120 HOW CROPS GROW. 



lie^s and in ihe process of putrefaction. It is a violent 

 poison, and is perhaps one of the ingredients which, in 

 the seeds of the vetch and of cotton, prove injurious, or 

 even fatal,' when these seeds are too largely eaten by ani- 

 mals. Oholin and Neurin are syrupy, highly alkaline 

 liquids. 



7. Alkaloids is the general designation that has 

 been applied to the organic bases found in many plants, 

 which are characterized in general by their poisonous 

 and medicinal qualities. CafEein and Theobromin, already 

 noticed, were formerly ranked as alkaloids. We may 

 mention the following : 



Nicotin, CioHi4N2, is the narcotip and intensely poi- 

 sonous principle in tobacco, where it exists in combina- 

 tion with malic and citric acids. In the pure state it is 

 a colorless, oily liquid, having the odor of tobacco in an 

 extreme degree. It is inflammable and-volatile, and so 

 deadly that a single drop will kill' a large dog. French 

 tobacco contains % or 8 per cent ; Virginia, 6 or 7 per 

 cent ; and Maryland and Havana, about 3 per cent of 

 nicotin. Nicotin contains 17.3 per cent of nitrogen, 

 but no oxygen. 



Lupinidin, CsHisN, Lupanin, Ci5H26N'20, and Lu- 

 pinin, G^^i^^Oi, are bases existing in the seeds of the 

 lupin. The first two are liquids ; the last is a crystal- 

 line solid. They are poisonous and are believed to occa- 

 sion the sickness which usually follows the use of lupin- 

 seeds in cattle food. 



Sinapin, CieHasNOs, occurs in white mustard. When 

 boiled with an alkali it is decomposed, yielding neurin 

 as one product. 



Vicin, CasHsiNiiOai, and Convicin, CioHiiNbOt, are 

 crystalline bases that occur in the seeds of the vetch, with 

 regard to whose nature and properties little is known. 



Avenin, O66H21NO18, according to Sanson, is a sub- 

 stance of alkaloidal character, existing in oats. It is said 



