170 A TEXT-BOOK OF BOTANY. 



sugar substance formed on the hydrolysis of the glucoside. He 

 has given the non-sugar substances the class name of '' Aglykone," 

 and groups the glucosides accordingly into the following three 

 classes: I. Glucosides without Nitrogen Aglykones. II. Gluco- 

 sides with Nitrogen Aglykones. III. Glucosides with Nitrogen 

 and Sulphur Aglykones. Class I is further subdivided as its 

 members yield aliphatic, aromatic, or other derivatives ; each 

 .of these again is further subdivided into a number of subgroups. 

 Among the aliphatic aglykones are included the glucosides jalapin 

 and convolvulin. The glucosides with aromatic aglykones are 

 subdivided as follows: (A) Those yielding benzol derivatives 

 and include arbutin, salicin, populin, gaultherin, etc. (5) Deriva- 

 tives containing the styrol nucleus include coniferin, daphnin, aes- 

 culin, scopolin, fraxin, naringin, and hesperidin. (C) Derivatives 

 containing anthracene in their constitution, as f rangulin, morindin, 

 and the glucosides of emodin, rhein, etc. (D) Glucosides which 

 are derivatives of flavon include apiin, fustin, quercitrin, rutin, 

 xanthorrhannin. II. The glucosides with Nitrogen Aglykones 

 include a number of cyanogenetic glucosides, of which amygdalin 

 is the representative. III. The glucosides with Nitrogen and 

 Sulphur Aglykones include sinigrin and sinalbin found in the 

 genus Sinapis and other genera of the Cruciferae. (Consult 

 J. J. L. van Rijn, " Die Glykoside"; O. A. Oesterle, " Grundriss 

 der Pharmakochemie.") 



PROPERTIES OF THE GLUCOSIDES. Like the alkaloids, some of 

 the glucosides are highly toxic. Among those that possess a high 

 degree of toxicity may be mentioned convallamarin, digitalin, scil- 

 lain, strophanthin, sapotoxin, etc. They are soluble in water, 

 alcohol, ethyl acetate, and chloroform, and insoluble in ether. The 

 aqueous solutions are neutral or but faintly acid. Glucosides 

 may be separated from solutions of salts of the alkaloids owing 

 to the fact that they are soluble in chloroform and some other 

 of the immiscible solvents, providing the solution is slightly acid. 

 Most of the glucosides form well-developed crystals and may be 

 studied with a petrographical microscope (Fig. 99). There is 

 no special class of reagents, as with the alkaloids, used in their 

 detection ; on the other hand, some of them give strikingly 

 distinct color reactions whereby they may be detected in the 





