GRAIN OF THE TOBACCO LEAF 
By Charles S. Ridgway, 1 
Assistant , Tobacco and Plant-Nutrition Investigations , Bureau of Plant Industry 
INTRODUCTION 
When the buyer examines a sample of cigar leaf, he takes into account 
such factors as texture, elasticity, color, luster, thickness, and grain. He 
rolls a trial cigar and considers the bum, flavor, aroma, and character 
of the ash. These he judges through long experience and by comparison 
with an arbitrary standard for the crop of that particular year and the 
type of leaf in determining the price he will pay for the tobacco of which 
the sample is representative. Though the character of the grain itself, 
whether it be fine or coarse, close or open, may be a relatively minor 
consideration in fixing the value of a given sample, it is undoubtedly 
closely correlated with some of the other factors considered and is there¬ 
fore of more importance than has hitherto been supposed. 
OCCURRENCE AND GENERAL MACROSCOPIC APPEARANCE OF THE 
GRAIN 
The usual form of the grain of tobacco appears to the unaided eye as 
minute pimples or papillae slightly raised above the general surface of the 
leaf tissue. They are more prominent on the upper surface and vary in 
size from about i mm. in diameter down to bodies so small as to be 
entirely invisible without the aid of the microscope. When a well-cased 
leaf is stretched over the ball of the finger, the grain becomes more con¬ 
spicuous (PI. 15, fig. A and B), and, indeed, it is in this way that the 
tobacco buyer or grader determines the size and distribution of these 
bodies. If a leaf with a coarse grain be pressed between the thumb 
and finger, it feels as though particles of sand were adhering to it. Some 
of the larger grain bodies can be picked out with the point of a knife; 
and when such a grain is pressed between two hard substances, it crushes 
in the same manner as would a particle of crystal, for the grain itself 
is a crystalline body. On burning, these grain bodies swell and cause 
the pearl-like pimples so frequently seen on the ashes of cigars (PI. 15, 
fig. C and D). Grain is a characteristic of cigar tobacco, both domestic 
and imported (7). 2 In the flue-cured types macroscopically visible crys¬ 
talline deposits seem to be entirely absent. However, it is reasonable 
to suppose that all air-cured types possess grain in some degree. 
1 The writer wishes to express his gratitude for helpful suggestions and kind criticisms made by Dr. 
W. W. Gamer, for inorganic and organic analyses made by Mr. C. L. Foubert and Dr. C. W. Bacon, re¬ 
spectively, and for kind cooperation on the part of Mr. Otto Olson in the matter of obtaining material. 
2 Reference is made by number to '‘Literature cited," p. 273. 
Journal of Agricultural Research. 
Dept, of Agriculture, Washington, D. C. 
fu 
(269) 
Vol. vn, No.-4 
Nov. 6, 1916 
G— 99 
