926 Brenchley .—The Development of the Grain of Barley . 
grain show finer networks, similar nuclei are apparent in cells adjacent 
to the embryo while those in the middle of the flanks are coarser, some 
still being only deformed. At the base of the embryo at this date some of 
the cells of the sub-aleuronic layer are beginning to show deformed nuclei, 
and at this level too the flank nuclei are finer. The nuclei under the 
aleurone layer rapidly become more and more involved, and some of those 
round the furrow also show deformation. 
In three or four weeks after the beginning of the nuclear changes most 
of the inner endosperm cells near the embryo are in the network stage, 
though some solid ones remain in evidence just under the aleurone layer and 
in some of the cells round the furrow. 
By the time of harvesting, the majority of the nuclei in the grain are in 
the state of very fine networks, though those in the sub-aleuronic layer and 
round the furrow have not in all cases made so much progress in disorgani- 
zation. But up to the last, the relics of the nuclei are still in evidence, and 
are stainable with Delafield’s haematoxylin, indicating that they do not 
absolutely pass out of existence during the maturation changes. Brown 
and Escombe state that the cells are quite ‘ disintegrated ’ by the time the 
cells are completely matured. If by the term ‘ disintegrated * the total dis- 
appearance of the nuclei is meant, this statement is hardly borne out by 
the later observations, ‘ disorganization ’ expressing the state of affairs more 
accurately. 
A comparison of the senescence of the nuclei in wheat and barley shows 
that in most respects the course of events is very parallel. The phenomena 
of senescence are exactly similar, and in both cases it is the nuclei of the 
cells in the middle of the flanks which first show signs of disorganization, 
while those round the furrow are not affected until comparatively late in 
maturation. One difference is to be noticed — in barley the processes of dis- 
organization appear to advance from both ends of the grain simultaneously, 
the latest region of the grain to be involved being just below the level of the 
embryo; while in wheat the disorganization seems to proceed gradually from 
the tip of the embryo downwards, in exactly the opposite direction to that 
in which the starch is deposited. In barley, as in wheat, the changes are 
evidently caused by pressure, due to the deposition of starch, which crushes 
into the relatively soft nuclei, forcing them out of shape. It is quite possible 
that the difference in the order of progression in the two grains may be due 
to differences in the distribution and amount of pressure exerted, not only by 
the starch grains, but also by the developing embryo. 
Summary. 
1 . The weight of the whole plant increases steadily, until desiccation 
sets in about three weeks before harvest, after which a fall is evident. 
2. The nitrogen, ash, and phosphoric acid increase until a maximum is 
