MORPHOLOGY OF HIGHER PLANTS. 167 



several other families, being found in the lower orders of plants 

 only in isolated cases. 



It is stored chiefly in the parenchyma cells of the wood and 

 bark of rhizomes, tubers and roots, being also found in the medul- 

 lary-ray cells. It occurs in the form of a colorless, or yellowish, 

 highly refractive, concentrated solution, about 30 per cent, being 

 present in plants during the early fall and spring, when it exists 

 in greatest amount. During winter and also during summer it is 

 changed to levulose. 



According to Dragendorfif there are two forms of inulin ; one 

 of which is amorphous and easily soluble in water, and another 

 which is crystalline and difficultly soluble in water. The latter 

 is probably, however, a modification of the former, and it is not 

 unlikely that the various principles known as pseudoinulin, inu- 

 lenin, helianthenin and synantherin are all modifications of inulin. 



If inulin-containing plants are preserved in alcohol and exam- 

 ined by aid of the microscope, the inulin will be found to have 

 separated in the form of sphere-crystalloids, which are attached 

 to the cell wall (Fig. loi, E; Fig. 105) ; but if the material is 

 first allowed to dry out, the inulin will be found in irregular, 

 almost gum-like lumps, which are with more or less difficulty dis- 

 solved in water. 



Drugs Containing Inulin. — Inulin, in the form of irregular, 

 strongly refractive masses, is found in the following drugs: 

 Inula, lappa, pyrethrum and taraxacum. 



CRYSTALLINE SUBSTANCES. 



The sugars constitute a group of crystalline principles of 

 wide distribution. They occur in the cell-sap, from which by 

 evaporation or on treatment with alcohol they may be crystallized 

 out. Quite a large number of distinct principles belonging to this 

 class have been recognized, of which the following may be men- 

 tioned : 



Dextrose (grape-sugar or dextro-glucose) is found in sweet 

 fruits, the nectaries of the flowers, and stems and leaves of various 

 plants. It crystallizes in needles and varies in amount from i to 2 

 per cent, (in peaches), to 30 per cent', in certain varieties of 



