AMCEBA 



65 



scope, the rest of the protoplasm is filled with granules 

 visible under the microscope and very variable in size 

 and nature. In the ectoplasm, but bulging into the 

 endoplasm, is situated a spherical space containing 

 liquid, and called the contractile vacuole, because it can 



B 



ani- 



Fig. I. — Amoeba proUus. Two successive views of the same individual. 

 The arrows show the direction of movement of the pseudopodia, 

 which in A are adhering to the glass slide, ps., pseudopodium ; 

 ect., ectoplasm (clear) ; end., endoplasm (granular) ; n, nucleus ; 

 C.V., contractile vacuole; d, diatoms (unicellular plants), which 

 have been taken into the endoplasm as food. The larger granules 

 are the undigested remains of food. After Cash, x about 320 

 (the organism is just visible to the naked eye). 



be observed to contract till it disappears completely 

 or almost completely, and then quickly appears again 

 in the same spot. The contractile vacuole is generally 

 regarded as excretory in function, i.e. as forcing out of 

 the body, whenit contracts, waste products of metabolism 

 including urea (a waste product containing nitrogen), 



5 



