Azolla filiculoides, Lam. 
i85 
EXPLANATION OF FIGURES IN PLATES 
VII, VIII, AND IX. 
Illustrating Professor Campbell’s paper on Azolla filiculoides, Lam. 
The Figures are all drawn from microtome-sections, except Figs. 27 and 75. 
PLATE VII. 
Fig. 1. A horizontal section through the growing-point of a branch of Azolla 
filiculoides. x 350. Owing to the upward curvature of the apex, the apical 
cell was not cut through in this section. Z, leaves ; Kn , young branch ; h, hair ; 
sp, young macrosporangium. 
Fig. 2. A horizontal section through the apex of a similar branch. x6oo. 
Figs. 3 and 4. Vertical longitudinal sections through the apex of the stem. 
x6oo. x, the apical cell; n, Anabaena- filaments; b, a hair; r, mother-cell 
of a root. 
Fig. 5. Three successive transverse sections just behind the apex. x6oo. 
m, the median wall ; Z, mother-cell of a leaf. 
Fig. 6. An older transverse section. The leaf already shows the two lobes, 
Z and Z\ 
Fig. 7. Single lobe of a young sterile leaf, x 600. 
Fig. 8. Fertile segment of a leaf, showing two very young sporocarp-rudiments. 
X 600. The apical cells have the nuclei indicated. 
Fig. 9. Young female sporocarp. The archesporium is already differentiated. 
id, indusium. x6oo. 
Figs. 10 and 11. Older stages of the same. x6oo. t, the first tapetal cell. 
Fig. 12. Transverse section of a stage somewhat older than in Fig. 11. x6oo. 
t, tapetum ; w, wall. 
Figs. 13—16. Older stages of the sporocarp. X350. The nuclei of the tapetal 
cells are indicated, the sporogenous cells are shaded, n, A}iabaena-h\a.mQn\.s 
that have crept into the open indusium. sp (Fig. 16), rudimentary sporangium. 
In Fig. 16, the isolation of the spore-mother- cells has begun. 
Fig. 17. A single spore-mother-cell, just before its separation from the others, 
x 1500. 
Fig. 18. Two spore-mother-cells, showing the beginning of the first division. 
The nuclear spindle is well marked ; a, from the pole ; b, from the side, x 750. 
Fig. 19. Two later stages. In a, the first division is nearly completed. In b, 
the second division is complete, and the division into the four spores has begun. 
x 750- 
Fig. 20. The four spores lying within the mother-cell, x 750. 
Fig. 21. Young macrospore surrounded by the nucleated protoplasm of the 
disintegrated tapetum. X750. 
