THE RHIZOPODA 131 



ment produced by their extension and retraction is called 

 amoeboid movement. 



Careful observation of pseudopodial movement shows that 

 the formation of a pseudopod is initiated by a bulging of the 

 hyaline edge of the cytoplasm. The bulge increases in size 

 and for a while the internal granular endosarc is not affected. 

 Then, rather suddenly, the granular mass seems to flow into 

 the hyaline process. The granules flow forward, rapidly in 



>-:?5**TrV . .-^ 



- , -v * r" * ' ,>-.,- v ^\ ^ AA_r\ v --vv.lj>O^~ 



**rc 



Fig. 29. 



//, Ainirba />rotcus\ , nucleus; c.v., contractile vacuole;/, a diatom enclosed in a 

 food vacuole. 7>, C", />, three successive stages in the division of Atna~l<a 

 crystalligcra, showing the amitotic division of the nucleus. E, resting nucleus of 

 Amoeba crystalligera, highly magnified, showing the central so-called nucleolus 

 surrounded by an envelope of chromatin. F, dividing nucleus of the same species, 

 highly magnified. {A after LeidyJ B-F after Schaudinn.) 



the middle but usually more slowly at the sides, and as they 

 reach the extremity of the growing pseudopod they spread 

 out so that some of them approach its lateral borders. They 

 then stop while the central part of the stream moves on 



