58 



ZOOLOGy 



complex. The protoplasm is distinctly divided into a central mass, 

 the medulla or endosarc (B, med.), in which the vacuoles are small, 



2.Nuclearia 



3.Clafhrulina 



Fig. 41. — Various forms of Heliozoa. 3a, the entire animal; 3&, the flagellula; c. vac. 

 contractile Tacuole ; g. gelatinous investment ; nu. nucleus psd. pseudopods ; sk. siliceous 

 skeleton ; sp. spicules. (From Butschli's Protozoa, after Schulze and Greeff.) 



and an outer layer, the cortex or ectosarc {cort.), in vsrhich they are 

 very large. There are numerous nuclei (nu.) and chromatophores 

 (chr.), the latter coloured green by chlorophyll, the characteristic 

 pigment of green plants. 



