STUDIES ON" THE CURING OF LEAF TOBACCO. 15 



the iodin test. Cigar-wrapper-leaf types contain less starch at the 

 time of harvesting than other commercial types of leaf, because the 

 former are harvested at a less mature stage and are produced under 

 conditions less favorable to the accumulation of starch during the 

 ripening period. Muller-Thurgau * has shown that in some cases 

 fully ripe European-grown tobacco leaves may contain upward of 

 40 per cent of starch, and we have found this to be true of some 

 samples of our export types. (Compare pp. 35 and 38). 



One of the most marked physiological differences between the 

 green and cured leaves is the content of protein insoluble in dilute 

 acid. In all cases the protein content of the cured leaves is much 

 less than that of the uncured leaves. 



The content of nitric acid in the green and in the cured leaves is 

 about the same. The green leaves at most contain only traces of 

 ammonia, while the cured leaves contain considerable quantities. 

 The cured leaves contain relatively much larger quantities of amid 

 and amido compounds than the green leaves. The relative content 

 of total nitrogen is somewhat less in the green than in the cured 

 leaves. 



LEAF HARVESTED ON THE STALK. 



The method followed in the preparation of the material and the 

 methods of analysis employed were the same as for the leaves har- 

 vested by priming. The original material was chosen with a view to 

 obtaining samples which would be duplicates, essentially, of those 

 used in the preceding experiments, in order that the stalk-cured 

 leaves might be strictly comparable with those cured after being 

 picked from the stalk. It is, of course, a simple matter to check by 

 analysis the original uniformity of the corresponding lots of the green 

 leaves in each case, since these were detached from the stalks, the 

 leaf web separated from the midribs, and the leaf parts quickly dried. 

 This can not be done so readily, however, with the two lots of cured 

 leaves, because of the fact that when the leaves are cured on the 

 stalk there is a well-defined movement of certain constituents from 

 the leaf into the stalk, causing an additional loss in weight, which can 

 only be determined by direct experiments, as reported in Table I, 

 which require that the green and the cured leaves shall possess the 

 same original weight. 



RESULTS OBTAINED IN THE THREE-YEAR EXPERIMENT. 



The comparative composition of cigar- wrapper leaf cured on the 

 stalk and of the corresponding uncured leaf is shown in section B of 

 Table III. As in the primed leaves, the ash content of the whole leaf 

 is higher in the cured than in the uncured leaves. The cured leaves 



1 Muller, Hermann ( Thurgau). Ueber das Verhalten von Starke und Zucker in reifenden und trock- 

 nenden Tabaksblattern. Landwirstchaftliche Jahrbucher, Bd. 14, p. 485-512, 1885. 



