PLATE XV. 



Fig. 1. Two resting cells, showing chromatin granules, and nucleoli with 

 the surrounding clear space. 



Fig. 2. Cell beginning mitosis. Close spireme. Nucleoli without the 

 clear space. 



Fig. 3. A granular spireme. The nuclear membrane has disappeared 

 but the cytoplasm can still be distinguished from the nuclear 

 sap. 



Fig. 4. The chromatin granules are here arranged in rows. This cell has 

 its nuclear membrane yet and the nucleoli have not disap- 

 peared. 



Fig. 5. Polar view; spireme segmented to form the chromosomes, has a 

 longitudinal split, and is uniformly granular. Nuclear wall 

 just disappeared. Chromosomes looped to form U and J 

 shapes. 



Fig. 6. A little later than figure 5. The longitudinal split is very clearly 

 seen. 



Fig. 7. Late metaphase. Cytoplasm granular in places, may have been 

 slight plasmolysis in this cell. The spindle fibers are stained 

 very lightly here. 



Fig. 8. Metaphase. Spindle shows marked polarity; chromosomes some- 

 what indefinite. 



Fig. 9. Metaphase. Cytoplasm at the ends becoming vacuolated and at 

 the center slightly denser. An especially long chromosome 

 {m) is to be noted. 



Fig. 10. The cytoplasm of this cell was crushed; however, the chromo- 

 somes, which were undivided yet, show the longitudinal split 

 clearly. 



Fig. 11. Anaphase. Cytoplasm very granular in places (homogeneous 

 portion not shown). The spindle is well stained in this cell, 

 and the chromosomes have their characteristic bent shape. 



Fig. 12. Anaphase. Spindle not clear in this figure. The amount of 

 cytoplasm is small compared to the amount of chromatin here. 



