PLATE 44 



The drawings are semi-diagrammatic. Tliey were made witli a camera lucida, 

 using a 4 mm. dry objective and a number 18 Zeiss compensating ocular. Tlie 

 chromosomes and nuclei are simply outlined, the plastids at the upper focus 

 are in gray wash with a stippled margin, while the lower ones are left Avhite. 

 The drawings show the position of the plastids at successive stages in micro- 

 sporogenesis. 



1. Polar view of late first prophase showing 12 pairs of chromosomes, one of 

 whicli is about twice the size of the others. 



2. Lateral view of same stage showing that the spindle area is largely free 

 of plastids. Most of the plastids are near the poles. 



3. Lateral view of late anaphase showing movement of plastids from poles 

 toward equator of cell. 



4. Late telophase. The plastids are now arranged in a double ring at the 

 equator. 



5. Late second prophase. The plastids are so closely massed that ring 

 formation cannot be distinguished. 



6. Late second anaphase. The ring of plastids is being distorted. 



7. Second telophase. The ring is now breaking into four segments, one group 

 lying about the inner face of each of the four nuclei. 



8. Early cell division. The dotted lines show cell plate. The outer wall is 

 pushing inward between each of the four nuclei. 



9. Cell division completed. 



[248] 



