154 H. H. Mann— T/ie Enzymes of the Tea Leaf. [No. 2, 



tinge at apex, sometimes the whole wings have a fuscous tinge ; tegulse 

 black, with a dark red spot in the centre ; nervures black. 



<f. Similar, the whole of the abdomen punctured; the apical 

 segment with eight teeth, two lateral, four apical above, and two below; 

 the abdomen below, except the apical segment, is black, not red. 

 Hab. Deesa. 



Length $ 8-11 mm., cf 7-9 mm. ; Exp. $ 14-18 mm., S 12-14 mm. 



VIII. — Studies in the Chemistry and Physiology of the Tea Leaf. Part J. 

 The Enzymes of the Tea Leaf. — By Harold H. Mann, B.Sc. 

 [ Received November 27fch ; Read December 4th, 1901.] 



The production of a food product from the leaves of plants is in 

 actual practice of very rare occurrence. Except in the case of a few 

 vegetables and potherbs, and of some leaves used only as narcotics and 

 stimulants, it may Jpe said not to exist except in the case of tea. And in 

 the production of tea, if the type of leaf used, the method of collection, 

 the induction by artificial means of a constant unnatural succession of 

 young growmg shoots be taken into consideration, the whole question 

 becomes of so exceptional a character that a study of the chemical and 

 physiological condition prevailing under such circumstances would 

 probably be extremely interesting. If, in addition, such a study be 

 combined with that of the changes which take place in the leaf after 

 plucking until its conversion into black tea, — changes which result in 

 profound alterations in the substances present and which altogether 

 alter the commercial characteristics of these products, the matter becomes 

 one of great economic importance. In the series of papers I hope to 

 contribute to the Asiatic Society on this subject, and of which this is the 

 first, I shall try, however, to very largely eliminate the direct economic 

 interest, which will be reserved for another place and another occasion. 



In order, however, to follow the subject it will be necessary to 

 give a short account of the processes by which tea is produced. The 

 tea leaf as used in this manufacture consists of «the youngest leaf 

 on the plant, and only the youngest two open leaves on each shoot to- 

 gether with the unopened leaf bud are now usually plucked. This 

 necessitates, if a large amount of leaf is not to get too old for plucking, 

 and hence to be wasted, that every bush should be gone over by 

 an expert plucker about every seven days. Having obtained the leaf 

 in this manner, it is allowed to wither— to lose its turgescence— by 

 exposure in very thin layers to air as cool as possible until the whole 

 has got to such a condition that on rubbing in the hand the leaves no 



