LYMPHATIC AND GLANDULAR HAIRS. 67 
The ordinary hairs above described are either empty, or they 
contain fluid of a watery nature, which may be colourless or 
coloured. Such have been therefore termed by some botanists 
lymphatic hairs, to distinguish them from other hair-like appen- 
dages which are filled with special secretions, and hence have 
been called glandular hairs. The latter will be again alluded to 
under glands, to which variety of epidermal appendage they 
properly belong. 
Hairs occur upon various parts of plants, and, according to 
their abundance and nature, they give varying appearances to 
their surfaces, all of which are distinguished in practical Botany 
by special names. The more common position of hairs is upon 
HIG. 157. Rie. 158; Fria. 159. 
Le 
: 7 SS 
Fig. 157. a, Cotton. 6, Fiax fibres (liber- 
cells)——F'ig. 158. Pistil of the Bell- 
flower (Campanula), with its style 
y covered with collecting hairs. Fig. 
159. Magnified representation of two of 
the collecting hairs of the Bell-flower. 
a, The hair in its normal position. b. The 
hair with the upper part partially drawn 
within its lower. From Schleiden. 
the leaves, stem, and young branches, but they may also be 
found on the flower-stalks, bracts, parts of the flower, the fruit, 
and the seed. The substance called cowhage consists of the 
hairs covering the legumes of Mucuna pruriens ; while cotton 
is the hair covering the seeds of the species of Gossypium. 
Cotton may be readily distinguished under the microscope 
from the liber-cells already described (page 50), from the cell 
of which it is formed, not possessing any stiff thickening layers, 
and thus collapsing when dry, so that it then resembles a more 
or less twisted band with thickened edges (fig. 157, a); while 
liber-cells, such as those forming flax fibres, from having thick 
walls, always maintain their original cylindrical form and taper- 
ing extremities (jig. 157, b). 
On young roots we find also cells prolonged beyond the sur- 
face which are of the nature of hairs, and have therefore been 
termed root-hairs or fibrils (fig. 128) (see Roots). The hairs 
F2 
