THE PROTOZOA 



side to side, or through the continuous division of the cells in one plane 

 (Fig. 27). 



Many intermediate stages between simple binary division and spore- 

 formation show that the latter method of reproduction was probably 

 derived from the former. When simple division takes place within 



Fig. 27. Eiermocystis 

 polymorpha Leg., a cate- 

 noid colony of Gregarin- 

 ida. [WASIELEWSKY.] 



Fig. 28. Exogenous budding in Ephelota Butschliana Ishik. 



[FROM A PREPARATION.] 



The macronucleus (N) is continued into the four daughter- 

 cells, which appeared first as minute buds. 



a cyst, it not unfrequently happens that each of the daughter-cells 

 divides again, thus forming four daughter-cells within the cyst (some 

 Mastigophora and Sporozoa). Again, as many as eight or sixteen 

 may be formed in the same way, and from this it is not a great step 

 to the method of reproduction by spore-formation, where a great 

 number of young individuals are produced at one time. 



Another modification of simple division is the process of budding 



