AMEBOID MOVEMENT 145 



mechanism is one that attaches to the fundamental structure of 

 protoplasm rather than to the gross morphology. As a mathe- 

 matical question, however, the circles occurring in the path of an 

 ameba in low temperature may serve to connect up the flattened 

 spiral path of the ameba under optimum conditions with the 

 circular path often observed in man. 



The movement of the ameba thus becomes related to crawling 

 euglenas, Oscillatoria filaments, diatoms, and perhaps Gregari- 

 nidas, because of the movements of its surface layer; to leuco- 

 cytes, streaming protoplasm in the higher plant cells, etc., because 

 of its streaming endoplasm ; and to the locomotory movements of 

 all organisms because of the wavy character of its path, which 

 betrays the activity of an automatic regulating mechanism, a type 

 of which is held to be present in every moving organism. 



