458 EXPLANATION OF THE FIGURES. 



PLATE XVII. 



Figs. 1 — 8. Sphagnum cymbifolium, 



FIG. 



1. Longitudinal section of the terminal bud of the median shoot of a full- 



grown plant. The section has passed underneath the fifth leaf of the 

 left side of a lateral shoot, x 150. 



2. Longitudinal section of a young innovation, x 600. 



3. Terminal bud of a median shoot, detached and seen from the outside, 



X 600. 



4. Terminal bud of a median shoot with left-handed § phyllotaxis, seen from 



above, X 500. 



5. Terminal bud of a median shoot, detached by two transverse sections, of 



which one passed close down the apical point of the transverse cell, the 

 other through the stem close underneath the third-youngest leaf. All 

 the older leaves are cut through transversely. The leaves from a to /3 

 have a right-handed f arrangement ; from thence upwards the arrangement 

 is | and left-handed, x 500. 

 5*. Diagram. 



6. Young lateral bud, seen from the outside, x 500. 



7. Longitudinal section of a part of an innovation, taken at the point where the 



growth in thickness of the stem ends, x 500. 



8. Longitudinal section of one of the longitudinal moieties of a somewhat 



lower part of the same innovation, x 200. 



9. Sphagnum acutifolium. — Fragment of a longitudinal section of the circum- 



ference of the stem of the principal shoot from the lower boundary of 

 the region where lateral shoots are crowded together. The cells of the 

 interior of the stem have pitted walls. X 200. 

 9 6 . One of these pitted cells, x 600. 



PLATE XVIII. 



1. A young leaf of Sphagnum acutifolium, seen from the surface, x 400. 



2. Fragment of a somewhat more developed leaf of the same species, in whose 



cells the third division is beginning, X 400. 



3. Fragment of a leaf of Sphagnum cymbifolium in which the cells with, and 



those without chlorophyll are entirely differentiated. Several of the 

 former have divided by transverse septa, X 400. 



4. Fragment of a leaf of Sphagnum acutifolium in whose cells, which are 



devoid of chlorophyll, the formation of annular and spiral vessels has 

 commenced. Several of the latter cells have divided by longitudinal 

 or transverse septa, x 400. 



Figs. 5 — 13. Sphagnum acutifolium. 



5. Pro-embryo which has not yet developed any leafy shoots, x 10. 



6. A very young pro-embryo, X 200. 



