THE PROBLEM 



41 



diagram shows the mode of descent in form reproducing 

 from two parents. The lines represent the lives of indi- 

 viduals (as in A diagram), or of germ cells (in the B 



A 



B 



FIG. 11. Diagram to show mode of descent in (A) unicellular animals reproducing agamic- 

 ally, and in (B) multi cellular animals reproducing by germ cells. For further explanation see 



text. (Modified from Jennings). 



diagram) beginning at the left and passing to the right. 

 In the A diagram, which represents uniparental reproduc- 

 tion by fission, the line of ancestry traced back from any 

 individual at the right is always single, and there is no 

 corpse to be found anywhere, each present body trans- 

 forming directly into the two bodies of the next generation. 



