194 HOW CROPS GROW. 



the leaf-stalks 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 



In young leaves. In full-grown leaves. 



-p - . (dissolved 75.2 37.3 



1 undissolved 24.8 62.7 



, . ( dissolved 69.5 72.4 



- Lime 1 undissolved 30.5 27.6 



-., .. j dissolved 43.6 78.3 



Magnesia j undissolved 5 6.4 21.7 



Phosphoric j dissolved 20.9 19.9 



acid | undissolved 79.1 80.1 



.,. j dissolved 26.8 16.1 



( 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 3 ,) 

 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. 30, Ta- 

 bette.) 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 



