37 ° Blackman. — On the Fertilization , Alternation of 
EXPLANATION OF PLATES 
Illustrating Mr. V. H. Blackman’s paper on the Uredineae. 
PLATE XXI. 
Figs. 1-13. Phragmidium violaceum, Wint. 
Fig. 1. Teleutospore, lying in water, showing general form and stalk with swollen base; the 
two upper cells have just begun to germinate, x 450. 
Fig. 2. Mature teleutospore, taken in autumn, in longitudinal section, showing the single 
nuclei and the structure of the wall and pits ; the uppermost cell is not cut exactly through the 
middle, so the nucleus and the apical peg of thickening are not shown, x 800. 
Fig. 3. Nucleus of the cell of a teleutospore, gathered in spring, which had been lying in water 
twelve hours, x 1900. 
Fig. 3 a. Similar nucleus, but showing a later stage with single spireme thread, x 1900. 
Fig. 4. Transverse section of cell of teleutospore, showing vacuolate nucleus ; wall structure not 
shown, x 1150. 
Fig. 4 a. Similar section, but showing abnormal state with two nuclei in the cell, x 1150. 
Fig. 5. Teleutospore in optical longitudinal section, showing development of long germ-tube; 
the apical cell has already germinated and is empty; the nuclei in the two lower cells appear as 
clear areas. Fresh preparation, x 450. 
Fig. 6. Germinating cell of teleutospore in transverse section, showing passage of tube through 
pit. x 970. 
Fig. 7. End of germ-tube (promycelium) with nucleus, x 600. 
Fig. 8. Promycelium divided into four cells, each of which has put out a germ-tube ; one 
nucleus has migrated into the tube, x 1150. 
Fig. 8 a. Promycelium with three sporidia and one cell not yet germinated, x 1150. 
Fig. 9. Mature promycelium from which two of the sporidia have fallen ; one of the two 
remaining is germinating in situ, x 950. 
Fig. 10. Primary sporidium in section with single nucleus, x 1350. 
Fig. 11. Secondary sporidium in section with two nuclei, x 1350. 
Fig. 12. Primary sporidium, still attached to sterigma, showing two nuclei, x 1350. 
Fig. 13. Secondary sporidium developed from primary and showing, apparently, four nuclei, 
x 1350- 
Figs. 14 - 35 . Gymnosporangium clavaidaeforme , Rees. 
Fig. 14. Mature two-celled teleutospore about to germinate, x 650. 
Fig. 15. Cell of similar teleutospore in transverse section, x 1350. 
Fig. 16. Germinated teleutospore, showing nucleus moving into tube on left, and nucleus 
dividing in middle of tube on right, x 620. 
Fig. 17. Early prophase of division of teleutospore nucleus in germ-tube (promycelium), showing 
centrosome and kinoplasm. x 1900. 
Fig. 18. Prophase showing chromatin collected, apparently as a single thread, towards one end 
of nucleus, x 1900. 
Fig. 19 a and b. Two consecutive sections through a germ-tube with dividing nucleus; the 
majority of the chromosomes are to be found in a, while b shows the very young spindle with 
centrosomes. x 1900. 
Fig. 20. Chromosomes collected irregularly round spindle ; one pole shows apparently two 
centrosomes. x 1900. 
Fig. 21. Chromosomes gathered towards centre of spindle, x 1900. 
Fig. 22. Similar stage to above, but spindle oblique in position, x 1900. 
Fig. 23. Chromosomes beginning to spread out on spindle; distinct radiations from upper pole, 
x 1900. 
Fig. 24. Chromosomes are shorter and show a tendency to arrange themselves in two rows 
and apparently to fuse together, x 1900. 
Fig. 25. Metaphase with shortened chromosomes stretched out on spindle, x 1900. 
