158 HOW CKOPS GROW. 



silica, potash, and lime, are the principal ingredients. In 

 the chaff and husk, silica constitutes three-fourths of the 

 ash, while in the grain, phosphoric acid appears as the 

 characteristic ingredient, existing there in connection with 

 a large amount of potash, (32 | ,) and considerable mag- 

 nesia. Chlorine acquires its maximum, (11.7| ,)in the 

 middle stem, but in the kernel is present in small quantity, 

 while sulphuric acid is totally wanting in the lower stem, 

 and most abundant in the upper leaves. 



Again, the unequal distribution of the ingredients of 

 the ash is exhibited in the leaves of the sugar beet, which 

 have been investigated by Bretschneider, (Soff. Jahresbe- 

 rieht, 4, 89.) This experimenter divided the leaves of 6 

 sugar beets into 5 series or circles, proceeding from the 

 outer and older leaves inward. He examined each series 

 separately with the following results : 



I. IT. III. IV. V. 



Potash 18.7 25.9 32.8 37.4 50.3 



Soda 15.2 14.4 15.8 15.0 11.1 



Chloride of Sodium... 5.8 6.4 5.8 G.O 6.5 



Lime... 24.2 19.2 18.2 15.8 4.7 



Magnesia 24.5 22.3 13.0 8.9 6.7 



Oxide of Iron 1.4 0.5 0.6 0.6 0.5 



Phosphoric acid 3.3 4.8 5.8 8.4 12.7 



Sulphuric acid ,5.4 5.6 5.6 5.2 5.9 



Silica 1.5 0.8 2.7 2.1 1.5 



From these data we perceive that in the ash of the 

 leaves of the sugar beet, potash and phosphoric acid reg- 

 ularly and rapidly increase in relation to the other ingre- 

 dients from without inward, while lime and magnesia as 

 rapidly diminish in the same direction. The per cent of 

 the other ingredients, viz., soda, chlorine, oxide of iron, 

 sulphuric acid, and silica, remains nearly invariable 

 throughout. 



Another illustration is furnished by the following anal- 

 yses of the ashes of the various parts of the horse-chestnut 

 tree, made by Wolff, (Ackerbau^ 2. Auf., 134) : 



