152 HOW CROPS GROW. 



Ash-ingredients are always present in each cell of every 

 plant. 



The ash-ingredients exist partly in the cell-wall, in- 

 crusted or imbedded in the cellulose, and partly in the 

 plasma or contents of the cell (see p 249). 



One portion of the ash-ingredients is soluble in water, 

 and occurs in the juice or sap. This is true, in general, 

 of the salts of the alkali-metals, and of the sulphates and 

 chlorides of magnesium and calcium. Another portion 

 is insoluble, and exists in the tissues of the plant in the 

 solid form. Silica, the calcium phosphates and the mag- 

 nesium compounds, are mostly insoluble. 



The ash-ingredients may be separated from the volatile 

 matter by burning or by any process of oxidation. In 

 burning, portions of sulphur, chlorine, alkalies, and phos- 

 phorus may be lost, under certain circumstances, by vola- 

 tilization. The ash remains as a skeleton of the plant, 

 and often actually retains and exhibits the microscopic 

 form of the tissues. 



The Proportion of Ash is not Invariable, even ir 

 the same kind of plant, and in the same part of the plant. 

 Different kinds of plants often manifest very marked dif- 

 ferences in the quantity of ash they contain. The fol- 

 lowing table exhibits the amount of ash in 100 parts (of 

 dry matter) of a number of plants and trees, and in theii 

 several parts. In most cases is given an average proportion 

 as deduced from a large number of the most trustworthy 

 examinations. In some instances are cited the extreme 

 proportions hitherto put on record. 



PROPORTIONS OF ASH IX VAHlorS VEGETABLE MATTERS.* 



ENTIRE PLANTS, ROOTS EXCEPTED. 



Avern'.ic. Average. 



Red clover 6.7 



White 



Timothy 7.1 



Potatoes 5.1 



Sugar beet, 16.318.6 17.5 



Field beet, 14.0 21.8 1*.L 



Turnips, 10.719.7 15.5 



Carrot, 15.021.3 17.1 



Hops it.H 



Hemp 4.G 



Flax 4.:! 



H.-alh 4..J 



* These figures are copied unehunired from the old edition, and may 

 differ from later averages, but are approximately correct. 



