232 HISTOLOGY OF MEDICINAL PLANTS 



lion, burdock, elecampane, and pyrethrum contain inulin, but 

 no starch. In saponaria, gentian, and senega neither starch 

 nor inulin occurs. 



When studying roots the nature of the epidermis or the 

 periderm must be considered, as also the number of layers of 

 cortical parenchyma; the occurrence, distribution, and amount 

 of stone cells when present; the presence or absence of the 

 endodermis; the occurrence and structure of bast fibres when 

 present; the nature of the cambium cells; the width and struc- 

 ture of the medullary rays, the size of the wood fibres and wood 

 parenchyma, and the nature of the cell contents and the ar- 

 rangement of the fibro-vascular bundle. 



