THE 



CHEMISTEY OF THE FAKM 



CHAPTEK I. 



PLANT GROWTH. 



The Constituents of Plants. —Water — The combustible elements of vege- 

 table matter — The proportion of ash constituents in various parts of 

 plants — The essential and non-essential elements of the ash — Com- 

 position of a crop of grass. Function of the Leaves. — Assimilation of 

 carbon from the air — Formation of vegetable substance — Plant re- 

 spiration — The transpiration of water. Function of the Roots. — Ab- 

 sorption of ash constituents and nitrogenous matter from the soil — 

 The excretion of useless matter by the plant — The part played by ash 

 constituents. Gennination. — General character of seeds — The con- 

 ditions and processes of their germination. Plant DcvclopTncnt. — 

 Annual plants — the order in -which plant constituents are assimilated 

 — Biennial and perennial plants — the storing up of food for a second 

 season — spring sap rich in sugar. 



The first step towards a knowledge of plant chemistry 

 must be an acquaintance with the materials of which 

 plants are built up. 



The Constituents of Plants. — The most abundant 

 ingredient of a living plant is water. Many succulent 

 vegetables, as turnips and lettuce, contain more than 90 

 per cent, of water. Timber felled in the driest time 

 seldom contains less than 40 per cent, of water. 



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