SYSTEMATIC SURVEY. 



Fig. 46. — Optical section of a Radiolarian {Actinomma). 

 — After Haeckel. 



u.., Nucleus; £., wall of central capsule; c, siliceous shell within 

 nucleus ; c 1 . , middle shell within central capsule ; c 2 . , outer shell 

 in extra-capsular substance. Four radial spicules hold the 

 three spherical shells together. 



The others mostly resemble these types, but some, like Coca'dz'um, are 

 permanent cell -parasites. Gregarines are parasitic in many different 

 kinds of animals, including vertebrates. The Myxosporidia peculiarly 



Fig. 47. — A colonial flagellate Infusorian — Proterospongia 

 Haeckelii. — After Saville Kent. 



There are about 40 flagellate individuals, a. , nucleus ; b. , contractile 

 vacuole; c, amoeboid unit in gelatinous matrix; d., division 

 of an amceboid unit ; e., flagellate units with collars contracted ; 

 _/;, hyaline outer membranes ; g., unit forming spores. 



