PROTOZOA 



13 



in different organisms — in Amoeba, a stratum which, save at its 

 surface, is only unlike that below it in not containing granules; in 

 various planktonic protozoa (Figs. 32, 33) a highly vacuolated layer 



Fig. 6. Shells of foraminifera. A, Rhabdarrmmia abyssorum, x 4-5. B, Nodo- 

 saria hispida, x 18. C, Globigerina bulloides, x 55. After various authors. 



whose low specific gravity confers buoyancy; in the Ciliophora and 

 many flagellates and sporozoa a stout pellicle with an underlying layer, 

 the cortex, which is said to be stiffer than the internal protoplasm 

 {endoplasm) and may exhibit differentiations of various kinds. 



