ONTOGENY 



15 



common, indeed in some it appears to be the normal method 

 of reproduction. 



Among the Protozoa this familiar distinction between germ 

 and soma cannot be drawn at all. In these simple forms the 



o o o o 



FIG. 11. Diagram illustrating the theory of Germinal Continuity. A, B, C, 

 represent successive generations; g, gamete (sperm cell) produced by another 

 organism; z, zygote. White circles indicate successive cell divisions within the 

 somatic tissues, the existence of which terminates with the organism of the given 

 generation. Solid black indicates the germ. Dotted circles indicate gametes 

 which may perish, or may unite with those of another organism. 



process of reproduction is not so directly associated with the 

 processes of gamete formation and fusion. Nearly all non- 

 colonial Protozoa, while in the so-called vegetative state, have 

 the power to reproduce by fission, so that the plasm of these 

 cells is both germinal and somatic in the Metazoan sense. It is 



