176 



PLANT LIFE. 



crystallizarion (fig. 176). The resins, usually dissolved in 

 an oil, are geiiemllv excreted into special intercellular spaces 



Fig. 176. Crystals found in plants. I, calcium carbonate; II-V, calcium oxalate; 

 I [, octahedron with blunt ends ; I II, compound crystals from the nectarj' of a mallow; 

 IV, (I, /', needle crystals fi-aphides) from leaf of fuchsia; V, cell from the fruit-flesh 

 of a rose showing a crystal, k. embedded in an outgrowth of the cell-wall, c . All highly 

 magnified. — After Behrens. 



(fig. 177). Volatile oils are secreted by glandular hairs 



(c, fig. 113); or are formed 

 in the epidermis itself, as in 

 flowers ; or are produced in 

 chambers near the surface, 

 the cells which ])rodiice the 

 oil being disorganized to 

 form the cavit)- in which 



cellular receptacle for gum-i-esin from the tile tlrO] )S lie (llg. I7S). 



fruit of fennel. The secretion has been 



dissolved out by alcohol. Tlie shaded cells r)lhcr materials, SUCh aS 



lining the tube are the secretory tissue. 



Moderately magnified. —After Tschirch. saltSOl liuiC, arCSOUietimeS 



excreted upon the surface of the jilant. I'Vom glands in 

 the flower, nectar, which is a solution of sugar, is excreted 

 (figs. 179, 180), The loss of this fi)od is compensatetl for 

 by its attractiveness for insects, which incitlentally serve for 

 the transfer of pollen from one llower to another. Caout- 



