CONSTITUENTS OF PLANTS. 101 



grown in fields. (Otto). In all the species of the Cin- 

 chona, kinic acid is found ; but the quantity of qui- 

 nina, cinchonina and liine which they contain is 

 most variable. From the fixed bases in the products 

 of incineration, however, we may estimate pretty 

 accurately the quantity of the peculiar organic 

 bases. A maximum of the first corresponds to a 

 minimum of the latter, as must necessarily be the 

 case if they mutually replace one another according 

 to their equivalents. We know that different kinds 

 of opium contain me conic acid, in combination with 

 very different quantities of narcotina, morphia, eodeia, 

 &c. 3 the quantity of one of these alkaloids diminish- 

 ing on the increase of the others. Thus, the smallest 

 quantity of morphia is accompanied by a maximum 

 of narcotina. Not a trace of meconic acid* can be 

 discovered in many kinds of opium, but there is not 

 on this account an absence of acid, for the meconic 

 is here replaced by sulphuric acid. Here also we 

 have an example of what has been before stated, for 

 in those kinds of opium where both these acids exist, 

 they are always found to bear a certain relative pro- 

 portion to one another. 



But if it be found, as appears to be the case in 

 the juice of poppies, that an organic acid may be 

 replaced by an inorganic, without impeding the 

 growth of a plant, we must admit the probability 



* Robiquet did not obtain a trace of meconate of lime from 300 Ibs. 

 of opium, whilst in other kinds the quantity was very considerable 

 Ann. de Chim. liii. p. 425. 



