THE STRUCTURE OF THE STARCH GRAIN. 
R. IT. DENNISTON, 
Instructor in Pharmaceutical Botany, University of Wisconsin. 
It has been pointed out by Nageli and others that tlie per¬ 
ipheral part of certain varieties of starch shows a somewhat 
different reaction to stains than the central portions. The 
large eccentric grains from the rhizome of Ganna, for example, 
when treated with the safranin, gentian voilet, orange triple 
stain, show, besides the light and dark violet layers making up 
the body of the grain, an outer layer which is fairly uniform in 
width and which takes the orange stain. 
There are but few data in the literature on the differential 
staining of the various portions of starch grains, but this does 
not seem so remarkable when we consider that the more exact 
methods of fixing and staining technique are of comparatively 
recent introduction. 
In 1847, Yageli (1) published an article on the structure of 
the starch grain in which he held that there is an outer layer of 
the starch grain which is composed of cellulose, or the substance 
of which cell membranes consist. This view was soon dis¬ 
proved, however, by Yon M'ohl (2) who showed that the test 
used by 1ST ageli to distinguish starch from cellulose was unre¬ 
liable. 
Cftiger (3) found a layer between the protoplasm and the 
starch grain, which “did not stain blue with iodine, nor did it 
stain brown so rapidly as the surrounding protoplasm.” As he 
makes no mention of the plastid, this is probably what he saw 
and his figures 1 bear out this view. 
In 1885, Mikosch (4) thought he found evidence of the exist¬ 
ence of an intermediate region, between the grain and the plas¬ 
tid which is filled with what he called a “mother substance for 
the grain.” 
kleyer (5) states that normal starch grains do not possess a 
