156 HOW CROPS GROW. 



thence diminished to 16.2. The ash of the bulbs fluc- 

 tuated in the reverse manner, falling from 17. 7 to 8. 7, 

 then rising again to 20.9. 



In general, the proportion of ash of the entire plant 

 diminishes regularly as the plant grows old. 



5. The influence of the soil and season in causing the 

 proportion of ash of the same kind of plant to vary, is 

 shown in the following results, obtained by Wunder 

 Versuchs-Stationen, IV, p. 266) on turnip bulbs, raised 

 during two successive years, in different soils. 



In sandy soil. In loamy soil. 



1st year. 2d year. 1st year. 2d year. 

 Percentofash 13.9 11.3 9.1 10.9 



6. As might be anticipated, different varieties of the 

 same plant, grown on the same soil, take up different 

 quantities of non-volatile matters. 



In five varieties of potatoes, cultivated in the same soil 

 and under the same conditions, Herapath (Qu. Jour. 

 Chem., Soc. II, p. 20) found the percentages of ash in 

 dry matter of the tuber as follows : 



VARIETY OF POTATO. 



White Prince's Axbridge Forty- 

 Apple. Beauty. Kidney. Magpie, fold. 

 Ash per cent... 4.8 3.6 4.3 3.4 3.9 



7. It has been observed further that different individ- 

 uals of the same variety of plant, growing side by side, 

 on the same soil (in the same field, at least), contain dif- 

 ferent proportions of ash-ingredients, according as they 

 are, on the one hand, healthy, vigorous plants, or, on the 

 other, weak and stunted. Pierre (Jaliresbericht uber 

 Agriculturchemie, III, p. 125) found in entire colza 

 plants of various degrees of vigor the following percent- 

 ages of ash in dry matter : 



In extremely feeble plants, 1856 8.0 per cent of ash: 



In very feeble plants, 1857 9.0 " " 



In feeble plants, 1857 11.4 " 



In strong plants, 1857 11.0 



In extre,jnely strong plants, 1857, . , , , , 14.3 " 



