102 



PROTOZOOLOGY 



-fe 



Fig. 40. a, diagram showing the movement of Amoeba verrucosa in 

 side view (Jennings) ; b, a marine limax-amoeba in locomotion (Pantin 

 from Reichenow). ac, area of conversion; cet, contracting ectoplasmic 

 tube; fe, fiuid ectoplasm; ge, gelated ectoplasm. 



end of the amoeba, thus bringing about the movement of the 

 whole body. 



Jennings (1904) found that the movement of Amoeba verrucosa 

 (Fig. 40, a) could not be explained by the surface tension theory, 

 since he observed "in an advancing amoeba substance flows for- 

 ward on the upper surface, rolls over at the anterior edge, coming 

 in contact with the substratum, then remains quiet until the body 

 of the amoeba has passed over it. It then moves upward at the 

 posterior end, and forward again on the upper surface, continuing 

 in rotation as long as the amoeba continues to progress." Thus 

 Amoeba verrucosa may be compared with an elastic sac filled with 

 fluid. Bellinger (1906) studied the movement of Amoeba proteus, 

 A. verrucosa and Difflugia spiralis. Studying in side view, he 

 found that the amoeba (Fig. 41) extends a pseudopod, "swings it 

 about, brings it into the line of advance, and attached it" to the 

 substratum and that there is then a concentration of the sub- 

 stance back of this point and a flow of the substance toward the 

 anterior end. Bellinger held thus that "the movements of amoe- 

 bae are due to the presence of a contractile substance," which was 

 said to be located in the endoplasm as a coarse reticulum. 



