164 THE PLANT BASES [ch. 



group which includes papaverine, laudanosine, narceine, narcotine 

 and others, and (2) the morphine group including morphine, apomor- 

 phine, codeine, thebaine and others. 



Opium is the dried latex obtained by making incisions in the cap- 

 sules of the Opium Poppy {Papaver somuifenim). 



Allied to the papaverine group is hydrastine which occurs in the 

 root of Hydrastis canadensis (Ranunculaceae). 



The constitution of all these alkaloids is very complex. 



Expt.\bl. Tests for morphine. 



(a) Add a little ferric chloride solution to a solution of a morphiue salt. A deep 

 blue coloration is formed. 



(5) Dissolve some morphine in concentrated sulphuric acid and then after 

 standing about 15hrs. add concentrated nitric acid. A deep blue- violet colour is 

 produced which afterwards changes to red. 



Berberine occurs in the root of the Barberry {Berheris vulgaris) and 

 is also found in isolated genera in Anonaceae, Menispermaceae, Papa- 

 veraceae, Ranunculaceae and Rutaceae. 



Corydaline occurs in Cori/dalis cava (Fumariaceae). 



Many other alkaloid substances have been isolated from a large 

 number of different plants, but since the constitution of most of them 

 is unknown, they have not been classified. 



Purine Bases. 



These substances, as indicated, have a heterocyclic ring structure 

 and are derivatives of purine : the atoms of the ring are numbered in 

 the order indicated below : 

 N=CH 



HC C— NH I I 



Purine itself is a crystalline basic compound (m. p. 211-212° C.) 

 which forms salts with acids. It is composed of two rings, the pyrimi- 

 dine and the iminazole: the latter grouping also occurs in histidine 

 (see p. 121). 



