166 



HISTOLOGY OF MEDICINAL PLANTS 



Fig. i), and digitalis (Plate 60, Fig. 2), and of the fruit of rhus 

 glabra. 



Multicellular multiseriate stalked glandular hairs occur on 

 the stems and leaves of cannabis indica (Plate 60, Fig. 5). 



In the glandular hair of kamala (Plate 60, Fig. 1) the num- 

 ber of secretion cells is variable and papillate in form, and the 

 cuticle is separated from the secretion cells. 



In the glandular hair of hops the outer wall or cuticle is torn 

 away from the secretion cells, and the cavity thus formed serves 

 as a storage cavity. This distended cuticle of the hops shows 

 the outline of the cells from which it was separated. 



^Jn the glandular hairs of the mints the secreted products 

 (volatile oils) are stored between the secretion cells and the outer 

 detached cuticle. This cuticle is elastic, and it becomes greatly 

 distended as the volatile oil increases in amount. 



In many of the so-called glandular hairs, tobacco, belladonna 

 geranium, etc., the synthetic products are retained in the glandu- 

 lar cells, there being no special cavity for their storage. 



These hairs usually contain an abundance of chlorophyll. 



The division wall of multicellular glandular hairs may be 

 vertical, as in the two-celled hair of digitalis (Plate 60, Fig. 2) ; 

 as in horehound (Plate 97, Fig. 6), and as in peppermint (Plate 

 60, Fig. 3); in this case there are eight cells, and they form a 

 more or less flat plate of cells. 



In other hairs the division wall is horizontal; this produces 

 a chain of superimposed secreting cells, as in some of the gland- 

 ular hairs of belladonna leaf (Plate 61, Fig. 1), etc. 



In other hairs the division walls are both vertical and hori- 

 zontal, as in tobacco (Plate 61, Fig. 4), henbane (Plate 61, Fig. 

 3), belladonna (Plate 61, Fig. 1). 



Other characters to be kept in mind in studying glandular 

 hairs are the following: Color of cell contents; size of the 

 cells, whether uniform or variable; character of wall, whether 

 smooth or rough. 



SECRETION CAVITIES 



Secretion cavities are divided into three groups, according 

 to the nature of the origin of the cavity: first, schizogenous 

 cavities, which originate by a separation of the walls of the 



