14G 



BIOLOGY OF THE PROTOZOA 



Radiolaria, in which they radiate out in all directions from a usually 

 spherical body (Fig. 78). 



Unlike nagella, the outer coating of an axopodium is not a smooth 

 periplast-like sheath, but consists of fluid protoplasm in which the 

 movements of granules out on one side and back on the other are 







c 



'#£<*SW59?*«Wi^. w ^» BO< s3(+*e*»*i,'3K#<"'.- . 





.. *"■■ t-- 1 *. ;J «-,--*• 



D 





Fig. 78. — Types of pseudopodia. ,4, B, Eruptive type of lobopodium; C, myxo- 

 podia type of Foraminifera ; D, axopodia type of Heliozoa. (After Calkins.) 



clearly discernible. In this manner the outer protoplasm is con- 

 tinually changing about the central axial filament, which alone is 

 constant or fixed. Upon prolonged irritation, or in preparation for 

 division or encystment, the axial filaments themselves, together 

 with the enveloping protoplasm, are withdrawn. 



Like flagella the axial filaments are formed as outgrowths from 



