CELL-CONTENTS AND FORMS OF CELLS. 237 



Behave toward iron salts and some other reagents like tannin. 

 They are found in relatively large amounts in a number of the 

 resins and balsams, and occur in rather widely separated families, 

 as follows : Peru balsam and Tolu balsam obtained from certain 

 members of the Leguminosae, styrax from the Hamamelidaceae, 

 benzoin from the Styracaceae, aloe from the Liliaceae, dragon's 

 blood from the Palmae, and the resins from the Umbelliferae, in- 

 cluding ammoniac, galbanum, asafretida, etc. 



2. Resene Resins. These are mostly colorless, indifferent 

 substances occurring in resins and are not only insoluble in 

 potassium hydroxide but exceedingly resistant to it, and are not 

 capable of acetylization. To this group belong the resinous 

 exudations of the Burseraceae, including myrrh, olibanum, and 

 elemi ; also of the Anacardiacese, including mastic ; and of the 

 Dipterocarpaceae, including gurjun balsam and dammar. 



3. Resinolic Acid Resins. These are oxy-acids containing 

 either or both hydroxyl and carboxyl groups. They form color- 

 less crystals and are either free or combined with alcohol in the 

 form of esters. They have an acid reaction and are soluble in 

 solutions of sodium hydroxide, and with difficulty form com- 

 pounds with acetyl chloride. Acids belonging to this group have 

 been obtained from a number of the resinous exudations of the 

 Coniferae, including sandarac, Canada turpentine, and Strass- 

 burg turpentine. It is also obtained from a number of resins 

 which are in the nature of pathological products, as larch turpen- 

 tine, Jura turpentine, and French turpentine. The abietic acid 

 in colophony and the succinoabietic acid found in the fossil resin 

 known as amber, also belong to this class of acids. Furthermore, 

 resinolic acids are found in the fungus Polyporus officinalis, and 

 in some of the exudations of the Leguminosae, including the oleo- 

 resin known as copaiba and the recent-fossil resin, Zanzibar- 

 copal. 



4. Resinol Resins. Resinols are aromatic alcohols which 

 usually form colorless crystals and occur either free or in the 

 form of esters. The principal constituents of guaiac resin belong 

 to this class, namely, guaiaconresinol (guaiaconic acid), 

 guaiacresinol (guaiacic acid), and guaiacinresinol (guaiacinic 

 acid). Resinols are also found in small quantities in other resins. 



