68 PROTOPLASM AND THE AMOSBA. PROTOCOCCUS 



exact specific form of body and function, are certainly 

 carried mainly, if not entirely, by the chromatin in 

 reproduction, in which the nuclei of the reproductive 

 cells play the leading part. Often indeed the nucleus 

 of one of the parent cells of the new organism, is prac- 

 tically the only thing contributed by that parent 

 to the new organism, which may neverthekss exhibit 

 some of the characteristics of that parent in a perfectly 

 pure form. 



Life Processes of Amceba. — The most obvious thing 

 the amoeba does is to move. When the animal is active 

 its shape continually changes, the clear ectoplasm 

 thrusts out from the body and is followed by the stream- 

 ing granules of the endoplasm. The protoplasm of 

 the projection so formed (pseudopodium) gUdes along 

 the surface to which the amceba adheres, and may be 

 followed by the streaming forward of the rest of the 

 body, which thus gradually ghdes away from the 

 position it occupied at first. Thus the animal con- 

 stantly changes its shape * and at the same time its 

 position. Locomotion (movement from place to place) 

 follows as an immediate result of the streaming move- 

 ment of the protoplasm in a constant direction. The 

 protrusion of pseudopodia is not, however, necessarily 

 followed by locomotion : several pseudopodia may be 

 put out at different spots on the surface of the body 

 and again withdrawn, so that no continuous streaming 

 in one direction occurs. Different species of amceba 

 vary very considerably in the shape and dimensions 

 of their pseudopodia. 



The streaming movement of the pseudopodia is also 

 one method by which the amceba feeds. When a 

 pseudopodium touches another Uving organism much 

 » The name amoeba is derived from Greek dftoi^ij, change. 



