

1909] SCHAFFNER— REDUCTION DIVISION IN AGAVE 213 



Fig. 23.— Somewhat later stage; chromosomes all crowded against the 

 nuclear wall with a clear cavity in the center. 



Figs. 24, 25. — Nuclei showing indefinite chromosomes. 



Fig. 26. — Section of nucleus showing parts of twelve chromosomes. 



Figs. 27, 28. — Nuclei showing twelve chromosomes of diverse shapes and 



sizes. 



Fig. 29. — Section of nucleus showing the three ring-chromosomes. 



PLA TE XIII 



9 



Figs. 30, 31. — Nuclei with twelve chromosomes, showing the beginning of the 

 appearance of delicate connecting fibers. 



Fig. 31a. — Fragmenting nucleoli taken from same stages as fig. 31. 



Figs. 32-36.— Microsporocytes showing synizesis after the formation of the 

 chromosomes; also connecting fibers between the chromosomes. 



Fig. 37.— Nucleus contracted away from the incipient spindle; prominent 

 connecting fibers between the chromosomes. 



Fig. 38. — The same, but with less synizesis of the nucleus. 



Fig. 39.— Nucleus showing distinctly the incipient spindle. 



Fig. 40.— Incept of spindle showing as two caps on opposite sides of the 

 nucleus. 



Fig. 41.— Nucleus showing incipient spindle. 



Fig. 42.— Nucleus with incept of spindle and aster at one pole. 



Fig. 43.— Nucleus showing young spindle and connecting fibers between the 

 chromosomes. 



Figs. 44-46.— Further successive stages in the development of the spindle. 



Fig. 47.— Chromosomes, connected by fibers, being drawn into the equatorial 

 Plane; spindle with aster showing at one pole. 



Fig. 48.— Distorted spindle. 



Fig. 49.— Spindle showing the two poles. 



Figs. 50-59. — Successive stages in the development of the spindle and the 

 Siting of the chromosomes into the equatorial plane. Fig*. 57' 59 on P late XIV - 



PLA TE XI V 



fLATK XIV 



Fig. 60.— Spindle, showing asters and centrosomes; the chromosomes nearly 

 m ^e equatorial plane. 



ig. 61.— Mother star with aster at the poles. 

 *igs. 61a, 616, 61c, 6id y 6m.- Chromosomes on the spindle fibers, showing 

 at the close d loop extends outward. 

 Hg. 62.— a chromosome from the mother star of the second division with the 

 ^ ends of the V projecting outward. 



feu 1 63 "~ Polar view of chromosomes, showing the three ring-chromosomes; 

 five f g chrom osomes, two of which lie side by side and are very large; and 



F ma r chr <>niosomes of various shapes and sizes. 

 thre f 64 :~ Dia g° nal section of mother star, showing the twelve chromosomes, 

 °f which occupy a central position; also the four long chromosomes. 



