AMEBOID MOVEMENT 



29 



IZ'SI 



12-59 



Figure 6. Pclomyxa schicdti, after Schaeffer. b, bacterial rods char- 

 acteristic of the genus Pclomyxa. c, v, contractile vacuole. g, glycogen 

 bodies, n, nucleus, u, uroidal projections. At the left is shown a series 

 of outlines of the animal during locomotion. Length, about 75 microns. 



ectoplasm does not give way steadily at the anterior end during 

 locomotion, allowing a steady forward flow of the endoplasm, but 

 it breaks away suddenly here or there, allowing the endoplasm 

 to rush through as if it were under considerable pressure. When 

 the endoplasm rushes through these breaches in the ectoplasm, 

 it is usually deflected back along the side of the ameba for a con- 

 siderable distance, thus leaving a part of the old ectoplasmic 

 wall stand for a few seconds between the reflected wave of ecto- 

 plasm and the main body of the ameba. It is then that one can 

 observe especially well the very thin ectoplasm covering the ameba, 

 the thickness of which is about one-fortieth the diameter of the 

 ameba. This ameba is somewhat dorso-ventrally flattened and 

 generally oblong in shape during locomotion. 



Pelomyxa schiedti moves in much the same way that Amoeba 

 limicola does ; that is, by eruptive waves of endoplasm which are 

 usually deflected back along the side (Figure 6, at the left). The 

 endoplasm is likewise of very thin consistency. The thinness 

 of the ectoplasm and the ease with which it may be ruptured, 

 is very well shown by the fact that the large irregular glycogen 



