CONTENTS. 



FilRT I. 



0> THE ORGANIC CONSTITUENTS OF PLANTS. 



LECTURE I. 



IMPORTANCE OP AGRICULTURE. 



.ntroduction p. 11 



Different kinds and states of matter 21 



Carbon, its properties and relations to ve- 

 getable life 23 



Oxygen, its properties and relations to ve- 

 getable life 24 



Hydrogen, its properties and relations to 

 vegetable life p. 25 



Nitrogen, its properties and relations to 

 vegetable life 26 



Rewards of study 27 



LECTURE II. 



CHARACTERISTIC PROPERTIES OP ORGANIC SUBSTANCES. 



On the constitution of the atmosphere 31 



The nature and laws of chemical combi- 

 nation 32 



Of water, and its relations to vegetable life..36 

 Of the co4d produced by the evaporation 

 of water, and its influence on vegetation. .43 



Characteristic properties of organic sub- 



staikces 28 



Relative proportions of organic elements.. 29 

 Of the form or state of combination in 

 which the organic elements enter into 

 and minister to the growth of plants .31 



LECTURE III. 



CARBONIC AND OXALIC ACIDS, THEIR PROPERTIES AND RELATIONS. 



Carbonic acid, its properties and relations 

 to vegetable life 45 



Oxalic acid, its properties and relations to 

 vegetable life 47 



Carbonic oxide, its constitution and pro- 

 perties 48 



Light carburetted hydrogen, the gas of 

 marshes and of coal mines 49 



Ammonia, its properties and relations to 

 vegetable hfe 50 



Nitric acid, its constitution and properties . .56 



Q>iestions to be considered 57 



LECTURE IV. 



SOURCE OP THE ORGANIC ELEMENTS OP PLANTS. 



Form in which the nitrogen enters into 



the circulation of plants 68 



Absorption of ammonia by plants 70 



Absorption of nitric acid by plants 72 



Conclusions 74 



Source of the carbon of plants 58 



Form in which carbon enters into the cir- 

 culation of plants 63 



Source of the hydrogen of plants 64 



Source of the oxygen of plants 66 



Source of the nitrogen of plants .ib. 



LECTURE V. 



HOW DOES THE FOOD ENTER INTO THE CIRCULATION OF PLANTS 1 



General structure of plants, and of their 



several parts 4 75 



The functions of the root 76 



The course of the sap 86 



Functions of the stem SS 



Functions of the leaves 89 



Functions' of the bark 96 



Circumstances by which the functions of 



the various parts of plants are modified . . 97 

 Effects of marling 101 



