ATROPINE — BERBERIN 



335 



for when the seedlings were exposed to the light in an atmos- 

 phere destitute of carbon dioxide, the asparagin persisted 

 in the seedlings. For the ready demonstration of asparagin, 

 tubers of Dahlia may be employed. Rather thick sections are 

 cut from a tuber while the ra^or is kept dry and transferred 

 to a few drops of alcohol on a glass slide and covered with a 

 coverglass. On the evaporation of the alcohol crystals of aspara- 

 gin in the form of rhombic plates aire deposited on the coverglass 

 and slide. To determine whether the crystals are asparagin, 

 they are treated with a few drops of an entirely saturated solution 

 of asparagin, which must be of the same temperature as the 

 preparation. If the crystals are asparagin, instead of being 

 dissolved they will increase in size, while other substances than 

 asparagin will dissolve in the saturated asparagin solution 

 just as they would in water. It is characteristic of asparagin 

 that if the crystals are heated to ioo° C, they lose their water of 

 crystallization and appear like bright droplets of oil. At 200° 

 asparagin becomes decomposed and forms frothy brown drop- 

 lets which are no longer soluble in water. 



Atropine, Cj^H^jNOg. — This alkaloid with its isomers, 

 hyoscyamin, pseudohyoscyamin, and hyoscin, occurs widely 

 distributed in the Solanaceae. Sections of roots of Atropa Bella- 

 donna contain atropine and yield a brownish precipitate when 

 treated with potassium iodide-iodine. 



Bassorin. — Gum tragacanth, obtained from certain cells of 

 the pith and medullary rays of several species of Astragalus. 

 Swells strongly in water, but does not go into complete solution. 

 Is not colored either by iodine or chloroiodide of zinc. 



Berberin, C^oHi^NO^-t-eH^o!— This yellow alkaloid oc- 

 curs in the young parenchymatous tissue, and in the older 

 xylem portions of Berberis vulgaris, and in representatives of 

 the most various families. With potassium iodide-iodine it 

 forms a reddish-brown precipitate which, by treatment with 

 alcoholic potassium iodide-iodine, becomes changed into tubu- 

 lar or- hair-like forms having a brownish or iridescent green 

 color. Ammonia and nitric acid impart to berberin a reddish- 



