62 
Farmer —On Isoetes lacustris, L. 
EXPLANATION OF FIGURES IN PLATES 
V AND VI. 
Illustrating Mr. Farmer’s paper on Isoetes lacustris. 
(N.B. — Figures Nos. 26 and 27 refer to I. velata.) 
PLATE V. 
Figs. 1, 2, 3. Sections through the root of the embryo. The lines through the 
small diagrams accompanying Figures 1 and 2 represent the direction of the section, 
which lies in the plane of the paper in Fig. 2. 
Fig. 4. Transverse section through the vascular bundle at the base of an old 
root. 
Figs. 5, 6, 7, 8. Transverse sections through young root-tips at successively 
greater distances from the actual apex. 
Fig. 9. Longitudinal section through young root apex. P— plerome. 
Fig. 10. Longitudinal section through another root apex. P= plerome, E ~ der- 
matogen. 
Figs. 11, 12. Transverse sections of stem-apex. Fig. 11 shows superficies; xxxx 
the meristem ; L a leaf rudiment. Fig. 12 from the same stem, but the plane of 
the section lies deeper than in Fig. 11. 
Figs. 13, 14. Longitudinal section of stem with young leaf. 
Fig. 15. Vascular bundle of leaf. x = xylem, Ph — phloem, s = sheathing cells of 
the xylem. 
Fig. 16. Longitudinal section through half a leaf. E = epidermis. The large 
cells on the left abut on the vascular bundle which is not shown. 
Figs. 17, 18. Stages in germination of macrospore. 
Fig. 19. Section through a spore cut parallel to the base. 
Figs. 20, 21. Archegonia. 
PLATE VI. 
Fig. 22. Transverse section through young leaf, L. This is enclosed in the 
ligule {Li) of the next oldest leaf, and this again by that of a still older one. 
x = tracheid. 
Fig. 23. Transverse section of leaf, x = tracheid. 
Fig. 24. Section through a spore, n — nucleus, k — nucleolus, j = starch. 
Fig. 25. Another spore, with well-marked nucleus and nucleoli. 
Fig. 26. Transverse section of stem of Isoetes velata . 
Fig. 27. Longitudinal section of the same. 
Fig. 28. Transverse section of root of Isoetes lacustris just beneath the apex. 
Fig. 29. Transverse section through the same root, separated by the thickness of 
one section. 
Fig. 30. Longitudinal section through root. P— plerome. 
