PROTOZOA 



159 



found in the sexual cells in the Metazoa or many-celled animals, 

 and illustrates heterogamy (see 101). Consult Figs. 7, 69, 73. 



200. History. The existence of the Protozoa was prac- 

 tically unknown until the compound microscope came into use. 



FIG. 72. 



FIG. 72, Eudorina. A colony of 16 flagellate cells imbedded in a gelatinous matrix. 



FIG. 73- 



FIG. 73. Eudorina. The development of reproductive bodies within the colony from the 

 ordinary vegetative cells (). /, a mass of female cells; m, a mass of male or motile cells;/', a single 

 female cell surrounded by male cells (mO; w, the boundary of the original colony. 



Questions on figures 72 and 73. What suggests that this is a colony rather 

 than an individual? What suggests the reverse? Compare accounts in other 

 texts to test your conclusions. What degree of differentiation is shown among the 

 cells? 



