234 



THE PROTOZOA 



nuclear apparatus varies in different forms, even in the same specie's, 

 as will be seen in the description of the reproductive processes. 



The marine Foraminifera, so far as they have been investigated, 

 show a well-marked alternation of generations in their life-history, 



St. 



FIG. 95. Polystometta crispa : decalcified specimens to s^ow the structure of the 

 two forms. A, The megalospheric type ; B, the microspherio type : 6, the 

 central chambers of the latter more highly magnified ; r., retral processes ; 

 st, communications between the chambers. From Lister. 



combined with dimorphism in the adult condition. An example it, 

 Polystometta, which has been investigated by Lister (285) and 



