256 The Structure of Protoplasm 



As the rhythmic contraction of the protoplasm is synchronized 

 with the streaming, it seems Hkely that one is the cause of the other, 

 from which the only constructive deduction to be made is that the 

 flow is the result of the rhythmic movement. 



Fig 3 The rhythmic contraction of two pseudopods of a shme mold Plas- 

 modium The top picture in each series is the fully expanded form and the bot- 

 tom pkture is the fully contracted form. The three left-hand pictures were 

 ph'to'^rlphed 20 and 2 J seconds apart; and the four right-hand P-^-es ^e- 

 ohotoeraphed 20 15, and 10 seconds apart. Note that m the left-hand pictures 

 the expaSed form at the top has a smooth contour, and the contracted form at 

 the bottom has a wrinkled contour. 



