1 56 Wilson — On Spore Formation and Nuclear 
14 . Gregoire, V. : La formation des gemini h^terotypiques dans les vegetaux. La Cellule, t. xxiv, 
1907 . P* 371 - 
15 . Gregoire, V. : La structure de l’element chromosomique dans les cellules v^getales. La 
Cellule, t. xxxiii, 1906, p. 390. 
16 . Holferty, G. M. : The Archegonium of Mnium cuspidatum . Bot. Gaz., vol. xxxvii, 1904* 
p. 106. 
17 . Humphrey, J. E. : On some Constituents of the Cell. Annals of Botany, vol. ix, 1895, p. 561. 
18 . Ikeno, S. : Blepharoplasten im Pflanzenreich. Biol. Centralbl., Bd. xxiv, 1904, p. 211. 
19 . . : Die Spermatogenese von Marchantia polymorpha. Beihefte z. Bot. Centralbl., 
Bd. xv, 1903, p. 65. 
20 . Leeuwen-Reijnvaan, J. und W. van : On a Double Reduction in the Number of Chromo- 
somes during the Formation of the Sexual Cells, and on a Subsequent Double Fertilization, 
in some species of Polytrichum. Koninklijke Akademie te Amsterdam. Proc. of Meeting, 
Nov. 30, 1907. 
21 . : Uber eine zweifache Reduktion bei der Bildung der 
Geschlechtszellen und darauf folgende Befruchtung mittels zwei Spermatozoiden und 
uber die Individualist der Chromosomen bei einigen Polytrichum- Arten. Recueil des 
Travaux botaniques Neerlandais, vol. iv, 1907. 
22 . Nichols, M. L. : The Development of the Pollen of Sarracenia. Bot. Gaz., vol. xlv, 1908, p. 31. 
23 . Strasburger, E. : Typische und allotypische Kernteilung. Jahrb. fur wiss. Bot., Bd. xlii, 
1905, p. 1. 
24 . Wilson, M. : Preliminary Note on Nuclear Division in Mnium hornum. Annals of Botany, 
vol. xxii, 1908, p. 328. 
explanations of figures IN PLATES X AND XI. 
Illustrating Mr. Wilson’s Paper on Mnium hornum. 
Figs. 1-13 illustrate somatic divisions, Figs. 14-22 the reduction divisions. 
(All the figures were drawn with the camera lucida under 2 mm. Horn. Imm. Zeiss with 
Comp. Oc. 12 or 18, giving magnification of 1500 and 2250 respectively.) 
Fig. 1. Cell with resting nucleus from single-celled archesporium. x 1500. 
Fig. 2. Cell with resting nucleus showing differentiation in cytoplasm, x 1500. 
Fig* 3 * Nucleus in early prophase, x 1500. 
Fig. 4. Band-like chromatin areas differentiated. X 1500. 
Fig. 5. Further contraction of chromatin areas, x 1500. 
Fig. 6. Spireme, x 1500. 
Fig. 7. Division of spireme to form chromosomes, x 1500. 
Fig. 8. Chromosomes on equatorial plate, x 1500. 
Fig. 9. Polar view of metaphase, x 1500. 
Figs. 10 and 11. Diasters, x 1500. 
Fig. 12. Telophase showing formation of nucleoli and new cell wall, x 1500. 
Fig. 13. Almost resting daughter-nuclei, x 1500. 
Fig. 14. Resting nucleus from spore-mother-cell, x 1500. 
Fig. 15. Resting nucleus showing budding of nucleolus, x 1500. 
Fig. 16. Nucleus with more granular reticulum showing constriction of body from nucleolus. 
X 1500. 
Fig. 17. Spore-mother-cell with nucleus in very early prophase, x 1500. 
