Nov., 1922] SPONSLER — STRUCTURE OF STARCH GRAIN 
489 
visible. Refinement of the apparatus will very probably bring out lines 
which will suggest a different arrangement of atoms than the cubic as 
assumed up to this point. On the other hand, accepting the evidence as 
it exists now, line la may be the /3 line (X = .533 A.) for the 100 planes, 
just as line i is the a line for those planes. If that assumption is correct, 
then d in the equation, \ = 2d sin d, should be the same for both wave- 
lengths. Actually, line la, using X = .533, gives d as 5.02, while line i, 
using X = .617, gives d as 5.04. The two values for d agree very closely, 
but with the range of error so large, nothing more than mere suggestion 
is safe. 
There is another possible significance to the line la which, if verified, 
may lead deeper into the composition of the layers of atoms. The position 
of this line is very close to the place where the reflection from the iii 
planes would occur if these planes were alternately composed of different 
kinds of atoms — for example, of layers of carbon atoms alternating with 
mixed layers of hydrogen and oxygen. Here, again, more refined apparatus 
is needed. 
Quite another set of speculations is started from another photograph. 
If the starch grain were built up of minute crystals as A. Meyer (3, pp. 
1 16-129) contended, then a mass of crushed grains ought to produce the 
same lines that the whole grains do. In order to demonstrate the truth or 
fallacy of this contention, dry potato starch was ground in a pebble mill 
until samples contained no whole grains. Figure 8 shows the result of 
Fig. 8. Above, potato starch, whole grains; below, crushed grains. 
photographing, at the same time, the reflections from the crushed grains 
and from the whole grains. A check photograph gave the same results. 
Careful study of the films failed to reveal any lines produced by the crushed 
starch. It does not seem probable that the crystalline structure could be 
changed into an amorphous form by mere crushing. To test that assump- 
tion, cane sugar was ground in an agate mortar until the size of the minute 
