14 
organic matter is prevented, while consumption still proceeds. With 
the young leaves it is the growth, besides the respiration, that con- 
sumes material and prevents its accumulation. 
In comparing the undiluted juices of overripe and ripe leaves, great — 
differences can at once be noticed by adding a double volume of 
alcohol or phosphotungstie acid, the ripe leaves yieiding a much more 
copious precipitate than the overripe ones. The juice of ripe leaves is, 
further, more slimy and more acid. From the central part of the leaves 
100 sq. cin. were cut out of each side of the midrib and ground with some 
quartz sand and 10 ¢. ¢. of water to a fine pulp in a mortar and directly 
titrated, after the addition of 10 ¢.c. of strong alcohol. The result was 
as follows: 
z Content of 
ee C210 soul free malic 
solution acid in 
for 200 sq. | 100 sq. em. 
|em. of leaf.) of leaf. 
Garam. 
Fupe uppers leas sae ee eee Plies beets oobeds see See 3.8 | 0.012 
Sandor dowerléaki sco. e cec ee Stko esac hi eee sre nee ae ee See ee ee 3.0 | . 010 
| 
From the center of another field, ripe upper leaves and lower or sand 
leaves of the same plant were collected. The lower leaves were of a 
lighter green than the upper ones. The juices were prepared as usual, 
and 10 ¢. ¢. titrated. The juice of the upper leaves required 4.2 ¢. c. of 
one-tenth normal soda solution, while that of the lower leaves required 
but 3.2 c.c. Since it is the sugar principally that gives rise to the | 
formation of acid, we should not be surprised at finding more acid in 
the upper leaves than in the lower, as the production of sugar and 
starch depends upon the access of light to the chlorophyll bodies.! 
Well-ripened leaves, rich in oxidizing enzyms and in nicotine, and 
very rich in soluble matter generally, will yield when normally cured 
the so-called “ gummy ” leaves with a well-developed ‘ grain,” and after 
a thorough sweating a fine aroma, while unripe leaves will show injuries 
after the sweating process and yield, like the sand leaves. and overripe 
leaves, an inferior product. Hence, the single-leaf-curing process would 
be preferable to the method of curing on stalk, since the overripe, ripe, 
and unripe leaves are in the latter method harvested together, to be 
cured under equal conditions. 
It is not the object of this report to give an exhaustive critical com- 
parison of these two methods.” Where labor is very expensive, the 
method of single-leaf curing may be out of the question. The same 
may be said for the priming of the very large leaves of Connecticut 
seed-leaf tobacco. Here in the removal of the lower leaves at their 
‘In organs free of chlorophyll, as the flowers, the direct sunlight can, on the con- 
trary, exert a diminishing effect on the amount of acid. 
* The chemical analysis of fully ripe leaves cured after these two methods does 
not show essential differences. (Behrens. ) 
