2l6 



THE PROTOZOA 



of conjugation is somewhat modified in certain Bodos of the group 

 Heteromastigida, where, after a period of binary fission, as in Cerco- 

 monas, the individuals become amoeboid, two or three fusing while in 



Fig. 117. — Conjugation in Tetramitus rostratus Perty. [STEIN.] 

 A, B. Individuals from the front and side. C. Amoeboid form. D. Conjugation of amoeboid 

 forms. B. Cyst, p, G, H. Development of the spores. 



this condition to form a common mass. After a resting period, the 

 encysted mass breaks up into an immense number of small individuals, 

 or spores, differing from those in Cercomonas, in that each one is 

 similar to the parent organism. This union, however, appears to be 

 purely facultative, for the same process of encystment and spore- 



