194 HOW CROPS GROW. 
the leafstalks less, and the stems least. He obtained, 
among others, the following results. (Vs. St., IV, p. 59.) 
Of 100 parts of the following fixed ingredients of clover, 
were dissolved in the sap, and not dissolved— 
dissolved ssxaavans 
undissolved » 24.8 62.7 
dissolved ... 2 
Potash 
Lime | undissolved. . 30. ; 21.6 
‘ iSsOlVEd . 23.2 eee 5 : 
Magnesia | undissolved....... 56.4 QL7 
Phosphoric { dissolved ......... 20.9 19.9 
acid undissolved Lire kaw 79.1 ot 
oe issolved ......... 26.8 16. 
Silica { undissolved....... 73.2 83.9 
These researches demonstrate that potash and soda— 
bodies, all of whose commonly occurring compounds, sili- 
cates excepted, are readily soluble in water—enter into 
insoluble combinations in the plant ; while phosphoric acid, 
which forms insoluble salts with lime, magnesia, and iron, 
is freely soluble in connexion with these bases in the sap. 
It should be added that sulphates may be absent from 
the plant or some parts of it, although they are found in 
the ashes. Thus Arendt discovered no sulphates in the 
lower joints of the stem of oats after blossom, though in 
the upper leaves, at the same period, sulphuric acid, (S O,,) 
formed nearly 7°|, of the sum of the fixed ingredients. 
(Wachsthum der Haferpf., p. 157.) Ulbricht found that 
sulphates were totally absent from the lower leaves and 
stems of red clover, at a time when they were present 
in the upper leaves and blossom. (Vs. St., IV, p. 80, Za- 
belle.) Both Arendt and Ulbricht observed that sulphur 
existed in all parts of the plants they experimented upon; 
in the parts just specified, it was, however, no longer com- 
bined to oxygen, but had, doubtless, become an integral 
part of some albuminoid or other complex organic body. 
Thus the oat stem, at the period above cited, contained a 
quantity of sulphur, which, had it been converted into 
sulphuric acid, would have amounted to 14°|, of the fixed 
