58 THE CHEMISTRY OF CATTLE FEEDING 



The exact constitution of many of the vegetable alkaloids 

 is unknown. They are usually classified according to their 

 origin as follows : 



1. Opium bases. 



2. Cinchona bases. 



3. Strychnos bases. 



4. Other alkaloids. 



Opium is the dried juice of the green seeds of the poppy 

 plant (papaver somniferum). It is a complex mixture of 

 gummy and resinous matters with which are associated some 

 1 8 or 20 different alkaloids. The latter are present in the 

 form of salts, chiefly of sulphuric and meconic acids- 

 Morphine, Ci7H 19 O 3 N, and narcotine, C22H 23 O7N, are con- 

 sidered the most important in this group. 



Cinchonine, C 19 H22ON 2 , quinine, C 2 oH24O 2 N2, and several 

 others are obtained from the bark of various species of 

 cinchona. 



Strychnine, C 21 H 22 O 2 H 2 , is obtained from Nux Vomica, St. 

 Ignatius bean, False Augustura bark, and other plants. 

 Brucine, C 23 H 26 O 4 N 2 , belongs to the same group. They are 

 all extremely poisonous. 



The following may also be mentioned : atropine, obtained 

 from Atropa Belladonna (night-shade), aconitine, from 

 Aconitum Napellus (monkshood) and solanin from the 

 potato plant. 



The pyridine bases, quinoline bases, and some others are 

 also usually classed with the alkaloids, though they differ 

 markedly both in composition and properties. These sub- 

 stances contain no oxygen, and can be volatilised without 

 decomposition. 



The pyridine bases form a homologous series of the 

 general formula, C,,H 2n _ 5 N. The constitution of the lowest 

 member may be compared with that of benzene 



CH <CH-CH> CH CH <CH-H >N 



'(Benzene.) (Pyridine.) 



The other members of the series picoline (methyl 



