6o 



AMEBOID MOVEMENT 



in their pull upon the surface layer, thus preventing rapid forward 

 movement. 



Figure 26 shows that the surface layer flows away from the tip 

 of a retracting pseudopod that is located near the anterior end. 



-rjgure 26. Showing the comparative rate of movement of the surface 

 film over the retracting parts of the ameba. In figures 2 to 8 only a part 

 of the ameba is shown. Length of the ameba, 500 microns. 



The particle moves slowly until the body of the ameba is reached, 

 when movement becomes more rapid, 8, 9. This proves that the 

 third layer moves away from the retracting parts of an ameba, 

 no matter how large the total area of these parts may be in pro- 

 portion to the area of new surface that is being made. But whether 

 the speed of the moving third layer changes in correspondence 

 with a larger or a smaller ratio between building and retracting 

 ectoplasm has not been ascertained. 



Figure 27 shows that the relative positions of particles attached 

 to the surface layer may readily change while the ameba deploys 

 its psesudopods. Three particles marked a, b, c and connected 



