235 
Vascular System of the Genus Equisetum. 
Fig. 2. a and b. External view of lower parts of two sporelings, showing the position of the 
secondary axis. In b it appears much nearer to the root than in a. The prothallus has been 
removed, x 68. From drawings by Dr. S. Chandler. 
Fig. 3. An abnormal annulus of E. palustre showing the development of sporangia. Seen from 
above. 
Fig. 4. Longitudinal view of basal region of very young sporeling from a cleared preparation. 
The cortical tissues have been omitted. The. endodermis is conspicuous owing to the cuticularized 
band staining deeply with ammoniacal fuchsin. Note the difference in level of the two leaf-traces, 
x 180. 
Fig. 5. Transverse section of basal region of young sporeling, showing the central cylinder 
only. Note the curious appearance of the reticulate tracheides in sectiou. x 320. 
Fig. 6. Tracheides from the basal region of the same sporeling more highly magnified, x 640. 
PLATE VII. 
Fig. 1. A node and part of an internode of a sporeling of E. arvense from a cleared preparation. 
Note the first development of metaxylem (m). x 425. 
Fig. 2. Base of a sporeling of E. arvense , showing two aerial axes and the early stages in the 
formation of the third, x 63. 
F = foot. S L , s 2 = primary and secondary axes. 
B = bud which will form third axis. 
X =* vascular supply for B. 
o = ochreola. 
L = first leaf-whorl. 
IJ = leaf- trace. 
R x = xylem strand of first root. 
R 2 = xylem strand of second root. 
Fig. 3. A young node and internode near the apex of a sporeling of E. arvense before the 
nodal tracheides have linked up the internodal xylem. From a cleared preparation, x 425. 
Fig. 4. Four internodes of a bud of E. 7 naximum , showing^the early differentiation of internodal 
xylem. Note that the strict alternation of the strands is departed from by the introduction of an 
extra member in one whorl. From a cleared preparation. 
Fig* 5 - The vascular supply of half a cone of E . palustre. From a cleared preparation, x 12. 
Fig. 6. The vascular arrangement of the cone of E. limosum : From a cleared prepara- 
tion. x 12. 
