14 
HISTOLOGY OF VEGETABLES. 
and it is in this way that all the peculiar markings 
found in cells are formed, such as the rings, dots, and 
reticulations hereafter to be described. When the 
spiral cells are fully developed, as shown in Fig. 4, E, 
the fibre will separate from the membrane of the cell- 
wall, and its elasticity is such, that it ever tends to 
unroll itself, and in old elongated cells or vessels, it 
frequently ruptures the membrane, and becomes more 
or less straight. In this way the fibre may be obtained 
in an isolated condition. 
The bulbs of many of the lily tribe, and one species 
of squill from the Mediterranean, contain such immense 
numbers of spiral vessels, that the entire series of laminae 
of which they consist, appear to be composed of spiral 
fibres. These fibres are obtained in such abundance 
from some plants, that they are collected, bound into 
bundles, and used as a kind of slow match for lighting 
pipes and cigars. The elasticity of spiral fibre is very 
beautifully shown on the testa of the seeds of many 
plants, as the Collomia grandijlora , Salvia praten - 
sis , &c. When a minute portion of the testa is 
moistened with water, cells that were so closely adherent 
as not to be distinguished become soft, the spiral fibre 
released, as it were, from its close captivity, uncoils 
itself and pushes the cell- wall before it, and what was at 
first a brown shapeless object, becomes a mass of beau- 
tiful spiral cells ; a few of these cells from the Collomia 
are represented in Fig. 5. 
Fibre, like membrane, is frequently increased in 
