56 SEX AND HEREDITY 



flagellum, and that each is provided with a nucleus by 



FIG. 33. 



Diagram illustrating the life-history of Copromonas (after Dobell). 



The upper circle of figures (1-5) illustrates the process of reproduction, the lower 

 (5-12) that of syngamy. 



[The diagram includes two departures from the normal which are not alluded to 

 in the text, namely (a) a short-circuiting from 9-1 so as to omit encystment, and 

 (b) encystment without syngamy (i-n).] 



the original nucleus growing out into a dumb-bell shape 

 and then becoming nipped across into two. Each of the 



