Studies on the Cytology of some Species of Taraxacum. 
467 
Tischlek, G. Über die Entwicklung des Pollens und der Tapetenzellen bei Ribes- 
Hybriden. Jahrb. f. wiss. Bot. Bd. XLII. 1906. 
Über die Entwicklung der Sexualorgane bei einem sterilen Bryonia-Bastard. Ber. 
d. Deutsch, bot. Gesellsch. Bd. XXIV. 1906. 
Zellstudien an sterilen Bastardpflanzen. Arch. f. Zellforsch. Bd. I. 1908. 
Untersuchungen über che Entwicklung des Bananen- Pollens I. Archiv f. Zell- 
forsch. Bd. V. 1910. 
Wixkler, H. Über Parthenogenesis bei Wickstroemia indica. Ann. du Jard. bot. 
de Buitenz. 2. Serie. V. 1906. 
Explanation of Figures, 
All figures were drawn witli the aid of the camera lucida, giving the magnification 
of nearly 1700 diameters, except Figs. 39 — 41, 55, and 73 — 77. 
PI. XXXVII, Fig. 1—41 relate teo T. plalycarpum-, PI. XXXVII, Fig. 42—52, 
and PI. XXXVIII, Fig. 53—77 relate to T. albidum. 
Plate XXXVII. 
Fig. 1. The nucleus of the pollen-mother-cell in presynaptic stage. 
Fig. 2. The same in synapsis. 
Fig. 3. The same in later stage. 
Figs. 4, 5. The same in spirem stage, showing the pairing of spirems in a few 
places. 
Fig. 6. The same, showing a single thick spirem in dolichonema stage. 
Fig. 7. The same, showing longitudinal Splitting of the spirem. 
Fig. 8. The same, in more advanced stage. 
Fig. 9. The same, showing more thickened spirem. Cross-segmentation already 
begun. 
Fig. 10. The same, showing long bent ehromosomes, which are twisted and 
form several irregulär rods in shape of X, Y, V, and O. 
Fig. 11. The same in more advanced stage, showing thicker and shorter paired 
ehromosomes. Figs. 12, 13. The same in later stage; some of the paired ehromosomes 
show hour-glass shape; eight ehromosomes. 
Fig. 14. Pollen-mother-cell. Its nucleus in diakinesis stage. 
Fig. 15. The same in early prophase of the heterotypic mitosis, showing the 
multipolar spindle. 
Fig. 16. The same, side-view of the heterotypic spindle in metaphase. 
Fig. 17. The same; polar view of the heterotypic spindle, showing eight cliro- 
mosomes. 
Fig. 18. The same in the anaphase of the same division. 
Fig. 19. The same, showing interkinesis stage between the first and second 
mitosis. 
Fig. 20. The same, showing the metaphase of the second mitosis. 
Fig. 21. The same, showing the anaphase of the same mitosis. 
Fig. 22. The same, showing the later telophase of the same mitosis. 
Fig. 23. Embryo-sac-mother-cell, showing the nucleus in synaptic stage. 
31 * 
