920 Brenchley . — The Development of the Grain of Barley . 
out the percentage of protein nitrogen is rather lower in barley than in 
wheat. 
Ash and phosphoric acid . In barley the percentage of ash in dry 
matter is distinctly higher than in wheat, except in the case of plot C, 
which is below the normal. The actual quantity of phosphoric acid per 
1,000 grains, however, is approximately the same in both the grains. 
N 
The pTr ratio in wheat exceeds that of the normal barley plots, but 
falls considerably below that of C, the P 2 0 5 -starved plot. 
Dextrose and diastatic power. The percentage of dextrose in the dry 
matter of wheat falls far more slowly than in barley, reaching its lowest limit 
after about 24 days in the former, but in 6-1 5 days in the latter, after which 
a constant of about 2 per cent, is maintained in both cases. Consequent on 
this slower fall there is considerably more dextrose actually present in the 
wheat grain in the early stages than in barley. 
The changes in the diastatic power of the grain, as shown by the amount 
of maltose produced, follow very different courses. Even at its maximum 
the diastatic power of barley is less than half that of wheat, and the greatest 
activity is reached at a considerably later date in barley, while the rise and 
fall are far more sudden. 
The maltose formed by 1,000 grains, again, shows totally different 
curves in the two grains, curves between which no correspondence can 
be made out. In wheat the maltose rises steadily at first, finally remaining 
more or less constant, while in barley a considerable rise is followed by 
a corresponding fall. 
From the above comparison it is clear that the progressive changes in 
wheat and barley run a very parallel course though varying in detail. The 
differences are seen to be chiefly due to the prolonged ripening period 
of barley, during which maturation changes occur which are not evident in 
the wheat, owing to the earlier stage at which the latter is harvested. 
One difference between wheat and barley is very noticeable in these two 
sets of experiments. With wheat the manuring of the plots had very little 
effect upon the analyses of the grain and straw ; the course of events ran 
very parallel, the P 2 0 5 -starved plot giving results similar to those from more 
normal plots. With barley, on the contrary, the effect of P 2 0 5 starvation is 
very marked indeed. For a certain time the analyses from plot C run fairly 
parallel to the others, A and B, but after the seventh or eighth three-day 
period a radical change sets in. Some limiting factor comes into play, pre- 
sumably the limitation of available phosphoric acid, and the plant suffers 
accordingly. The dry weight, nitrogen, and ash contained in the plant show 
a steady falling off from this period, the phosphoric acid alone remaining 
constant. In the grain, however, these four properties remain constant or 
even increase slightly, showing that after immigration from the soil has 
