1901. J H. H. Mann— TAe Enzymes of the Tea Leaf, 157 



diameter Inside a petri dish, and sterilised. A slight change of colour 

 took place during sterilisation, but afterwards none, and dishes so prepar- 

 ed could be kept for weeks. The sterilised tea leaf thus obtained was 

 then inoculated with fermenting leaf, and in about two days colonies 

 were evidently appearing. After three days' culture, these were examined 

 and inoculated with sterilised tea juice, and after a further three days* 

 growth there, the cultures of the second generation were utilised. In 

 every case only one organism was certainly found. It produced colonies 

 consisting of yellowish brown slimy masses without shape, and raised 

 up like drops from the mass of the sterilised tea leaf. In texture these 

 colonies were sticky and a little ropy. Under the microscope the orga- 

 nism was found to be a small bacillus about V 2 fx long and nearly 1 ft 

 broad. A pure culture having been obtained sterilised leaf was inocul- 

 ated with a solution containing the organism in large amounts. No 

 change whatever took place in colour in three hours, — the normal time 

 of fermentation, — but a sour smell had developed. If freshly rolled 

 leaf, instead of sterilised leaf, were used, the inoculated portion had 

 taken on a sour smell in J J hours, while the check experiment was 

 equally coloured, but the fermentation was proceeding normally. The 

 organism was evidently in fact one of the many lactic acid bacteria and 

 had no part whatever in the normal process of fermentation. Inasmuch 

 as this was the only microbe which could be isolated in this way, as it 

 had no effect on the colouring of the tea leaf, and as it caused the leaf 

 to become sour earlier than it would otherwise have done, one may, I 

 think, take it as finally settled that microbial organisms play no essen- 

 tial part in the fermentation of tea, and that when present they are 

 rather of the nature of impurities than essential factors in the process. 



In the absence of bacteria capable of causing the changes observed 

 during the fermentation of tea, it was natural to look for enzyme action, 

 especially as during the past five years the effect of unorganised 

 ferments has been discovered to be paramount in cases where their 

 influence had hardly been previously suspected. The curing and 

 fermentation of tobacco is an example. Here Oscar Loew* has shown 

 that the changes taking place during both these processes are pri- 

 marily due to the action of enzymes. But in attempting to isolate the 

 active ferments in tea, one is met at the outset by a difficulty pointed 

 out long ago by Brown and Morrisf that it was very difficult to extract 

 enxymes from vegetable tissues in presence of a solution containing 

 tannin. Since the young tea leaf contains twenty per cent, of tannin 



* Reports of the U.S.A. Department Agriculture. Nos. 59, 60 and 6.5, 



1899-1901. 

 f Journal of the Chemical Society. 1893, 



