RHIZOMES AND ROOTS. 215 



Starch. 



Some rhizomes and roots, as, for instance, gentian, senega 

 and those derived from composite plants, are free, or practically 

 free, from starch; others, such as golden seal, contain but little. 

 It is, however, more usual to find considerable quantities of 

 s-tarch, to the characters of which particular attention must be 

 directed. In the illustrations that accompany this section of 

 t he Atlas, we have endeavoured to retain as accurately as pos- 

 sible the relative size of the various starches, for this often 

 constitutes the most conspicuous difference between them. 



Inulin. 



The rhizomes and roots of composite plants contain this 

 substance as a reserve material in the place of starch. It is 

 generally found in the parenchymatous cells of the bast ring and 

 wood in the form of amorphous or indistinctly crystalline 

 masses. Examined in a mixture of alcohol and glycerin these 

 often exhibit a spheerocrystalline structure ; they dissolve 

 without swelling when heated in water. 



Calcium Oxalate. 



This substance may be entirely absent or it may be present, 

 and then, as usual, in various distinctive forms. Thus bella- 

 donna root contains sandy crystals, gentian root minute 

 needles, orris rhizome very large prisms, rhubarb enormous 

 rosette crystals, ipecacuanha raphides, and so on. In some 

 drugs (orris), these crystals occur in intercellular spaces and 

 n re enclosed in delicate suberised membranes; in others they 

 are contained singly or several together in the interior of 

 certain of the cells. 



