PLATE I 



microphotographs reproduced by kind permission of 

 Dr. M. S. Navashin 



Fig, I. — Section of root-tip of Crepis dioscoridis, in = 8. Notice the 

 four chromosome types in all metaphases, and also various stages of 

 prophase and telophase of mitosis. Navashin-hsematoxylin sectioned 

 preparation, x 250. 



Fig. 2. — Outer metaphase plate at i o'clock in Fig. i. x 2300. 

 The chromosome lying right and left at 6 o'clock in the plate is from 

 another cell and is out of focus in this photograph. 



Fig. 3. — Metaphase of mitosis in root-tip of triploid Crepis capillaris 

 {2n = 3^; = 9). Of the three D chromosomes one has a large trabant 

 and two a small one. X 3000 {v. Text). 



