EXPLANATION OF THE FIGURES. 471 



FIG. 



6. Lateral view of a terminal bud of the same species laid bare by two parallel 



lomritudinal sections, X 30. 



7. Terminal bud of the same Equisetum exposed by thin parallel sections 



perpendicular to the axis of the stem. The youngest and the second 

 youngest leaf are uninjured ; the rest are cut transversely. X 20. 



8. Portion of a very young leaf of Equisetum limosum exposed by transverse 



section through the end of the stem, seen from above, x 300. 



9. Lateral view of two tips of a somewhat older leaf; the one to the right is 



about to fork, x 300. 



10. Mother-cell of one of the whorled adventitious shoots of Equisetum limosum 



exposed by two parallel longitudinal sections through the young stem-end. 

 X 300. 



11. Longitudinal section of a similar shoot in a somewhat later stage of de- 



velopment, x 300. 



12. Longitudinal section of a portion of an older internode, with a fragment of 



the leaves belonging to it. The section has laid open the cavity of the 

 base of the leaf, in which an adventitious bud is concealed. X 60. 



13. Part of a longitudinal section of a young internode of Equisetum pratense. 



In the cells of one longitudinal row annular vessels are formed. The 

 transverse septa of these cells are still present. X 300. 



PLATE XXXVI. 



1. Left side of a delicate longitudinal section of the apex of a growing 



delicate shoot of Equisetum variegatum, X 300. 



2. A portion of the seventh iuternode (reckoning downwards from the apex), 



from the same longitudinal section. 



3. Longitudinal section of the rudiment of the fruit of Equisetum limosum at 



the beginning of April, x 30. 



4. 5. Longitudinal section of the youngest sporangium-receptacle from the 



same specimen, X 200. 

 0. Half-developed fruit (at the end of October) of Equisetum arvense, in 



longitudinal section, X 50. 

 7, 8, 9. Stages of development of the sporangia of the same species, all in 



longitudinal section, X 300. 



10. Transverse section of a young sporangium of the same species, x 300. 



11. Group of young primary mother-cells of the spores of Equisetum variegatum; 



two of them are about to divide, X 300. 



12. Pour spore-mother-cells of Eq. limosum adherent to one another, more 



developed, X 300. 



13. Half of a young receptacle, with sporangium of the same species, x 150. 



PLATE XXXVII. 



Figs. 1 18, 21, 24. Equisetum limosum. 



1. Tree spore-mother-cell, x 400. 



2. Spore-mother-cell, whose primary central nucleus has dissolved, x 300. 



