COMPOSITION IN SUCCESSIVE STAGES. 219 
Observe that these absolute quantities diminish in the 
stem and leaves after the 1st or 3d period in all cases, and 
increase very rapidly in the ear. 
Arendt found that sulphuric acid existed to a much 
greater degree in the leaves than in the stem, throughout 
the entire growth of the. oat plant, and that after blos- 
soming the lower stem no longer contained sulphur in the 
form of sulphuric acid at all, though its total in the plant 
considerably increased. It is almost certain, then, that 
sulphuric acid originates, either partially or wholly, by 
oxidation of sulphur or some sulphurized compound, in 
the upper organs of the oat. 
Magnesia is translated from the lower stem into the 
upper organs, and in the fruit, especially, it constantly in- 
creases in quantity. 
There is no evidence that lime moves upward in the 
plant. On the contrary, Arendt’s analyses go to show 
that in the ear during the last period of growth, it dimin- 
ishes in quantity, being, perhaps, replaced by magnesia. 
As to potash, no transfer is fairly indicated except from 
the ears. These contained at blossoming (period ITI) a 
maximum of potash. During their subsequent growth 
the amount of potash diminished, being probably displac- 
ed by magnesia. 
The data furnished by Arendt’s analyses, while they in- 
dicate a transfer of matters in the cases just named and in 
most of them with great certainty, do not and cannot.from 
their nature disprove the fact of other similar changes, and 
cannot fix the'real limits of the movements which they 
point out. 
