that in certain plants and trees the seeds or fruit are surrounded, in
the pods in which they develop, with a downy substance, and that the
cotton shrub belongs to this class of plants. A fibre picked out from
the mass of the downy substance referred to, and examined under the
microscope, is found to be a spirally twisted band; or better, an
irregular, more or less flattened and twisted tube (see Fig. 1). We know
it is a tube, because on taking a thin, narrow slice across a fibre and
examining the slice under the microscope, we can see the hole or
perforation up the centre, forming the axis of the tube (see Fig. 2).
Mr. H. de Mosenthal, in an extremely interesting and valuable paper (see
_J.S.C.I._,[1] 1904, vol. xxiii. p. 292), has recently shown that the
cuticle of the cotton fibre is extremely porous, having, in addition to
pores, what appear to be minute stomata, the latter being frequently
arranged in oblique rows, as if they led into oblique lateral channels.
A cotton fibre varies from 2·5 to 6 centimetres in length, and in
breadth from 0·017 to 0·05 millimetre. The characteristics mentioned
make it very easy to distinguish cotton from other vegetable or animal
fibres. For example, another vegetable fibre is flax, or linen, and this
has a very different appearance under the microscope (_see_ Fig. 3). It
has a bamboo-like, or jointed appearance; its tubes are not flattened,
nor are they twisted. Flax belongs to a class called the bast fibres, a
name given to certain fibres obtained from the inner bark of different
plants. Jute also is a bast fibre. The finer qualities of it look like
flax, but, as we shall see, it is not chemically identical with cotton,
as linen or flax is. Another vegetable fibre, termed "cotton-silk," from
its beautiful, lustrous, silky appearance, has excited some attention,
because it grows freely in the German colony called the Camaroons, and
also on the Gold Coast. This fibre, under the microscope, differs
entirely in appearance from both cotton and flax fibres. Its fibres
resemble straight and thin, smooth, transparent, almost glassy tubes,