CHAP. I. 
WOODY TISSUE. 
23 
acutely to each end, lying in bundles, and, like the cellular 
tissue, generally having no direct communication with each 
other, except by invisible pores. Slack states, that they are 
often met with open at their extremities; which probably 
arises either from the membrane being obliterated where it 
was applied to another fibre, or ruptured by the presence of 
an adjoining tube, as we sometimes find the conical extremity 
of another tube inserted into the aperture.” 
Many vegetable anatomists consider it a mere form of cel- 
lular tissue, in an elongated state. However true this may 
be in theory, woody tissue may be known by its toughness 
and extremely attenuated character. The distinction between 
cellular and woody tissue is particularly well seen in the 
long club-shaped aerial radicle of Rhizophora Candelaria. 
It there consists of large, very long, transparent tubes, lying 
imbedded in fine brownish granular matter, which is minute 
cellular tissue [jig. 7.) 
Usually it has no markings upon its 
surface, except occasionally a particle 
or two of greenish matter in its inside ; 
but sometimes it is covered with spots 
that have been mistaken for pores, and 
which give it a peculiar character (Plate 
II. fig. 3. 5. and *20.) ; and I have re- 
marked an instance, in Oncidium altis- 
simum, of its having tubercles on its 
surface. It often contains amylaceous 
granules in abundance. Generally, 
while cellular tissue is brittle, and has 
little or no cohesion, woody tissue has 
great tenacity and strength ; whence 
its capability of being manufactured 
into linen. Every thing prepared from flax, hemp, and the 
like, is composed of woody tissue ; but cotton, which is cellular 
tissue, bears no comparison as to strength, with either flax or 
hemp. 
Alphonse De Candolle gives the following as the result ob- 
tained by Labillardiere, as to the relative strength of different 
c 4 
