66 SETZ.—PRICKLES. —EMERGENCES. 
attached by its base to the surface of the epidermis from whence 
it grows (fig. 154). . 
When the hairs are composed of cells which are short, and 
have their internal walls thickened so that they form stiffened 
processes, they are then called sete or bristles, and the surface is 
termed setose or setaceous. These, slightly modified, form prickles, 
which may be defined as large multicellular hairs springing 
Fie. 152, Fie. 153, Fie. 155; 
ws FOOSE 
ELIAS Lewes 
7 ace y 
Fig. 152. Hairs, each having a spira! fibre in its interior, from the epicarp 
of the fruit of Salria Horminum.—Fig. 153, Scale of the Oleaster 
(Elcagnus).—Fig. 154. Ramenta from the petiole of a Fern. Fig, 155. 
Ramentaceous hair, showing its component cells.—Fig. 156. Prickles 
on a Rose-branch, 
from the epidermis and layer of cells beneath, the walls of 
which are hardened by the deposition of lignin, and which 
terminate in a sharp point (fig. 156). They are especially abun- 
dant on the stems of the Rose and Bramble. Prickles and some 
other allied structures, as warts, &c., which arise from the sub- 
epidermal tissue as well as the epidermis, have been termed Hmer- 
genes. They should be carefully distinguished from spines, to be 
hereafter alluded to when speaking of branches. (See page 107.) 
