SUCCULENCY OF THE LEAVES. 257 



are disposed to turn black, which is exemplified 

 in the Pekoe kinds of tea ; but the autumnal and 

 old leaves, green, brown, or yellow. The difference 

 in these effects must be ascribed to natural causes, 

 such as the different state of their constituent 

 properties at these two periods of the year. Per- 

 haps spring leaves may be considered to bear the 

 same relation to autumnal, that young leaves do to 

 old. Young leaves, says Liebig, contain more 

 alkalis than old ones ; and old leaves lose their 

 astringency. Again, Peligot states that Pekoe and 

 Gunpowder tea contain a larger proportion of 

 azote than any other tea.* In fact so long as the 

 leaves are engaged in the extension of their own 

 growth, they contain a larger amount, than at any 

 subsequent period, of organizable matter, as starch, 

 sugar, gum, and acids for the formation of their 

 own cellular tissue and woody fibre ; but when they 

 have attained their full maturity, the superabun- 

 dant quantity of this nutriment, above what was 

 necessary for their own formation, is sent off as 

 fast as assimilated for the production of cellular 

 tissue, wood, and new organs in other parts of the 

 tree. The sap is also in a more inspissated state, 

 as has already been observed, in the spring season, 

 than at any subsequent period. Similar effects are 

 also produced by different soils. Some soils will 

 not produce the finest quality of tea. And it is 



* Monographie du The, par J. G. Houssaye, p. 101. 



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