Feb. 3 ,1923 Water Content of Barley Kernels During Growth 
339 
diminished as shown by the dry weight, material continued to be added 
for several days. The water content drops more abruptly and somewhat 
in advance of the wet weight, due, of course, to the continued activity 
of starch deposit. 
The actual modifications which occur within the kernel during these 
changes have not been traced definitely. As the bulk of the kernel is 
endosperm tissue, the observable variations are doubtless dependent on 
a phase of endosperm development. The endosperm starts to develop 
about the center of the nucellus. As growth proceeds, new cells are 
added by repeated division of the endosperm cells first laid down. At 
some stage of growth the addition of these new cells is either diminished 
rapidly in the number added per day or, more probably, is interrupted 
Fig. 6.—Average percentage of water in kernels of Baku barley from flowering to maturity at Aberdeen, 
Idaho, in 1919 and 1920. 
entirely except in the region immediately adjacent to the furrow. Later, 
two other developments are possible. As previously pointed out, there 
is a secondary stage of starch formation where small starch kernels 
appear among the large starch kernels of the first starch deposit. It is 
also likely that some of the cells of the starch endosperm are abandoned 
as places of active starch deposit. This certainly occurs in occasional 
cells of the periphery on the dorsal surface most remote from the furrow. 
Cells in the latter region can be observed which by their cell walls indicate 
an age equal to that of adjacent cells but which have very few starch 
grains in their interior. Such cells are, in a way, abnormal, and if there 
is any abandonment that occurs as a phase of maturation, it is of cells 
of normal starch content. In any case it is likely that the stages of 
endosperm development have a direct relation to the changes exhibited 
