Heredity in Protozoa 



603 



In general then it must be realized that the parts of the body 

 of the infusorian do not have a permanent definite relation to the 

 form or structure. A portion of substance that is anterior in one 

 generation is posterior or median in another. Thus definite 



Fig. 7 Diagram showing the usual regular changes in form and alternations in position of the spine 

 through four generations. The numbers at the left indicate the generations, a younger and an older 

 stage being shown in each generation (save the fourth), a is the anterior product of fission, p the pos- 

 terior one. In generations i and 3 the spine is on the anterior half of the posterior daughter cell; in 

 generations 2 and 4 it is on the posterior half of the anterior daughter cell. 



