156 PLANT PRODUCTS 



and thrown up into riggs and furrows. The seeds are sown 

 in nurseries in a shady situation, and in very hot districts 

 it is necessary to protect the seedlings from excessive heat 

 at this stage. Some form of partial sterilization of the soil 

 is often adopted by burning the soil, along with weeds, 

 brushwood or other waste. The seedlings are generally 

 transplanted into furrows, where they may possibly be 

 irrigated, and the position of rigg and furrow subsequently 

 reversed in the process of earthing up. Growth has usually 

 proceeded fairly far in thirty or forty days, when side shoots 

 and small buds are cut off. In the fields twigs and sticks 

 are arranged somewhat like a towel-horse, and the leaves 

 arranged on these for drying purposes. In some cases the 

 leaves are fixed to strings, very much like a washerwoman 

 might hang out stockings to dry. Rapid drying produces 

 a pale leaf, but slow drying produces a dark-coloured leaf. 

 The process of maturing does not consist in merely losing 

 water, but the action of oxidizing enzymes is an important 

 part of the process. The starch and sugar almost entirely 

 disappear, and the albuminoids and the tannin decrease, 

 with an increase in the amounts of amides. These changes 

 are all explained by ordinary oxidizing decomposition. 



Caffeine or Theine. This is the alkaloid of tea and coffee 

 (see Section V., pp. 158, 160). Coffee beans contain about i 

 per cent., and tea leaves from about i to 5 per cent. ; 3^ 

 per cent, is considered an ordinary amount of caffeine 

 in tea leaves. Tea is heated for about an hour with three 

 or four times its weight of boiling water, and after filtration 

 is mixed with a quantity of lime equal to that of the tea 

 originally taken. The mixture is subsequently dried on the 

 water-bath, extracted with boiling chloroform, and the 

 solution subsequently recrystallized by alcohol. Theobro- 

 mine, the alkaloid in cocoa, is closely related to caffeine. 



Strychnine is the chief alkaloid in Nux Vomica. The 

 finely powdered seeds are treated with lime and water, and 

 the mixture extracted with chloroform, benzene, or amyl 

 alcohol. 



