28 



ANIMAL LIFE 



gating cells are of two distinctly different kinds. When 

 this kind of multiplication is to take place in the case of 

 Eudorina elegans, to choose a common species, some of 

 the cells of a colony divide into sixteen or thirty -two 



minute elongated cells, each 

 provided with two flagella. 

 These small cells escape 



FIG. 15. Eudorina elegans. A, a mature colony (from Nature); B, formation of 

 the two kinds of reproductive cells. 



from the envelope of the parent cell, remaining for some 

 time united in small bundles. Other cells of the colony 

 do not divide, but increase slightly in size and become 

 spherical in shape. When a bundle of the small cells 

 comes into contact with some of these large spherical 

 cells the bundle breaks up, and conjugation takes place 

 between the small flagellated free-swimming cells and the 

 large non-flagellate spherical cells. Each new cell formed 

 by the fusion of one of the small and one of the large cells 

 develops a cellulose wall and assumes a resting stage. 

 After a time from each of these resting spores a new colony 

 of sixteen or thirty-two cells is formed by direct, repeated 

 division. 



17. Volvox. Another interesting colonial protozoan is 

 Volvox. The large spherical colonies of Volvox globator 



