122 EXPLOITATION OF PLANTS 
which so much depends. The methods of the expert 
tea taster are well known: full attention is paid to the 
appearance and condition of the leaf, but the critical 
features are the strength (“ body ”’), astringency, colour 
and, above all, the flavour and aroma of a standard in- 
fusion which, by simple methods, he makes for himself. 
However, within recent years, some very interesting 
and suggestive work tends to show that, provided the 
chemist pays attention to the relative proportions of the 
chemical constituents of the tea infusion rather than to © 
their percentage amounts, the views of the analyst and 
of the tea taster have a relationship which is of con- 
siderable scientific interest to the one, and gratifying 
to the commercial instincts of the other. 
The following table, adapted from Kozai (1), gives 
an analysis of the dried green leaf of unmanufactured 
(Japanese) tea— \ 
Crude protein 2. . 1 1 «1 4 6 37.38% 
Crude“ fibre” 2. 2. 2. 2. 6 6 4. 1004 
Total “extract”. 2. 2. . 1... 342 
ASH. ob eel 3, BE Ze A ag ee EO 
AANNIN: <3: og 30.3 eae SE) 
CaFFEINE. . . «6 « « + 33 
EssENTIAL OIL . - . small quantity 
Soluble in hot water. . 1. ww 50°9 
ry 
. 
+ 
There is nothing of especial interest in this leaf 
composition apart from the three constituents to which 
tea leaf owes its market value, viz. the essential oil, the 
“tannin” and the caffeine. The essential oil is prob- 
ably characteristic; ‘‘ tannin” is a widely distributed 
plant constituent ; while, as is well known, the alkaloid 
caffeine is of restricted but very interesting occurrence 
in the vegetable kingdom. Ina single genus this latter 
