of ANNULAR VESSELS. 
inner surface (figs. 108, 7, 109, and 110). Sometimes the whole 
of the vessel presents this ringed appearance (figs. 109 and 110), 
while in other vessels we find two rings connected by one or 
more turns of a spiral, the two forms irregularly alternating with 
Fria. 108. Fic. 109. Fia. 110. Fia. 111. 
0 
J 
ti 
\\ 
iN 
‘ 
YK 
b 
\ 
S|] 
iy 
Fig. 108. Piece of an annular vessel from Zea Mays. 
h. The thin cell-wall; 7, the annular thickening of 
the cell-wall ; 7’, vertical section of one of the rings, 
showing, y, the inner substance, and, 7, the denser 
layer over the inner side of the ring projecting into 
the cavity of the cell. After Sachs.— Figs. 109, 
110, Annular vessels.——Fig. 111. Vessel showing a 
combination of rings and spiral fibres, 
each other (fig. 111). In size they vary from about ;3, to =}, 
of an inch in diameter. Annular vessels occur especially in 
the fibro-vascular bundles of the stems of soft, rapidly growing 
herbaceous plants among Dicotyledons, also in those of Mono- 
Fia. 112, 
ip ces tile! Bie. 115; 
Fig. 112. Reticulated vessel. Fig. 113. Prismatic scalariform vessels of 
a Fern. Fig. 114, Cylindrical scalariform vessels of the Vine.— Fig. 
115. Vessel showing a combination of spiral and reticulated fibres, and 
scalariform markings, 
cotyledons, and in those of some Cormophytes. In the latter 
they exist especially, and of a very regular character, in the 
Equisetacee (fig. 109). 
