

 parts of the surface are at rest. The movement of Amoeba is 

 thus of a rolling character ; the upper surface continually passes 

 around the anterior end to form the lower surface ; this then 

 remains quiet until it is taken up by the posterior end as the lat- 

 ter moves forward. The movements in an advancing Amoeba 

 are indicated in Figure 3. In a projecting pseudopodium the 

 movements are of the same character as those at the anterior 

 end (Fig. 3), save when the pseudopodium projects freely into 



the water, being nowhere in contact with a solid. In the latter 

 case the entire surface moves outward, in the same direction as 

 the tip. 



Details of the obser\ations and experiments which demon- 

 strate the movements to be of the character just set forth are 

 given in an extensive paper published elsewhere (Jennings, :04). 

 The movements were determined chiefly by observing the motion 

 of objects attached to the outer surface of Amoeba, of objects 

 partly imbedded in the outer layer, and of particles within the 

 body. The movements as thus studied are clear, and exclude 

 the possibility of the typical existence of backward currents on 

 the surface. 



It appears then that Amoeba does not move in the same man- 

 ner as do the imitations based on local changes in the surface 

 tension of a fluid mass. The currents which form the charac- 

 teristic features in the latter case are not present in Amoeba. 



