Nov., 1922] SPONSLER — STRUCTURE OF STARCH GRAIN 
487 
carbon and oxygen atoms was about 18 hours; three different kinds of 
starch were photographed: corn, potato, and cassava. 
The dry powder consisting of whole grains of starch was pressed into 
the specimen-holder just firmly enough to support itself. Potato and cas- 
sava starch were taken at one time ; and corn starch and a blank at another 
time. The exposures were for 18 hours. The voltage was approximately 
40,000, and the current varied between 3 and 5 milliamperes. Figure 7 
shows the results of these exposures. The lines are very much blurred, 
and on that account are difficult to measure. Careful study brought out 
several more lines on the films than are shown in the prints made from them. 
In tables 3, 4, and 5 the measurements and the computed results are 
given. The computations are based on the equation, \ = 2d sin 6, where 
X = .617 A., <i is the distance between planes, and 6 is the glancing angle 
determined from its arc which was measured on the photographic film. 
Table 3. Corn Starch 
No. 
d 
Indices of 
of 
Sin d 
d 
Calculated 
Difference 
Planes of 
Line 
Actual 
from Cube 
Cube 
la 
' -05175 
5.96 A. 
5-87 A. 
-.09 
III(X2) 
I 
.06210 
5-04 
100 
2 
.08020 
3.85 
3-56 
-.29 
no 
3 
.10366 
2.98 
2.91 
-.07 
III 
4 
.11667 
2.64 
2.52 
— .12 
100^2) 
5 
.13399 
2.30 
2.25 
-.05 
210 
6 
.14608 
2.10 
2.06 
-.04 
211 
7 
.15845 
1-95 
1.78 
-•17 
II0(2) 
Table 4. Cassava Starch 
No. 
d 
Indices of 
of 
sin d 
d 
Calculated 
Difference 
Planes of 
Line 
Actual 
from Cube 
Cube 
I 
.06076 
5.08 A. 
... A. 
100 
2 
.08020 
3-85 
3-59 
-.26 
no 
3 
.10366 
2.98 
2.93 
-.05 
III 
4 
.11494 
2.69 
2.54 
-.15 
100(2) 
5 
.13053 
2.36 
2.27 
-.09 
210 
Table 5. Potato Starch 
No. 
d 
Indices of 
of 
Sin e 
d 
Calculated 
Difference 
Planes of 
Line 
Actual 
from Cube 
Cube 
I 
.05902 
5.20 A. 
... A. 
100 
2 
.07962 
3.88 
3-68 
— .20 
no 
3 
.10366 
2.98 
3.00 
+ .02 
III 
4 
.11667 
2.64 
2.60 
-.04 
100(2) 
5 
•I3139 
2.35 
2.32 
-•03 
210 
6 
.14608 
2.10 
2.12 
+ .02 
211 
Before any conclusions are drawn from the tables it must be understood. 
