Denniston—Growth and Organization of the Starch Grain. 697 
ter. It seems to me natural that the parts of the grain 
which contain the most solid starch substance would he the 
ones which are most deeply colored, and the evidence from Fig¬ 
ures 42 and 43 is very convincing that this is the case. This 
is also evidence that the stains are not simply held mechanical¬ 
ly between the particles of starch but that they enter into com¬ 
bination with the latter. 
In old grains of Ganna it is often impossible to differentiate 
layers at the organic center of the grain, the material in this 
region often appearing as a homogeneous mass. If such grains 
be crushed so that radial cracks extend through the dense pe¬ 
ripheral layers, and if these crushed grains are then stained 
with gentian violet and orange, it will be found that the entire 
interior mass of the grain which does not show stratification 
is also bright orange in color. The staining confirms the ob¬ 
servation that the central region of old grains may have been 
altered characteristically in its nature. In corroded grains, 
this central portion is often stained orange after the peripheral 
layers have been penetrated by corrosion channels; or, where 
corrosion has continued, the central mass may be entirely re¬ 
moved before the peripheral layers show much alteration. 
As noted above, if a potato starch grain is treated with a 
10 per cent potassium hydroxide solution, the region surround¬ 
ing the hilum becomes granular in appearance and is the first 
portion of the grain to swell. The outer starch layers are the 
last to be affected, showing that they are, no doubt, the most 
resistant layers of the grain. 
From these facts, it seems probable that the central portion 
of old starch grains has been so modified that it is different in 
composition from the more peripheral layers. It may be a 
transition substance similar to that produced by the action of 
diastase in corroding the grains, as noted further below. 
Fischer finds that the material from this region can be 
squeezed out as a fluid mass from grains mounted in water. 
As just noted, it was found that where large eccentric grains 
such as those of the Ganna or the potato are subjected to the 
action of diastase, channels are formed passing through the 
outer dense layers more or less distinctly, but when the inte- 
