TEA. 205 



the characteristic odor of the drug. The most important 

 microscopical character is found in the epidermal cells. 

 The stomata are small, somewhat immersed, and numer- 

 ous. They lie irregularly over the inferior surface. The 

 epidermis cells are regularly polygonal, and many con- 

 tain spherocrystals as well as irregular rhomboids of cal- 

 cium oxalate. 



Chemistry. — Buchu contains a volatile oil, mucilage, 

 resin, hesperidin, and, perhaps, rutin. The ash is rich 

 in manganese. The volatile oil, 16 per cent., in short 

 buchu, 66 per cent, in the long, consists of a stearopten, 

 diosphenol, having a peppermint odor, and a liquid 

 portion, which by fractionation yields dioscamphor, a 

 substance of a thymol-like odor. The residue yields 

 diosium. 



TEA. 



The leaves of Camellia thea, Link. (Thea Sinensis, 

 Sims.) 



Tea is extensively cultivated throughout tropical 

 countries, but the main source of supply is Asia. The 

 leaf is bifacial, the epidermis of both sides being com- 

 posed of small isodiametric cells. Some are developed 

 into uniceflular trichomes 500 to 700 microns in length. 

 The palisade cells are frequently two-rowed, the lower 

 row being much smaller than the first row. The general 

 mesophyll is open and well provided with intercellular 

 spaces. A number of very characteristic sclereids (stone 

 cells) are present in the mesophyll. These are usually 

 very irregularly contorted and twisted and very thick- 

 walled (lignified). They are commonest in old leaves; 

 in the young leaves being associated with the midrib. 

 The stomata are broadly oval with narrow mouth. 



The characteristic stone cells and hairs of tea are suffi- 

 ciently distinctive. Numerous admixtures with other 

 leaves are used for falsification, but for the most part 

 they may be excluded by reason of the absence of the 



