Denniston—Growth and Organization of the Starch Grain. 673 
of Ganna and potato. Salter’s drawings in a number of cases 
show this peripheral portion of the grain stained bright orange, 
bnt he does not attribute this to a difference in composition 
between this and the inner blue-stained portion. 
I have found a peripheral layer present in some cases and 
not in others, and have further undertaken to determine the 
conditions under which it occurs, as discussed below. The 
method of proving, by the use of Flemming’s triple stain, that 
a differentiated peripheral layer is present in certain grains 
and perhaps at certain stages in the development of all starch 
grains, has been described in detail, but without figures, in a 
previous paper (5). 
The method is in brief as follows: A series of slides was 
prepared by exposing for different lengths of time to the vari¬ 
ous stains. In every case, the slides were exposed to the safra- 
nin for five minutes; after washing in water, six slides were 
exposed to gentian violet for five minutes each, then treated 
with orange for the following different lengths of time: one 
minute, five minutes, ten minutes, twenty minutes, sixty min¬ 
utes and three hours. It was found that with the exposure to 
orange for one minute, the peripheral layer is stained a pale 
violet. The inner layers are stained a dark violet. With the 
exposure to orange for five minutes, a peripheral orange layer 
is plainly differentiated, extending entirely around the violet 
portion of the grain This orange-staining peripheral layer 
appears in all the other preparations in this series. Where 
the exposure to the orange is for sixty or one hundred minutes, 
the layers inside still show a pale violet color. Where the ex¬ 
posure to orange is for three hours, the grain becomes orange 
in color, except for a few layers midway between the hilum 
and the posterior end of the grain which remain violet. 
It is seen from this series of slides that when once the grain 
is stained violet, a long exposure to orange is necessary to re¬ 
move the violet from any of the grain but the layer in question, 
while but a few minutes suffice to remove all traces of violet 
from this layer and to replace iti by orange. This seems to in¬ 
dicate that differences either of a chemical or physical nature 
exist between the body of the starch grain and the outer layer. 
