Davis . — Cytological Studies on Oenothera . /. 
5^9 
Literature cited. 
Allen, C. E. (’05) : Nuclear division in the pollen mother-cells of Lilium canadense. Ann. Bot., 
xix, 1905, p. 189. 
Farmer, J. B., and Moore, J. E. S. (’05): On the meiotic phase (reduction division) in animals 
and plants. Quart. Joum. Micr. Sci., xlviii, 1905, p. 489. 
Gates, R. R. (’07) : Pollen development in hybrids of Oenothera lata x 0 . Lamarckiana, and its 
relation to mutation. Bot. Gaz., xliii, 1907, p. 81. 
— (’08) : A study of reduction in Oenothera rubrinervis. Bot. Gaz., xlvi, 1908, p. 1. 
Gr£goire, V. (’04) : La reduction numerique des chromosomes et les cineses de maturation. La 
Cellule, xxi, 1904, p. 297. 
* (’07) : La formation des gemini het^rotypiques dans les veg&aux. La Cellule, 
xxiv, 1907, p. 369. 
Lewis, I. M. (’08) : The behaviour of the chromosomes in Finns and Thuja. Ann. Bot., xxii, 
1908, p. 529. 
Mottier, D. M. (’03) : The behaviour of the chromosomes in the spore mother-cells of higher 
plants and embryo sac mother-cells. Bot. Gaz., xxxv, 1903, p. 250. 
(’07) : The development of the heterotypic chromosomes in pollen mother-cells. 
Ann. Bot., xxi, 1907, p. 309. 
Overton, J. B. (’05) : Ueber Reduktionsteilung in den Pollenmutterzellen einiger Dikotylen. Jahrb. 
wiss. Bot., xlii, p. 1905, 121. 
(’09) : On the organization of the nuclei in the pollen mother-cells of certain plants, 
with especial reference to the permanence of the chromosomes. Ann. Bot., xxiii, 1909, 
p. 19. 
Rosenberg, O. (’04) : Ueber die Individualitat der Chromosomen im Pflanzenreich. Flora, xciii, 
I 9°4> P-25I- 
(’05) : Zur Kenntnis der Reduktionsteilung in Pflanzen. Bot. Not., part i, 1905, 
pp. 1-24. 
Strasburger, E. (’04) : Ueber Reduktionsteilung. Sitzber. Kon.-Preuss. Akad. Wiss. Berlin, xviii, 
1904, p. 587. 
EXPLANATION OF FIGURES IN PLATES XLI AND XLIL 
Illustrating Prof. Davis’s paper on pollen development of Oenothera grandijlora. 
All figures were sketched with the aid of a camera lucida under the Zeiss apochromatic objective 
1.5 mm. (aper. 1-30) in combinatioi with the compensating ocular No. 12, giving a magnification of 
2,000 diameters. Figures 1-10 from sections 4 /x thick ; 1 1-18, 21, 28, 30, 32-42, 44, 46, 52-56 from 
sections 5 /x thick; 22, 24-27, 43,45, 47-51 from sections 7 /a thick; 19, 20, 23, 29, and 31 from 
sections 10 /x thick. Sections stained with iron-alum haematoxylin. 
PLATE XLI. 
Oenothera grandijlora. 
Fig. 1. Adjacent sections fron nucleus in young archesporium, showing chromatic bodies and 
large nucleolus. 
Fig. 2. Nucleus of archesporiim, reticulum formed preparatory to the development of the spirem. 
Fig. 3. Nucleus of archespcrium, early stages of the spirem showing the threads united at 
points. 
Fig. 4. Nucleus of archesponum spirem with granules (chromomeres ?) arranged in a single row. 
Fig. 5. Segmented spirem in archesporial nucleus resulting in fourteen sporophytic chromosomes. 
