PROTOZOA 



25 



exhibit blunt, non-anastomosing pseudopodia, a clear ectosarc 

 with its contractile vacuole, and a granular entosarc containing 

 vacuoles and a nucleus. The fresh-water Difflugia (Fig. 4) fur- 

 nishes common examples of shells made up of particles of sand 



, (III,'//// 







>'H 



3.Squarr.rriu.!ir.i 4.M i I i I a 



Fig. 5. Various Foraminifera. a, aperture of shell ; f, food particles ; nu, nucleus; 



s/i, shell ; in 4 : a, the living animal; b, killed and stained. (From Biitschli's Pro- 

 tozoa and Claus' Zoology.) 



and other foreign bodies, such as the shells of diatoms, cemented 

 together. There is a good deal of diversity of shape in these 

 shells, which have one large opening through which the pseudo- 

 podia are protruded. The pseudopodia are like those of the 

 Amoeba. There are some Foraminifera, however, having shells 



