190 BOTANICAL GAZETTE [MARCH 
EXPLANATION OF PLATES XIT AND XIII. 
The plates are reduced five-eighths in reproduction. The figures represent- 
ing entire cells and nuclei were studied with a Leitz no. 4 ocular and +g oil immer- 
sion objective; the others with a Zeiss no. 12 ocular and a Leitz +g oil immersion 
objective. 
PLATE XII. 
Fic. 1. Microsporocyte with chromatin network beginning to form the spirem. 
Fic. 2. Microsporocyte with delicate threads showing a single row of promi- 
nent chromatin granules. 
' Fic. 3. Single thread of the same. 
Fic. 4. Sporocytes beginning to separate. Nucleus with distinct arch 
contracted spirem in the so-called synapsis stage. 
Fic. 5. Single thread of the same showing a single row of chromatin granules. 
1G. 6. Sporocyte some time after the synapsis stage, showing prominent 
spirem with single row of chromatin granules. The free ends are cut. 
Ics. 7, 8. Single threads of the same. 
Fic. 9. Sporocyte with chromatin granules mostly double and flattened in 
appearance. 
Fic. 10. Somewhat later stage, showing the beginning of looping of spirem, 
and division of chromatin granules. One nucleolus beyond the nuclear cavity. 
Fics. 11-17. Single threads from the same stage, showing chromatin gran- 
ules still single, some with granules partly double, and others with typical double 
rows of granules. 
Fic. 18. Microsporocyte with loops nearly developed. 
Fic. 19. A single loop of the same stage. 
Fic. 20. Chromatin loops some time before separation; somewhat cut. 
Fic. 21. A single loop from the same stage. 
Fic. 22. Section of microsporocyte, showing chromatin loops near the time of 
separation. 
Fic. 23. A single loop from the same nucleus. 
Fic. 24. Microsporocyte, showing the twelve chromosomes. 
Fics. 25-37. Individual chromosomes, showing various types of loops and 
coils and their position on the spindle threads. 
PLATE XImI. 
Fic. 38. Mother star, showing position of chromosomes. Micronucleoli in 
the cytoplasm. 
Fics. 39-42. Chromosomes from mother-star stage, showing mode of sepa- 
ration of limbs of loops. 
Fic. 43. Microsporocyte with daughter stars. 
Fics. 44-50. Daughter chromosomes from the daughter star, showing char- 
acter of of the loops. 
Fic. 51. Daughter-star stage, with micronucleoli in the cytoplasm. 
