THE 



CHEMISTEY OF THE FABM. 



CHAPTER 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 

 respiration The transpiration of watef. Function of the Roots. 

 Absorption of ash constituents from the soil The selective power 

 of plants Absorption of nitrogenous matter Cases of union of root 

 with other organisms. Destination of Ash Constituents. The 

 excretion of useless matter by plants The distribution and 

 action of ash constituents in the plant. Germination Gen- 

 eral character of seeds The conditions and processes of their 

 germination. Plant Development. Annual plants The order in 

 which plant constituents are assimilated Exhaustion of roots and 

 stem during formation of seed 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 ivater. 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. 



