REMARKS ON THE NATURAL HISTORY OP COTTON. 173 
the outside of the plant, forming what is called its epidermis 
(fig. 23). It is in this epidermis that we find the little pores 
called stomates, which allow the fluids absorbed by the roots 
of plants to pass out. It is also upon this epidermis that we 
find growing those little projections which give a character to 
the surface of plants, as warts, hairs, prickles, and the like. In 
this respect the plant is like the animal, for it is from the 
epidermis of the animal that we find those appendages formed 
which we know by the name of scales, hairs (fig. 28), feathers, 
quills, and so forth. 
All these epidermal organs in the plant are composed of cel- 
lular tissue. The cells of these hairs are very delicate and 
feeble, and possess very much less power of resistance than 
the woody fibres. However long these hairs may be, they 
never possess strength enough for manufacturing purposes. 
They will not bear the twisting that is necessary to the pro- 
duction of a thread which can be woven. Many plants yield long 
hairs, as our own cotton-grass (fig. 19) and the silk-cotton (fig. 
20) tree of the West Indies ; but it is found impossible to twist 
them into a thread for the manufacture of textile fabrics. It is, 
then, very strange that we should find cotton belonging to this 
group of vegetable organs. Nevertheless, this is the fact. The 
cotton fibre is a hair : it does not, however, grow on the sur- 
face of the plant. Just as we find in animals, the epidermis 
continued into the internal cavities of the body from the outside, 
so we find the epidermis of plants continued into the interior of 
their fruit and on to the surface of the seeds. This is a very 
rare occurrence ; but in the case of the cotton-plant, it produces 
in the interior of the fruit, upon the surface of the seeds (fig. 16), 
a longer and stronger hair than any found upon the external 
surface of plants. But it is not the length nor the strength of 
the hair alone which gives to it the power it possesses of 
forming a thread when twisted. If examined under the micro- 
scope, the cotton-hair will be found apparently to consist of 
two delicate transparent tubes (fig. 15), — the one twisted round 
the other, so as to have the appearance of two pieces of cord 
wound round each other. If, however, the hair be examined in 
its young state, it will be found to be an untwisted cylindrical 
tube. It is during its growth that this change takes place. As 
the seeds and hairs grow, the capsules do not appear to expand 
with equal rapidity ; and, consequently, the hair is exposed to 
pressure on all sides. The result of this is, that the hair col- 
lapses in the middle, leaving a half-formed tube on each side. 
These uncollapsed portions of the hair give it the “ appearance,” 
says Bauer, “of a flat ribbon with a hem or border at each 
edge.” The hair does not, however, grow out straight, but, 
coming in contact with other hairs and the sides of the cap- 
