CELL-CONTENTS AND FORMS OF CELLS 223 



turn (Fam. Rutaceae), and Anacardium gum, obtained from 

 Anacardium occidentale. 



2. Gums consisting of mixtures of arabin and cerasin (cerasic 

 acid). To this group belong the exudations formed on a number 

 of trees of the Rosaceae, as cherry, almond, apricot, and plum. 



3. Gums containing bassorin. Tragacanth is the typical gum 



FIG. 121. Citrus vulgaris. Longitudinal section of a young fresh fruit showing a lysig- 

 enous oil canal or duct. Se, oil; Zs, cell sap; PI, cells in which the walls have been dis- 

 solved; f, thin-walled cells; D, thick-walled cells; K, nucleus; Chr, chromoplasts ; o, crystals 

 of calcium oxalate; e, epidermis. After Meyer. 



of this class. Included in this group are a few other gums which 

 find some commercial use, as cocoa-palm gum, obtained from the 

 bark of the cocoa-nut palm; chagual gum, obtained from Puya 

 coarctata (Fam. Bromeliacese), and Moringa gum, obtained from 

 Moringa pterygosperma (Fam. Moringaceae). 



4. Gums containing mixtures of cerasin and bassorin. The 

 East Indian gum, obtained from Cochlospermum Gossypium 



