164 H. H. Mann— r/^c Enzymes of the Tea Leaf. [No. 2, 



There remains to be considered the circumstances which cause the 

 production of the oxidising enzyme by the plant. I have as yet only had 

 the opportinity to touch upon one or two of these. It seemed probable 

 however that the amount of light; received by the plant would very 

 materially influence the amount. Three bushes, side by side, were there- 

 fore taken, and one was so covered up for ten days, so that the leaf grew 

 in darkness not quite suffcient to etiolate the young leaves. Leaf was 

 plucked from all three bushes on the same day, in No. 1 as soon as it 

 was light in the morning, in No. 2 (the darkened plant) soon afterwards, 

 and in No. 3 late in the afternoon. 



From the result it would appear that darkness favours the formation 

 of the oxidase, and that there is a difference in this respect between the 

 leaf gathered in the early morning and that obtained after a day's sun- 

 shine. In the leaf grown entirely in darkness the reserve stock or pro- 

 enzyme seemed to have been increased, but that immediately active was 

 rather lower than in the normally produced leaf. I intend to take up 

 this line of investigation more thoroughly later on. 



In a recent publication I have shown how dependent the quality 

 of tea is on the amount of Phosphoric Acid in the soil. It is curious to 

 find that this connection of flavour and Phosphoric Acid, according to 

 the present experiments, seems to run parallel with the apparent con- 

 nection between Phosphoric Acid in the soil (and also in the leaf,) and 

 the amount of oxidising enzyme. 



I give here the analyses of soil from the gardens A and C above 

 mentioned, and it will be at once seen that the amount of Phosphoric 

 Acid corresponds closely with the amount of enzyme in the leaf, I am 

 disposed to insist on this point in view of the previously indicated re- 

 lationship of quality, i.e., flavour, to Phosphoric Acid in the soil. 



A. C. 



Phosphoric Acid '061 "124 



The only question remaining to be discussed with relation to 

 the oxidase under consideration appears to be its localisation in the 

 leaf and stalk. An attempt was made to determine its position by 

 three methods. The first of these consisted in cutting the sections of 

 leaf and stalk and ascertaining in what cells the brown colour commenced 

 to form. In the leaf this always took place at definite points in 

 the centre of the leaf. In the cells where the browning commenced there 

 seemed to be on examination with a very high power in many cases a 

 small irregular black body from which the browning radiated. This 

 could only be seen where the sections are thin and consisted of little 



