924 Brenchley . — The Development of the Grain of Barley . 
by a clear hyaline space. Outside all is a kind of bounding layer or ‘ skin 5 , 
which also stains with iodine. 
Two days later, thirteen days after flowering, little advance had 
apparently been made in the infilling of starch, as the sector without 
starch at the embryo level was still very large and extended some dis- 
tance down the grain. The starch itself, however, was far more retentive 
of stain, as the iodine coloration was still evident on the fourth day 
after staining, though the remnants of the pericarp starch had entirely 
lost their colour during the interval. In the thick body of the grain the 
matrix in the cells appeared granular and stained yellow with iodine, 
indicating the protein nature of part of these cell contents. 
By the nineteenth day from flowering the main body of the starch was 
apparently laid down. The starch was thick in the flanks and across 
the bridge, right up towards the tip of the embryo. There was much 
protein in the flanks, staining with iodine, but there seemed to be 
less in the bridge. Along the outer edge of the endosperm, adjacent to 
the embryo, was a band of crushed cells, containing no starch, which 
persisted throughout the development of the grain. These were probably 
endosperm cells which had been depleted of their contents and crushed 
back by the embryo in the course of its growth. 
Though the main skeleton of the starch is laid down in the first 
three weeks from flowering, the entry of starch into the grain is by no 
means completed in this time. The analytical figures show that the cal- 
culated amount of carbohydrate in the grain continues to increase for 
another fortnight or three weeks, practically doubling in quantity, after 
which time it remains fairly constant until the barley is cut. The varia- 
tion in the time of infilling is probably due to weather effects, as bright 
sunny weather tends to hasten the process, bringing the grain to its full 
and mature development more rapidly. The change in colour from green 
to brown is also apparently more closely connected with the weather 
conditions than with the stage of infilling of the starch, as all the plots 
examined began to turn at about the same date, on the accession of 
sunny weather, though the dates of flowering, and in consequence the age 
of the grains, varied as much as ten days. 
Disorganization of Nuclei. While the starch skeleton is being laid 
down, the nuclei are in full activity and are perfect in constitution, show- 
ing their nucleoli clearly. Just about the time that all the endosperm 
cells have received some quota of their starch, changes begin to occur in 
the nuclei, at first in those of the cells in the middle of the flanks at 
the end of the grain away from the embryo. The first indication of 
change is the disappearance of the nucleoli, the nuclei becoming much 
more solid and dense in appearance, staining very darkly with haemato- 
xylin. Very soon they become irregular in shape and eventually develop 
