8 
RESEARCHES ON THE MANUFACTURE 
and liberal manuring are necessary to obtain a fair crop of the 
leaves from the older plants. 
Still another factor which exerts an influence upon the com¬ 
position of tea-leaves is our peculiar method of screening the 
plants from light for a week or two just before the time of 
picking. By this means, a peculiar fine aroma is said to be 
conferred upon the tea, so that it is very easy, according to 
our tea-drinkers, to tell, beforehand, whether or not the tea 
they drink, originated from screened plants. It is, a priori , 
sure that there should be some difference in the composition 
of the leaves of normally grown plants and those of screened. 
In order to solve the problem experimentally, I selected a small 
plot in a large tea plantation, where a most uniform shooting 
was observed, a part of the plot was covered with wooden 
frames so that the plants within were in complete darkness, 
while the other part was freely exposed to the light. In this 
state the plants were kept for 3 weeks after which time the 
leaves in both parts were picked, when the leaves of the 
screened plants were found to have been completely bleached. 
A partial analysis of these two specimens of leaves gave the 
following figures (per cent of dry matter) : 
Grown in darkness. 
Grown in 
Theine 
. 4-532 
3 - 7 8 4 
Total 
nitrogen.. 
. 7-^35 
6 - 945 
Theine 
>> . 
.I-3 11 
1.0943 
n 
„ per 
cent of 
total 
,, . .. 
.16. 72 
i 5 - 75 
A special trial has shown that there is practically no dif¬ 
ference in the amount of tannin contained in the tea-leaves 
whether etiolated or green. It seems, therefore, that the chief 
difference in the composition of these two specimens of leaves 
lies in the quantities of theine therein contained. This diffe¬ 
rence is, however, not due to any new production of the said 
alkaloid in the darkened plants, but is simply caused by the 
formation of various organic substances, such as fibre, etc. in 
