AMEBOID MOVEMENT 

 / 2 



Figure 21. Illustrating the similarity of the movement of the surface 

 layer of Amoeba vcrrucosa with that of A. sphacronucleosus. A group of 

 three particles, connected by dotted lines for reference, change their rela- 

 tive positions as the ameba (vcrrucosa) changes its direction of move- 

 ment. Length of the ameba, 150 microns. 



cross section. It is also more in the habit of loping along the sur- 

 face in the manner described by Dellinger ('06, p. 57) so that 

 what is observed to take place in discoides in the clavate shape, 

 holds likewise for free pseudopods extended into the water out 

 of contact with a solid support (Figure 22). 



2 b 



-63 c b 4-C d 



Figure 22. Illustrating the movements of an Amoeba proteus, after 

 Dellinger. At c in stage 2 a pseudopod is projected which fastens itself 

 to the substratum as shown at c, 3, while a, 2, is pulled loose. In 4 another 

 pseudopod is projected which fastens itself at d. The ameba is not in 

 contact with the substratum at all points on its under side. 



In figure 23 is shown a clavate discoides with a small particle 

 attached to its side. The particle moved forward until it came 

 to lie at the anterior edge, 10. The speed of the particle from 

 i to 10 was 1.36 times as fast as that of the ameba, a much 

 slower rate than was observed in sphacronucleosus. At 6 a new 

 pseudopod was projected for a short distance, thus increasing 

 the amount of new ectoplasm forming in proportion to that of 

 the whole ameba. This change was reflected in the increased 

 speed of the particle, which moved 1.64 times as fast as the ameba 

 from 5 to 6. At 10 the anterior end again spread out and again 



