15. 
16. 
17. 
18. 
Fig. 
SCALES OF AQUATIC MONOCOTYLEDONS. 237 
Sortms-Laupacu, H.— Bot. Zeitung, 1892, p. 110. 
Bowzn, F. O.—Studies in the Morphology of Spore-pro- 
ducing Members. Phil. Trans. vol. 185 B. (1894) pp. 473- 
572, tt. 42-52. 
RENDLE, A. B.—A Systematic Revision of the Genus Naas. 
Trans. Linn. Soe. ser. i, Bot. v. (1899) pp. 379-436, 
tt. 39-42. 
Id.—Supplementary Notes. Tb. (1900) pp. 437—444. 
EXPLANATION OF THE PLATES. 
PLATE 5. 
l. Transverse section of a young shoot of Alisma Plantago, showing 
numerous axillary scales between the leaves. X 30. 
2. “ Ball-and-socket" association of adjacent scales in Zostera marina. 
x 350. 
3. Longitudinal section of the apex of Alisma Plantago, showing an early 
stage in the development of the leaf and of the axillary scale of the 
subjacent leaf (to the left); the earliest stage in the development of 
the scales is indicated by the cell with shaded nucleus to the right of 
the young leaf. x 550. 
4. Longitudinal section of the base of the scale in Zostera marina, X 550. 
5. Longitudinal section of the base of the scale in Sagittaria sagittifolia. 
x 350. 
6. Longitudinal section of the base of the scale in Vallisneria spiralis. 
x 550. 
PLATE 6. 
Figs. 7 & 8. Two stages in the development of the scale in Potamogeton per- 
foliatus. x 550. 
Fig. 9. Older stage of the same, showing the entrance of a procambial strand 
into the leaf-base. x 550. 
10. Transverse section of the apex of Ruppia sp. The anatomical features 
of the axillary scales only are indicated. Xx 75. 
11. Partially cutinized cells (with dark outlines) of the base of the scale of 
Hydrocharis Morsus-rane. Xx 550. 
19. Longitudinal section of the leaf-base of Alisma Plantago. The wing- 
like expansion of the leaf is shown at a; the base of an older leaf 
atb; the axillary scale is figured in the centre as arising from a 
single cell-row (cells shaded). Xx 550. 
13. Longitudinal section of the base of the leaf and scale of Stratiotes 
aloides. X 350. 
14. A small scale of Alisma Plantago on face-view. X 75. 
15. Base of the scale of Sagittaria sagittifolia on face-view. x 350. 
16. A small scale of Alisma Plantago in transverse section. x 550. 
17. Longitudinal section of the base of the leaf of Alisma ranunculoides, 
showing the concentric origin of scales. X 550. 
