THE OROUPa OF TISSUES, OR TISSUES TSTEMS 63 



secreting cells which manufacture the gummy or resinous 

 matter and then exude it into the cavity (Fig. 42). The 



Fig. 41.— Intercellular spaces. A, in leaf -stalk of a Water-lily : s, star- 

 shaped cells. B, in stem of a Rush ; the cells here all star-shaped. Both 

 cross-sections. 



Fto. 43.— Transverse sections of young stem of IvyfHedera helix). A, 

 young intercellular gum-canal, surrounded by four cells ; c, cambium : B, 

 fully developed canal, g ; b, bast. Magnified 800 times. 



Turpentine-canals of the pines and spruces are of this nature, 

 the well-known turpentine being secreted by one or more 



