128 



COMPARATIVE ANATOMY 



ment produced by their extension and retraction is called 

 amoeboid movement. 



Careful observation of pseudopodial movement shows us 

 that the formation of a pseudopod is initiated by a slight 

 bulging of the hyaline edge of the cytoplasm ; the bulge 

 increases in size, and for a while the internal granular mass 

 is not affected. Then, rather suddenly, the granular mass 

 seems to flow into the hyaline process ; and, as it flows with an 



^ 



A 





9 \- 



( 









^i 



^C^ji 



^1 



D 



f--jt- - \ 



\ 



^r 



Fig. 28. 



A, Anifeba pyoteus; «, nucleus; c.?'. , contractile vacuole; _/5 a diatom enclosed in a 

 food vacuole. 5, C, D, three successive stages in the division of Aimsba 

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

 Atnceba. crystalligera, highly magnified, showing the central so-called nucleolus 

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

 highly magnified. (/4 after Leidy ; 5-7^ after Schaudinn.) 



active streaming movement of its granules, the hyaline process 

 spreads and extends, the internal granular stream keeping pace 

 with its extension, until a large lobe-like process is formed, as 

 large it may be as the whole of the remaining body of the 



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