46 The Fermentation of Cacao 
preparation of black tea, in which it has been 
positively proved’ that an oxidizing enzyme 
acting on a specific tannin is the real cause of 
the blackening of the leaves. When the oxi- 
dizing enzyme of the tea leaves. is killed by 
steam, the leaves retain their green colour and 
never turn black, thus giving us the green tea 
of commerce.” ; 
Tea leaves contain 7 per cent. tannin and 
over, and the production of a black colour from 
this tannin commences as soon as the leaves 
die, which takes place when they are kept in 
heaps after picking, and are deprived of sun- 
light (death by starvation). Indeed, black tea 
contains less tannin than green tea. In order 
to increase the black colouration, the leaves are 
rolled, which brings their juice to the surface, 
1K. Aso. “Bul. Col. Agr.” Tokyo, Imp. Univ., 4 
(1900-1902), p. 255. It may be of interest to readers to 
remember that, from 1893 to 1897, Dr. Loew occupied’ 
the important position of Professor of Agricultural 
Chemistry at the College of Agriculture, Tokyo Univer- 
sity. See Tropical Life, February, 1910, p. 32,—H.H.S. 
2 Even to-day we are told that whilst great strides 
have been made since the formation of the Scientific 
Department, it is doubtful, according to the Dooars 
correspondent of a contemporary of the Indian Planters’ 
Gazette, if there is any agricultural pursuit about which 
less is known by the ‘men occupied in it .than tea. 
Especially is this the case in the tea house. We succeed 
in turning out quite passable tea, and are at times vain 
enough to think that we have made as good tea as 
it is. possible to produce from the leaf at our disposal. 
But the present methods may be revolutionized at any 
time by new discoveries. Take one branch of manu- 
