690 Wisconsin Acad&my of Sciences, Arts, and Letters. 
crystal in a line perpendicular to its surface and of returning 
streams wliich pass in the opposite direction carrying portions 
of the crystal in solution. 
It seems quite possible to explain the small hemispherical 
depressions which appear in the early stages of solution by 
diastase in the same way, as the result of molecular streams 
between the solid and the solvent. But it is only the figures 
formed at the beginning of the corrosion of the starch grain 
that may thus be accounted for. The later stages in corro¬ 
sion. in which the canals penetrate more deeply into the grain, 
and which in some oases follow concentric lines, are explained 
by the fact that certain layers in the interior of the grain are 
more readily acted upon than others by the diastase solution, 
and in this way the solution follows the easily soluble layer 
as the path of least resistance. In the wheat starch grain, it 
could not be determined which layers of the unstained grain, 
the highly refractive or the slightly refractive, form the solu¬ 
tion paths, as the diastase causes the grain to take a fairly ho¬ 
mogeneous stain. 
THE DEVELOPMENT OF THE STARCH GRAIN. 
Regarding the development of the starch grain, three gener¬ 
al views have been held. The first, that the outside of the 
starch grain is the part first formed, later growth taking place 
toward the center, was proposed by Munter (22, pi 194) in 
1845. He treated the starch grains from the rhizome of 
Gloriosa superba L. with sulphuric acid, and because water ap¬ 
pears to be drawn out from the central layers and a large crack 
is formed in the hilum region, he concluded that the central 
layers are softer and more watery, and therefore younger, than 
the outer layers. A similar conclusion was reached by Walpers 
in 1851 (45, p. 905), in his studies on arrow-root starch. Har- 
tig, in 1855 (14, p. 905), examined the starch of Canna and 
potato and came to a somewhat similar conclusion, that the 
growth is from the outside toward the center. Hageli (24), in 
1858, proposed the theory of growth by intussusception for all 
organic structures including the starch grain. This meant to 
