306 BOTANICAL GAZETTE [ocToBER 
starch grains at the ordinary temperature, the grains are colored blue; 
while the solution or filtrate remains colorless or some shade of yellow, 
depending upon the amount or strength of iodine solution that has been 
used. If on the other hand the grains are triturated with sand (one part 
of starch to five of sand) for a short time previous to the addition of the 
water, the filtrate will be colored a deep blue upon the addition of an iodin 
solution. Heretofore it has been supposed by some that the blue colora- 
tion was due to the presence of fine particles which went through the 
filter and were suspended in the filtrate, while in reality there is a true 
solution of the starch; or in other words the soluble starch has been liber- 
ated from the grain by the rupture of the peripheral layer. A polariscopie 
examination of the starch solutions, after clarification by means of talcum, 
showed that they have marked dextro-rotatory properties. The angle of 
rotation for solutions of corn, wheat, maranta, and potato starch ranged 
from 0.3814 to 0.8770°. Furthermore, a microscopic examination of bed 
triturated starch shows the grains to be in various stages of disintegration, 
and this taken together with the behavior of starch toward iodin, as well 
as the other observations referred to, would indicate that the starch grain 
consists of a membrane that is insoluble in water at ordinary temperature, 
and an interior portion which is at least in part soluble in water at ordinary 
temperature, that is consists of soluble starch or starch that is colored 
blue with iodin. This technique enables us to differentiate at once the 
soluble starch present, which heretofore has not been supposed to a 
in the unaltered starch grain. As to whether this substance is identi 
with the granulose of NAGELI (2) is a problem which remains to be deter- 
mined. It may be added that this method furnishes a means of wre 
the constituents in the unaltered grain, and is to be preferred to the me = 
which have been employed heretofore, of using solutions of pare 
mineral acids, which give rise to altered substances, and hence do 
give a true differentiation of the substances as they naturally occut 8 
starch grain. : i 
This brings us then to consider the views of RASPAIL (3), m pee 
with those of others, in regard to the nature of the starch grain, whic 
be summarized as follows: cs tee 
1. The starch grain consists of a membrane which is 1ms0 
water, and a more or less soluble content, as pointed out 
2. It develops from a centric or excentric point, to whic 
layer is added, a view first advanced by FritscHE (4); and 
enlarged upon by ScuimpER (5), who demonstrated that its 
dependent upon the function of the leucoplastids. 
