Breach ley . — The Development of the Grain of Barley. 923 
end a few starch grains occurred in a band of cells stretching across the 
flanks and the side of the bridge next the furrow. The outer mass of cells 
adjacent to the embryo remained quite free, while immediately below the 
level of the embryo the deposition of starch in the flanks was much more 
dense. The starch grains themselves stained an intense dark blue and 
retained the iodine coloration for two days after cutting, indicating a more 
mature stage in development. Proceeding down the grain the dorsal cells 
continued empty of starch for some little distance, the empty cells forming 
a kind of wedge in section, showing perfect nuclei. Gradually the wedge of 
infilled cells became smaller until towards the chalaza starch was evident in 
all cells right up to the aleurone layer on the dorsal side. One feature was 
noticeable in those parts of the grain in which a fair quantity of starch was 
deposited. While the starch grains themselves stained such a deep blue 
colour, it appeared that the matrix in which they were embedded also 
tended to stain, but with a violet colour, at least in the cells in the flanks. 
The violet tint was not noticed in the bridge at this time. Care has to 
be taken to ascertain that this violet colour is not an optical illusion due to 
the thickness of the section — i. e. that the colour is not due to superposed 
starch grains out of focus. Careful examination indicates that this coloured 
matrix is an actual fact. As a possible explanation the idea presents itself 
that the soluble sugars come in from the vascular bundle, passing first 
through the bridge in which the coloured matrix does not seem to occur. 
Passing outwards into the flanks, chemical changes begin to occur, and the 
sugars assimilate more to the nature of starch . 1 While still in this transition 
state it is possible that stages are reached, before the starch grain is actually 
laid down, which are stainable with iodine in KI to some extent, giving the 
violet or purplish matrix. As the perfect starch grains come into being 
they exhibit the characteristic deep blue or black colour with the stain. 
At this stage in the development of the grain the pericarp was beginning to 
suffer from the growth of the enclosed seed. At the top of the grain it was 
still very thick, containing a fair proportion of starch in the deeper seated 
layers and round the vascular bundle. Towards the middle of the grain the 
pericarp was becoming badly crushed on the dorsal side by the pressure of 
the enlarging seed. 
By the eleventh day from flowering the starch was very thickly 
deposited in the flanks right through the grain, though it was still noticeable 
that the grains tended to segregate round the nuclei in the cells. Some 
little way below the level of the embryo the starch did not extend thickly 
right across to the dorsal surface, though all cells showed grains in associa- 
tion with the nuclei. A little nearer the embryo the outer cells were quite 
free from starch grains. High magnification seemed to indicate that each 
starch grain consists of a central core showing evident striation, surrounded 
1 Cf. Maquenne, M. L. : Comptes rendus Acad, des Sciences. Tome cxlvi, 1908, pp. 542-5. 
