154 HOW CROPS GROW. 



dissected, we shall find that its outer parts are richest in 

 ash. Norton found 



In the husked kernels of brown oats 2.1 per cent of ash. 



In the husk of brown oats 8.2 " " 



In the chaff of brown oats 19.1 " " 



Norton also found that the top of the oat-leaf gave 

 16.22 per cent of ash, while the bottom yielded but 13.66 

 percent. (Am. Jour. Science, Vol. Ill, 1847.) 



From the table it is seen that wood (0.3 to 2.7 per 

 cent) and seeds (1.5 to 3.7 per cent) lower or inner 

 parts of the plant are poorest in ash. The stems of 

 herbaceous plants (3.7 to 7.9 per cent) are next richer, 

 while the leaves of herbaceous plants, which have such 

 an extent of surface, are the richest of all (6 to 8 per 

 cent). 



4. Investigation has demonstrated further that the 

 same plant in different stages of growth varies in the pro- 

 portions of ash in dry matter, yielded both by the entire 

 plant and by the several organs or parts. 



The following results, obtained by Norton, on the oat, 

 illustrate this variation. Norton examined the various 

 parts of the oat-plant at intervals of one week through- 

 out its entire period of growth. He found 



Leaves. Stem. Knots. Chaff. Grain unhusked 



June 4 10.8 10.4 



June 11 10.7 9.8 



June 18 9.0 9.3 



June25 10.9 9.1 



July 2 11.3 7.8 4.9 



July 9 12.2 7.8 4.3 



July 16 12.6 7.9 6.0 3.3 



July 23 16.4 7.9 10.0 9.1 3.6 



July 30 16.4 7.4 9.6 12.2 4.2 



Aug. 6 16.0 7.6 10.4 13.7 4.3 



Aug. 13 20.4 6.6 10.4 18.6 4.0 



Aug. 20 21.1 6.6 11.7 21.0 3.6 



Aug. 27 22.1 7.7 11.2 22.4 3.5 



Sept. 3 20.9 8.3 10.7 27.4 3.6 



Here, in case of the leaves and chaff, we observe a con- 

 stant increase of ash, while in the stem there is a con- 



