THE VEQETABLE BASES 155 



H H H H 



A A 4 i 



/\ /\ /\ /\ 



HC C CH HC C CH 



HC C CH HC C N 



Y Y Y Y 



! I I 



H H H 



Quinoline, CsH 8 N Isoquinoline, 



The common alkaloids are distributed in the several groups 

 as follows: 



Pyrridine piperidine group; piperine, coniine, nicotine. 

 Pyrrolidine group; hygrine and stachydrine. 

 Tropane group; atropine, hyoscine, cocaine, lupinine. 

 Quinoline group; quinine, cinchonine, strychnine, brucine. 

 Isoquinoline group; papaverine, hydrastine, morphine, codeine, 

 berberine. 



The composition and properties of the individual alkaloids 

 have been extensively studied, because of then* medicinal uses. 

 As they have no known metabolic use to the plants which elaborate 

 them, it will not be worth while to consider all of these investiga- 

 tions hi detail here. The following facts with reference to certain 

 typical members of each group will serve to illustrate the general 

 constitution and properties of the alkaloids. 



Piperine, CiyHigOs, is found in black peppers. Its constitu- 

 tion is represented by the following formula, the group which is 

 united to the piperidine ring, in this case, being piperic acid: 



H 2 



H 2 C CH 2 



>CH 2 

 CH=CH-CH=CH- 



