212 HOW CKOPS GROW. 
hand, examined all the plants of a given plot, large and 
small, perfect and injured. The differences illustrate what 
has been already insisted on, viz., that the development 
of tke plant is greatly modified by the circumstances of its 
growth, not only in reference to its external figure, but ake 
as regards its chemical composition. 
The relative distribution of nitrogen in the parts of the 
plant at the end of the several periods is exhibited by the 
following table, simple inspection of which shows the fluc- 
tuations, (relative,) in the content of this element. The 
percentages are arranged for each period separately, pro- 
ceeding from the highest to the lowest: 
PERIODS. 
I. II. III. IV. Vi 
Upper leaves. Lower leaves. Upper leaves. Ears. Ears. 
3.74 2.39 2.27 2.85 3.04 
Lower leaves. Upper leaves. Lower leaves. Upper leaves. Upper leaves. 
3.38 2.19 2.18 1.91 1.74 
Lower leaves. Ears Ears. Lower leaves. Upper stem, 
2.15 2.06 1.85 1.62 1.56 
Middle stem. Upper stem. Upper stem. Lower leaves. 
1.52 1.34 1.60 1.43 
Upper stem. Middle stem. Middie stem. Middle stem, 
0.87 0.98 1.20 1.17 
Lower stem. Lower stem. Lower stem. Lower stem. 
0.80 0.88 0.83 0.79 
5, Ash—The agreement of the percentages of ash in the 
entire plant, in corresponding periods of the growth of the 
oat, in the independent examinations of Bretschneider and 
Arendt is remarkably close, as appears from the figures 
below. 
PERIODS. 
iL TT: Oe IV. Vie 
Bretschneider ......8.57 5.96 5.33 5.40 
Avendti cis. sds ass 8.03 5.24 5.44 5.20 5.17 
The diminution at the 2d, increase at the 3d, and sub- 
sequent diminution at the 4th period, are observed to run 
parallel in both cases. 
As regards the several parts of the plant, it was found 
