THE CELL 15 



In certain cells protoplasm undergoes changes in shape. 

 This may well be studied in the white cells in the blood of 

 the frog or newt. Processes are pushed out, and these are 

 again withdrawn, or the whole cell may gradually follow the 

 process, and thus change its position. The processes are 

 called pseudopodia (false feet), and the mode of movement, 





FIG. 2. (a) White Cell from blood to show the centrosome and nucleus ; (6) Egg 

 Cell, dividing, shows reticulated structure of Protoplasm, two centrosomes 

 and nuclear fibres in mitosis (division of nucleus). 



from its resemblance to that seen in the amoeba, is called 

 amoeboid. 



The part played by reticulum and hyaloplasm in these 

 movements is not clearly understood. The pseudopodia are 

 at first free of reticulum ; but \vhether the hyaloplasm is 

 pressed out by contraction of the reticulum, or whether it 

 actively flows out, is not known. In some cells among the 



