Physical Aspects of Protoplasmic Streaming 



223 



12 



10 



8 



6 



4 



2 







-2 



-4 



-6 



-8 



10 



12 



12 



10 



8 



6 



4 



2 







-2 



-4 



-6 



-8 



-10 



- 12 



Fig. 9 — continued. 



measure the period of the rhythm. It is evident that this method of 

 separating one rhythm from another is most practical, but one must 

 keep aware of the fact that the instants of reversal, where the motive 

 force is zero, have neither a significant meaning in rhythmic activity, 

 nor do they imply the savie phase of rhythm as manifested by the 

 graphs (all except Fig. 10). A reversal moment simply means a 

 momentary equilibrium of the intraplasmic forces. Pease (1940) is 

 also of the opinion that cessation of flow indicates a temporary equili- 

 brium state by acting as a "trigger mechanism." 



