Davis. — Nuclear Studies on Pellia. 
179 
shown in Figs. 3-22 and 33 was fixed by the weak formula of Flemming; that 
in Figs. 1, 2, 23-32, and 34-40 by 1 % chrom-acetic acid. Figs. 1-6, 8, 10, 14-16, 
18-20, 22-25, 29, 31-33, 35, 36, and 38-40 from sections 7-5 ja thick, and stained 
on the slide with safranin and gentian violet ; Figs. 7, 9, n-13, 17, 21, 26-28, 30, 
34, and 37 stained with iron-alum haematoxylin after the method of Heidenhain. 
PLATE X. 
Figures 1-21, from the spore-mother-cell. 
Fig. 1. Portion of spore-mother-cell, nucleus passing to the centre of convergence 
of the four lobes. 
Fig. 2. Nucleus taking position at the junction of the four lobes. 
Fig. 3. Synapsis occurring shortly before the first mitosis. Granular protoplasm 
(kinoplasm) lying next the nuclear membrane. 
Fig. 4. Spirem-thread, nuclear membrane faint, granular kinoplasm around the 
exterior. 
Fig. 5. Prophase: kinoplasm developing fibrillae' which are converging towards 
the four lobes of the cell, making the nucleus four-angled and giving an appearance 
suggestive of a four-poled spindle. 
Fig. 6. Prophase : fibrillae growing into the nuclear space ; chromosomes 
organizing. 
Fig. 7. Late prophase : nuclear membrane almost entirely dissolved, and nuclear 
space largely filled with developing fibrillae ; chromosomes with two rows of 
granules. 
Fig. 8. Surface view of nucleus in prophase, showing fibrillae extending into one 
of the lobes of the cell ; chromosomes below with two rows of granules. 
Fig. 9. Spindle at first mitosis showing broad poles ; one of them concave 
so that part of the spindle-fibres lies in one lobe and part in another. 
Fig. 10. First mitosis : daughter-chromosomes about to separate at the nuclear 
plate ; broad spindles with rounded poles, the fibrillae ending in granular kino- 
plasm. 
Fig. 11. Formation of cell-plate after first mitosis; spindle-fibres appearing 
to contract from the region of the daughter-nuclei ; no aster or radiations beside 
the daughter-nuclei. 
Fig. 12. Daughter- nuclei after first mitosis; chromosomes no longer present 
as organized bodies, but in their place a linin network with numerous granules ; 
several nucleoli ; nuclei lying in a bed of granular protoplasm free from plastids, 
similar to that which formerly surrounded the mother-nucleus as in Figs. 3 and 4. 
Fig. 13. Side view of spindle during second mitosis; slightly bent so that the 
poles enter the two lobes of the spore-mother-cell ; poles broad and ending in 
granular kinoplasm without further differentiation. 
Fig. 14. Anaphase of second mitosis, one spindle seen from the side, the other 
viewed obliquely from above ; chromosomes passing into an area of granular 
kinoplasm. 
Fig. 15. Nuclei in spores after the second mitosis; clear protoplasm at base 
of the spore derived from material associated with the two spindles. 
Fig. 16. Nucleus in spore shortly after the second mitosis ; chromosomes frag- 
mented into granules ; early appearance of a nucleolus. 
Fig. 17. Chromosomes at beginning of prophase ; granules arranged irregularly 
in two or more rows. 
N % 
