AMEBOID MOVEMENT 



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Figure 43. The flagellate stage of a soil ameba, after Wilson, a, stained 

 preparation showing the two flagella arising from the blepharoplast, d, 

 which is connected with the caryosome, c, the central chromatin mass. 

 Much of the chromatin is deposited on the nuclear membrane, b, a draw- 

 ing from a live flagellate showing flagella, nucleus, c, and a vacuole. 



(which for the sake of reference will here be called flagellipodia, 

 Figure 44) whose pseudopodia stand about midway between 

 typical flagella and typical pseudopods in their activity. In its 

 general characteristics it stands near A. radiosa, but quite unlike 

 the stiff, static pseudopods which radiosa very frequently forms, 

 this ameba has usually five or more slender pseudopods of which 

 one or two or more are in slow flagellate motion. The distal third 

 or half of the pseudopod is in the shape of a corkscrew. The 

 free end of the pseudopod travels around in a circle (anti-clock- 

 wise in all instances observed), making one revolution in about 

 three seconds. If this motion were very rapid it would act like 

 a propeller and the ameba would swim through the water. The 

 part of the pseudopod back of the mobile portion is usually also 

 thrown into a spiral of gradually decreasing diameter until the 

 spirality disappears. This portion of the pseudopod is not mobile 

 in the same way that the distal portion is. Sometimes the whole 

 of a pseudopod is thrown into a spiral, all of the turns being of 

 equal size and only slightly motile. More than half of all the 



