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. 
