Denniston—Growth and Organization of the Starch Grain. 671 
used to plug up holes in the walls of living cells, caused by 
wounds. 
Thus, in a number of cases, we have a transition substance 
either in the formation or solution of carbohydrates, which 
shows a strong affinity for the orange stain. In the case of 
the starch grain and in the cell wall this substance appears to 
he a stage in the formation of still more complex compounds. 
We find the very young starch grains either staining en¬ 
tirely orange or showing a large proportion of orange. We 
find an outer layer of orange material in the older grains, and 
by following the course of development of the starch grain, we 
are led to believe that the orange-staining substance in young 
and old grains is identical. 
ISTewcombe (26, p. 49) has shown that the enzyme which dis¬ 
solves starch in a number of plants is likewise able to dissolve 
cell membranes. As mentioned above, the cell walls of the 
endosperm of a germinating seed of Coix lacryma take a 
bright orange while in process of solution, probably by an en¬ 
zyme action. In these cells the starch grains are also much 
corroded and show orange-stained borders of the corrosive 
channels. 
It is quite possible that the substance first formed from 
starch by the action of diastase is the same that is present in 
the orange layer in the formation of the grain. The evidence 
certainly favors the view that the orange layer is a viscid 
mother substance, similar to that assumed by Mikosch, which 
becomes more and more concentrated by additions from with¬ 
out, until layers of starch form in its interior which first be¬ 
come visible in the dark blue line above referred to. 
In the young grains, starch is deposited equally all round, 
but soon the grain shows an eccentric growth, the mother sub¬ 
stance being formed more abundantly at one end. The plastid, 
however, continues its function of transferring carbohydrate 
material to the mother substance inside, which is too Viscid to 
allow the additions from the thicker part to diffuse readily to 
the mother substance at the opposite end of the grain, under 
the thinner part of the plastid. In this manner, the mother 
substance under the thicker part of the plastid soon becomes 
