1901.] 



H. H. Mann— T7ie Enzymes of the Tea Leaf. 



i6i 



tion method) induced such profound changes in the tea juice that it was 

 impossible to make the absolute test which this method would have 

 given. When a more rapid colouring of tea juice or tea leaf takes place 

 in presence of an additional quantity of the enzyme, and at the same time 

 proceeds normally, there seems no justification for doubting the essential 

 connection of the oxidase isolated from tea leaf with fermentprocess. 



The next point would naturally be to ascertain the part of the leaf 

 richest in enzyme, and the leaf of the flushing shoot plucked for manu- 

 facture which contained the most. This was therefore determined by 

 carefully separating the leaves from one another and from the stalk, and 

 determining tlie oxidase in each separately by the method previously 

 described. The following results were obtained, the amount present in 

 the tip leaf being unity in each case, and the whole being calculated on 

 the dry matter of the leaf. 



Tip unopened leaf 

 First open leaf 

 Second open leaf 

 Leaf stalk 



Relative amount of active 



Relative total amount of 



enzyme. 



enzyme. 



100 



1-00 



•65 



•61 



■48 



•80(?) 



1-64 



1-39 



This indicates a rapid decrease in the amount of enzyme present 

 as the leaf becomes older, but that the stalk contains a good deal more 

 than any other part of the shoot. The above figures much exaggerate 

 this excess, however, owing to the fact that the stalk contains much more 

 water than the leaf, and as a matter of fact in the fresh condition the 

 tip leaf and the stalk contain about an equal amount of enzyme. It is 

 interesting to compare the relation of various other constituents of the 

 leaves to the enzyme as given above, and for the Acidity, the Tannin, 

 and Phosphoric Acid, we have these as follows : — 





Total 

 A cidity. 



Acidity in the 

 absence of 

 Tannin. 1 



Tannin. 



Phosphoric Acid. 



.Tip leaf 



1-00 



loo 



100 



1-00 



First open leaf 



•94 



1 09 



103 



•88 



Second open leaf 



•94 



1-06 



91 



•75 



Leafstalk.. 



•70 



109 



•86 



•79 



