698 Wisconsin Academy of Sciences, Arts, and Letters. 
rior of the grain is reached the corrosion is more general, with 
the result that the interior is dissolved out. 
Diastase acts somewhat differently in the grains of wheat 
and barley; in these grains, channels are often formed run¬ 
ning from the periphery to the center. These channels later 
spread along certain of the concentric layers, probably the less 
dense, although this could not be definitely determined. 
Salter, on the other hand, is of the opinion that, because 
young starch grains are stained with difficulty by the ordinary 
stains and fake up the orange of the triple stain, they are dense 
and homogeneous starch masses. For the same reasons, he is 
of the opinion that the peripheral layer of older starch grains 
is the densest layer in the grains. His reasons do not appear 
to be well founded. The orange stain combines readily with 
the material formed in the corrosion of the starch grain and 
also, as found by Timberlake, with the substance formed in the 
manufacture of the cell plate. These are transition substances, 
and it is but natural to suppose that the orange-staining pe¬ 
ripheral layer of the starch grain is a third transition substance. 
There is small doubt that this layer differs in chemical compo¬ 
sition from the violet starch layers, and all the evidence seems 
to indicate that it is not a dense layer, but rather a loose 
layer of transitory nature. 
