TEA MAKING 131 
the chemical theory, ascribing the fermentation changes 
to. direct union of the tannin of the cell-contents 
with the oxygen of the air. In 1900, however, he 
described the presence, in the cell-juices, of an (oxidis- 
ing) enzyme through whose agency the union of the 
tannin and atmospheric oxygen is effected. This 
enzyme theory was later confirmed by Mann, Naaninga, 
and Newton (the last-mentioned giving the name 
“thease to the enzyme), and has since found wide- 
spread acceptance. It occasioned much interest and 
surprise, therefore, when Bernard, in 1911, revived the 
micro-organism theory. As far back as 1891 Kozai had 
attributed the fermentation changes to the action of 
bacteria, but his views had given way in the face of 
Bamber’s work. The special attraction of a micro- 
organism theory is readily understood; there is the 
question of the distinctive qualities of a tea being due to 
specific races of organisms, with all the possibilities of 
inoculating inferior grades of leaf with artificially- 
obtained pure cultures of the organism found associated 
with good tea. Bernard’s organisms are not the bacteria 
of Kozai, but yeasts which he finds invariably present 
on the surface of the living tea leaf. Some very arrest- 
ing observations are made by Bernard, but the case 
would not appear to be yet fully established ; so far as 
the writer is aware, no practical application of the theory, 
‘on a commercial scale, has yet been attempted. 
In the light of the fermentation process, the object 
of rolling the leaf, apart from the production of a satis- 
factory ‘‘ twist,”” becomes clear. We have outside the 
leaf the atmospheric oxygen, and within the leaf-cells 
the oxidisable substance (tannin), together with the 
