io8 AMEBOID MOVEMENT 



ameboid streaming, if it is a surface tension phenomenon as seems 

 to be the case, depends upon the surface energy of the interfaces 

 of the emulsoid colloidal system in the endoplasm. It has already 

 been seen that those cases of locomotion due in large measure 

 to the power of contractility in the ectoplasm (Difflugia, Forami- 

 nifera) are also explained as being due to a change of phase 

 in the colloidal system, which is in itself a surface tension effect. 

 It appears therefore that all the lower organisms that move, ex- 

 cepting flagellated or ciliated organisms (of whose motor mechan- 

 ism we have no detailed knowledge), depend upon surface energy 

 as the source of the energy of movement. 



