ALLIED AND MISCELLANEOUS PRODUCTS 183 



which typifies this class of compounds and shows its relation to am- 

 monia. Among the natural bases are the so-called " ptomaines," 

 which are decomposition products of proteins (fish, meat, etc.) pro- 

 duced by the fermentations of bacteria. Some of them are very toxic. 



There is no known use for the natural bases. Some investigators 

 consider them as intermediate products in the formation of pro- 

 teins, but this does not seem likely or they would be more widely 

 distributed. It is more reasonable to suppose that they are inter- 

 mediate products of protein metabolism under abnormal cir- 

 cumstances, e. g., insufficient oxygen or lack of carbohydrates. 

 Where stored in quantities, as in certain mushrooms, they may be a 

 source of nitrogen reserve. 



Alkaloids. — These compounds are not widely distributed in 

 plants but are associated with certain families such as the Sol- 

 anacese (nightshades) and Papaveracese (poppies). They are 

 generally colorless, odorless, crystalline solids, which are insoluble 

 in water but easily soluble in the common organic solvents. The 

 salts of some alkaloids such as nicotine and quinine sulphates are, 

 however, also soluble in water. Most of them have a decided bitter 

 taste and possess marked physiological or toxic properties, which 

 make them important in pharmacology and medicine. Unlike 

 the natural bases they are " aromatic" compounds, i.e., the 

 carbon atoms are in a ring and not in an open chain. 



Their origin in the plant is in some dispute. Pictet (1907) 

 believes they come from the condensation of simple nitrogen com- 

 pounds, which have arisen from the breaking down of complex 

 forms such as proteins. Baly (Chap. XIV) has proposed that 

 they come from the nitrogen bases parallel with the construction 

 of proteins and not subsequent to it. 



Among the well-known alkaloids are nicotine (tobacco), atropine 

 (nightshade), cocaine (coca), quinine (cinchona), and morphine 

 (poppy) . The formula for nicotine will serve as an example of the 

 group structure. tj 



C H 2 C CH 2 



/% I I 



HC C C CH 2 



HC CH H N 



\/ I 



N CH 



3 



