98 
HISTOLOGY OF VEGETABLES. 
Fig. 85, where in a single bundle, 
the outermost vessel on one side is 
dotted, and that on the other annu- 
lar ; between these, spiral vessels occur, 
with their spires more and more widely 
separated. This state of things may 
be also observed in the Lettuce , in 
the root of which plant, bundles of 
vessels are frequently seen in various 
stages of development at one and the same time. 
In some plants, and especially in the Canna bicolor , 
the spiral vessels are remarkable for the occurrence 
of longitudinal as well as spiral fibres. In Fig. 86, /i, 
is represented what might be taken at first sight for 
an ordinary spiral vessel of large size, but, if carefully 
examined, a series of minute longitudinal fibres will also 
be observed, and when such a vessel is unrolled, the 
broken ends of these fibres, as represented by c h e, 
will be found projecting above and below the spirals. 
In many cases, both the longitudinal and spiral fibres 
are of the same size and equi-distant. The vessel 
represented in Fig. 86, is covered with square 
markings, but retains its capability of unrolling. In 
another specimen, Fig. 86, /, from the same plant, 
the longitudinal fibres, although of the same size, are 
wider apart than the spirals; the vessel in this case 
presents markings which are true parallelograms, not 
squares. 
These remarkable vessels have amongst them others, 
FIG. 85 . 
A bundle of ves- 
sels from the stem 
of a Balsam. 
