6 MISCELLANEOUS PAPERS. 
From what has been said concerning the production of nicotine 
and its functions in the economy of the plant it might be inferred that 
the amount formed is controlled by external conditions of environ- 
ment and not by heredity, but our experiments along this line with 
several varieties and strains, as well as with hybrids, have shown con- 
clusively that there is a well-defined varietal influence distinct from 
external conditions, such as soil, fertilizers, temperature, moisture, 
and sunlight. As has been stated in a previous publication of this 
Department,’ there is every reason to believe that by systematic 
breeding it is practicable to procure strains of the important types 
of tobacco characterized by a high or a low nicotine content, provided 
the external conditions with reference to soils, fertilizers, and cul- 
tural methods are properly controlled. Extensive experiments with 
this object in view are now well under way. This work includes not 
only a systematic study as regards their nicotine content of large 
numbers of selections from different types, but also experiments in- 
tended to determine the relative influence on the production of nico- 
tine of the various factors which go to make up the environment in 
which the plant grows. To these should be added the effects of top- 
ping and suckering, practices which are now almost universal. 
It has already been stated that the maximum content of nicotine 
in the case of the leaf of the tobacco plant is attained just as the leaf 
reaches maturity. After this period the leaf begins to lose a part of 
its nicotine whether the plant is allowed to remain in the field or is 
harvested. Every tobacco grower is familiar with the sharp, pun- 
gent odor so noticeable in the curing shed and in the fermentation 
room, and this odor is due primarily to the nicotine which is escaping 
from the tobacco. From the time the tobacco is hung in the curing 
shed it continues to lose nicotine throughout the curing, fermentation, 
and aging processes. The writer has found that well fermented sam- 
ples of cigar tobacco are still slowly losing their nicotine after being 
kept.in tightly stoppered bottles for more than two years. The cause 
of this continued loss of nicotine will be discussed later. 
RELATION OF TOTAL NICOTINE CONTENT TO THE QUALITY OF 
TOBACCO. 
Although nicotine is the active principle of tobacco its production 
in large quantities is not desirable. On the contrary, the finest grades 
of tobacco contain only moderate (and even relatively small) amounts 
of this principle. It has long been recognized that the aroma is not 
governed by the amount of nicotine in the leaf, but some investi- 
gators have suggested that this important quality is due to its decom- 
4Bureau of Plant Industry Bulletin No. 102, Part VII. ‘“A New Method for 
the Determination of Nicotine in Tobacco.” 1907. 
141—1 
