EXPLANATION OF THE FIGURES. 467 



FIG. 



4. Longitudinal section of the end of the bud of the principal axis of the 



same, X 400. 



5. A further developed germ-plant shown in a longitudinal section through 



the median lines of the first two fronds. The first and fourth adventi- 

 tious roots have been cut by the section. 



6. A more developed germ-plant shown in a longitudinal section at right 



angles to the former one, the section passing through the second and 

 third adventitious root. 



7. Transverse section of the older portion of the axis of a seedling of a 



month old, X 30. 



8. 9. Transverse section of the same nearer the apex. 



9*. The same at another neighbouring point of the same axis, x 5. 

 10, 11. Seedling of a year old. Natural size. 

 12, 13. Transverse section of the stem of the same, taken near the apex, x 5. 



14. Transverse section of the third frond of a germ-plant, x 10. 



15. The end of a vigorous shoot in November. Natural size. Adjoining the 



end of the stem is seen the frond destined for development in the follow- 

 ing spring. More to the left is seen the lower part of the frond of the 

 current year, whose lamina has already opened. 



16. Forking stem-end, seen in a section through the longitudinal ridges. The 



sheath of vascular bundles of the middle of the stem is laid bare by 

 the section. Twice the natural size. 



PLATE XXX. 



PTEKIS AQUIL1NA. 



J } ", *. «■ A similar shoot in the spring, peeled as far as the cortical vascular 

 bundle, in order to show its course. Seen from the left, from the right, 

 and from above. Natural size. 



1. d ' e - The principal vascular bundles of the shoot, with their ramifications 



to the frond of the previous year. 



2. Transverse section of a stem at the place of insertion of a frond. Natural 



size. 



3. Transverse section of a stem, x 3. 



4. Longitudinal section of the terminal portion of the apex of a frondless stem 



of a very old plant, X 15. 



5. Apex of a stem bearing a young frond, with the rudiment of an adventitious 



bud, seen from above. Natural size. 



6. Erond destined for development in the following year, as it appears late in 



autumn, after the removal of the scales ; seen in front. Natural size. 

 6". The rudiment of the lamina of this frond, x 15. 



7. 8, 9. Transverse sections of a stipes — fig. 7 close to the stem, figs. 8 and 



9 somewhat higher up, x 3. 



10. Transverse section of a portion of the lower principal vascular bundle of the 

 stem-bud, one and a half line backwards from the apex, x 150. 



