74 



BIOLOGY: GENERAL AND MEDICAL 



Amceboid Movement. This is movement of a kind 

 best exemplified by the Amoeba, and is a primitive form 

 of locomotion. It consists in a peculiar flowing of the 

 cytoplasm, but instead of being confined to the bound- 



FIG. 19. 



FIG. 20. 



FIG. 19. ParamoBcium caudatum, from the ventral side, showing the vestibule 

 en face; arrows inside the body indicate the direction of protoplasmic currents; 

 those outside, the direction of water currents caused by the cilia, c.v, Con- 

 tractile vacuoles; f.v, food vacuoles; w.v, water vacuoles; m, mouth; mac, 

 macronucleus ; mic, micronucleus; ce, oesophagus; v, vestibule. The anterior 

 end is directed upward. (Sedgwick and Wilson.) 



FIG. 20. Amoeba proteus: n, nucleus; c.v, contractile vacuole; N, nutrient 

 material in process of digestion; p, pseudopod; en, endosarc; ek, ectosarc. 

 (From R. Hertwig.) 



aries of the cell, it results in an extension of these bound- 

 aries in the form of what are called pseudopodia. 



Jennings has described the movement as comparable 

 to rolling. The upper surface continually passing 

 forward and rolling under at the anterior end so as to 

 form the lower surface. This causes the moving amoeba 



