March 1, 1903.] 
THE TROPICAL AGRICULTUEIST. 
plaat. It was necessary, however, to isolate the en- 
zyme from the tea leaf, and to obtain it free from 
impurities, or substances with which gum guiacum 
gives the blue reaction. This has been done, and 
the blue colouration obtained when gum guiacum 
and the practically pure enzyme are brought into 
contact. We therefore believe that for our purposes 
the test can be used for the detection of the enzyme in 
'tea leaf, and all our statements are based on observa- 
■'^ions of reaction, with this reagent, 
OCCURRENCE OF ENZYME IN THE TEA PLANT. 
All our experiments show that the enzyme occurs 
most abundantly in the young leaf, but is also pre- 
sent in old leaves and most other parts of the plant. 
It does not occur in definite decreasing proportions as 
one passes from the youngest to the oldest leaf, it 
being often more abundant in the second than the 
first leaf, and occasionally exhibiting a very erratic 
distribution in the active form. In the stem and 
root of the tea plant, the function of the enzyme 
-is probably difierent from that in the leaf ; or it 
may be that more than one enzyme exists in the 
different parts of the plant. Certain it is that the 
reserve bodies in the different parts are quite un- 
like one another, and would require different classes 
of enzymes to render them soluble. 
We have determined the general occurrence of the 
enzyme in teas of all classes from all elevations, 
and it is important to realise that it is apparently i>s 
abundant in low-country teas possessing more flavour 
as in the highest grown teas in Ceylon. It can also 
be stated that there is very little difference in the 
amount present in leaf a few weeks from proniug, 
" and in leaf two or more years from pruning. 
It occurs also in the leaf at all times of the day 
and night, and no great quantitative differences wore 
noticed in leaves plucked at 6 a.m. and 10 p.m. 
Leaves plucked under conditions varyine from severe 
drought to heavy rains showed abundance of the 
enzyme at all times. 
STRUCTURE OF A LEAF, 
Since in the manufacture of tea we are concerned 
almost totally with the parts of the leaf, a brief 
description of them will be here convenient. An 
ordinary flat tea leaf is in reality composed of an ac 
cumulation of microscopic pellets, of a substance 
called protoplnsm. Each of these pellets, or cells, 
has some duties to perform in the life of the plant, 
and here and there "a definite grouping of cells of a 
particular shape and size is seen. The layer of re- 
latively small cells which forms an entire covering 
to the leaf is termed the epidermis ; the layer of long 
' 'brick-shaped cells disposed in rows only along the 
'• upper surface of the leaf constitute=i what is known 
as the palisade tissue, whilst the more or less 
spherical cells composing the lower and middle part 
of the leaf is known as the mesophyll. In the meso- 
phyll are several small bands of conducting cells 
known as the vascular bundles or nerves. 
THE GUM GUIACUM REACTION. 
When a section of a fresth tea leaf is treated with 
enm guiacum a blue colour appears mainly in the 
cells of the epidermis and mesophyll. In many cases 
the epidermis stains before any of the other parts, 
and finally assumes the deepest tint. Sometimes 
the parts around the small vascular bundles iu the 
mesophyll take a deep stain. In every case, yet ex- 
amined, the contents of the palisade cells have re- 
fused to take the blue reaction. This is a very 
important point to notice, as it would appear that 
this portion of the leaf, which is known to play 
the principal part in the manufacture of food mate- 
rials, is characterised with a minimum quantity, if any 
of the active enzyme. 
There seems some hope of yet being able to associate 
the maximum occurrence ot the active enzyme with 
*rhe soluble ferments 
Beynolda Green. 
and fermeotation by J. 
a definite granular texture of the contents of the cell?, 
but the significance of this will be discussed at length 
in a later paper. 
It is worth noting that many of the sections do 
not give the blue reaction until repeated treatment 
with gum guiacum and exposure to air, or only after 
adding another oxidising reagent. This is probably 
due to the enzyme existing in the zymogen or in- 
active state. 
The gum guiacuni must thoroughly mix with the 
cell contents before the blue reaction occurs, and 
only very thin sections will to a certainty give suc- 
cessful results. When very thin sections are used, 
the blue compound is seen to pass away from the 
section, and in consequence of the transient nature 
of the reaction, is likely to be overlooked. 
We have now seen that an enzyme can be generally 
demonstrated in all tea leaves, and have briefly in- 
dicated the manipulation necessary. It will now be 
convenient to discuss the relation between 
ENZYMES AND FLAVOUR. 
In one or two instances the action of an enzyme 
has been utilised commercially to induce chemical 
changes, which result in the production of a more 
or less distinctive flavour. As an instance we may 
tike yeast, a common p ant, from which no less than 
five enzymes have been extracted. It has been found 
that different yeast cells impart to a fluid a different 
olour and flavour, and this has been used on the 
continent in the improvement of certain wines. It 
was shown, that if different portions of the same grape 
juice were fermented with different species ot yeast, 
wines were obtained which differed much in flavour, 
because each species of j east has the power of pro- 
ducing, during fermentation, certain characteristic 
flavouring bodies. As has been previously pointed 
out, however, we must remember that all such fer- 
mentations require a great deal of time for comple- 
tion anil they are therefore not strictly comparable 
with the changes occurring in the manufacture of 
tea. It would be unwise to jump to the conclusion 
that the enzyme in tea is responsible for what we 
at the present time know as flavour, although it ia 
possible, that under certain conditions the enzyme 
will be found to materially affect the quality, and per- 
haps to some extent the flavour. 
It is as well to realise that enzymes of some class 
or other probably exist in every plant, and their 
presence is often in no relation to the production of 
flavouring substances. Even if a flavouring substance 
is produced by the action of an enzyme on some 
store material, it is often a question as to whether 
the change is desirable. These remarks are made on 
account of the fact that many planters seem to 
believe, that if an enzyme is found it is always an 
advantage, and the products of its activity can be 
utilised in manufacture. 
Our experience would point to the conclusion that 
maturity of the leaf, utilised in manufacture, was an 
essential fac tor for the production of a flavoury tea, 
Every planter knows, that as soon as the absolute 
rate of growth is diminished an improvement in 
quality results, even in the low country. This is 
also borne out in a general sense in the marked 
differences iu the quality and flavour of the tea 
grown st high and low elevations, the colder climate 
of the former determining a slower and more stable 
growth. In India we have also the finest flavoured 
teas growing at high elevations, where the climate 
is cold and vegetation grows comparatively slowly. 
Again, we might note that what is koown as an autumn 
flavour is produced in Assam teas as soon as the 
weather gets cold and the bushes more mature from 
pruning. In comparing young leaves from a bush 
four weeks from pruning with young leaves from a 
bush two years, three months after pruning, many 
differences of structure are to be noticed. In the 
leaves from the latter, the wall"" of the cells are 
thicker, they possess a more definite outline, and the 
chlorophyll is more definitely granular, Everything 
